A Survey of the Awareness, Offering, and Adoption of OERs and MOOCs in Japan

ERIC Educational Resources Information Center

Shigeta, Katsusuke; Koizumi, Mitsuyo; Sakai, Hiroyuki; Tsuji, Yasuhiro; Inaba, Rieko; Hiraoka, Naoshi

2017-01-01

Awareness about Open Educational Resources (OERs) and the purposes for offering and adopting OERs and Massive Open Online Courses (MOOCs) were analyzed using a detailed survey of higher education across Japan, which was conducted in 2015. A comparison with a similar study conducted in 2013 revealed that awareness of OERs has increased slightly and…

Peer Reviewing of OER in a Contested Domain--An Activity Theoretical Analysis

ERIC Educational Resources Information Center

Algers, Anne; Ljung, Magnus

2015-01-01

Globally, we experience numerous initiatives to increase the adoption of open educational resources (OER), but quality concerns challenge the adoption. In this study we present an analysis of the peer review process of an OER. The OER under review is produced by the European Commission (EU). It has the goal to teach children about farm animal…

An OER Framework, Heuristic and Lens: Tools for Understanding Lecturers' Adoption of OER

ERIC Educational Resources Information Center

Cox, Glenda; Trotter, Henry

2017-01-01

This paper examines three new tools--a framework, an heuristic and a lens--for analysing lecturers' adoption of OER in higher educational settings. Emerging from research conducted at the universities of Cape Town (UCT), Fort Hare (UFH) and South Africa (UNISA) on why lecturers adopt--or do not adopt--OER, these tools enable greater analytical…

Acceptance and Usability of OER in Indian Higher Education: An Investigation Using UTAUT Model

ERIC Educational Resources Information Center

Padhi, Nayantara

2018-01-01

In the global movement towards open knowledge society, open educational resources (OER) have become a prominent contributor as a medium of education, research and training. In India, the phenomenon of OER is still in nascent stage. Although the country has been massively investing on growth and usage of ICT, it still requires acceptance of OER as…

A Preliminary Exploration of the Relationships between Student-Created OER Sustainability, and Students Success

ERIC Educational Resources Information Center

Wiley, David; Webb, Ashley; Weston, Sarah; Tonks, DeLaina

2017-01-01

This article explores the relationship between open educational resources (OER) created by students for use by other students, the long-term sustainability of the movement toward OER, and the success of students who use OER created by other students as part of their core curricular materials. We begin by providing definitions and a broader context…

Opening the Curriculum: Open Educational Resources in U.S. Higher Education, 2014

ERIC Educational Resources Information Center

Allen, I. Elaine; Seaman, Jeff

2014-01-01

Awareness and adoption of open educational resources (OER) has yet to enter the mainstream of higher education. Most faculty remain unaware of OER, and OER is not a driving force for faculty decisions about which educational materials to adopt. This report builds on several previous Babson Survey Research Group efforts exploring the role of OER in…

The Tidewater Z-Degree and the INTRO Model for Sustaining OER Adoption

ERIC Educational Resources Information Center

Wiley, David; Williams, Linda; DeMarte, Daniel; Hilton, John

2016-01-01

A growing body of research confirms the financial and academic benefits that accrue to students whose faculty adopt open educational resources, or OER. While there are no content licensing costs associated with using OER, there are several real costs that must be incurred by an institution that chooses to support its faculty in adopting OER. The…

The use of free online educational resources by Canadian emergency medicine residents and program directors.

PubMed

Purdy, Eve; Thoma, Brent; Bednarczyk, Joseph; Migneault, David; Sherbino, Jonathan

2015-03-01

Introduction Online educational resources (OERs) are increasingly available for emergency medicine (EM) education. This study describes and compares the use of free OERs by the Royal College of Physicians and Surgeons of Canada (RCPSC) EM residents and program directors (PDs) and investigates the relationship between the use of OERs and peer-reviewed literature. A bilingual, online survey was distributed to RCPSC-EM residents and PDs using a modified Dillman method. The chi-square test and Fisher's exact test were used to compare the responses of residents and PDs. The survey was completed by 214/350 (61%) residents and 11/14 (79%) PDs. Free OERs were used by residents most frequently for general EM education (99.5%), procedural skills training (96%), and learning to interpret diagnostic tests (92%). OER modalities used most frequently included wikis (95%), file-sharing websites (95%), e-textbooks (94%), and podcasts (91%). Residents used wikis, podcasts, vodcasts, and file-sharing websites significantly more frequently than PDs. Relative to PDs, residents found entertainment value to be more important for choosing OERs (p<0.01). Some residents (23%) did not feel that literature references were important, whereas all PDs did. Both groups reported that OERs increased the amount of peer-reviewed literature (75% and 60%, respectively) that they read. EM residents make extensive use of OERs and differ from their PDs in the importance that they place on their entertainment value and incorporation of peer-reviewed references. OERs may increase the use of peer-reviewed literature in both groups. Given the prevalence of OER use for core educational goals among RCPSC-EM trainees, future efforts to facilitate critical appraisal and appropriate resource selection are warranted.

Evaluation of Patient Migration Patterns and Related Health Care Costs Within a National Medicare Advantage Prescription Drug Plan After Implementation of an Oxycodone HCl Extended-Release Access Restriction.

PubMed

Chen, Chi-Chang; De, Ajita P; Sweet, Brian; Wade, Rolin L

2017-08-01

Health plans use formulary restrictions (e.g., prior authorization, step therapy, tier change, nonformulary status) in an effort to control cost and promote quality, safety, and appropriate prescription utilization. Some Medicare payers perceive that the inclusion of certain agents, such as branded oxycodone HCl extended-release tablets (OERs), on their formularies is associated with attracting high-cost members to the plan. To evaluate disenrollment rates, patient migration, and subsequent health care costs among OER users who disenrolled from a national Medicare Advantage Prescription Drug plan (study-MAPD) in the plan year following OER nonformulary restriction. A retrospective, longitudinal cohort study using IMS pharmacy and medical claims data between July 1, 2011, and December 31, 2014, was conducted. In the study-MAPD, adults aged ≥ 18 years who were chronic OER users with ≥ 2 OER claims 6 months before the nonformulary restriction date on January 1, 2013 (index date) and with continuous activity in pharmacy and medical claims for 6 months pre- and post-index were included in the study. Comparison years of 2012 and 2014 prerestriction/postrestriction were selected. All groups were followed for 6 months postindex. Year-to-year disenrollment rates of OER patients and the overall plan, as well as patient characteristics and costs of those who disenrolled from and those who remained with the plan, were measured. Costs were compared using a difference-in-differences approach. This study identified 2,935 eligible OER users from the study-MAPD population after imposing nonformulary restrictions on OERs on January 1, 2013. Mean age was 62.1 years, and 59.8% were female. The mean Charlson Comorbidity Index score was 1.83 for those 1,001 patients with medical claims data. For comparison years 2012 (prerestriction) and 2014 (postrestriction), 2,248 and 2,222 OER patients were identified, respectively. Patient characteristics were similar across patient cohorts in all 3 study years. Disenrollment rates for OER users (12.9%, 5.5%, and 14.3% for years 2012, 2013, and 2014, respectively) were lower or similar to those of the overall plan (18.3%, 7.6%, and 14.1%, respectively, for the same 3 years). Approximately 40% of OER users who disenrolled from the study-MAPD migrated to plans also imposing a nonformulary restriction on OERs, while about 25% moved to plans with less restrictive OER coverage. The majority (59.9%) of patients continued OER use irrespective of their disenrollment from the study-MAPD in 2013. Although a nonsignificant decrease ($117; P = 0.340) in per patient per month (PPPM) cost was observed among OER patients postrestriction (from 2012 to 2013), the difference-in-difference analysis indicated a net postrestriction increase of $124 (P = 0.461) in PPPM for OER patients. This study found little evidence to support any consistent directional effect on patient enrollment behavior as a result of an OER non-formulary restriction. Implementation of an OER nonformulary restriction did not lead to higher OER patient disenrollment or lower patient costs in the study-MAPD. Funding for this study was provided by Purdue Pharma. De, Chen, and Wade are employees of QuintilesIMS, a for-profit company that was contracted by Purdue Pharma to undertake this research. Sweet was a paid consultant for Purdue Pharma at the time of this study. Study concept and design were contributed by Chen, Wade, and De. Chen, De, and Wade collected the data, which were interpreted by all the authors. The manuscript was written by Chen and De, along with Sweet and Wade, and revised by all the authors.

What Impacts Do OER Have on Students? Students Share Their Experiences with a Health Psychology OER at New York City College of Technology

ERIC Educational Resources Information Center

Cooney, Cailean

2017-01-01

This article reports findings from a study conducted with students in three sections of a Health Psychology course that replaced a traditional textbook with open educational resources (OER) as the primary course material. The purpose of the study was to learn how OER impacted students. Data were collected in Fall 2015 with students from New York…

Controlling electrodeposited ultrathin amorphous Fe hydroxides film on V-doped nickel sulfide nanowires as efficient electrocatalyst for water oxidation

NASA Astrophysics Data System (ADS)

Shang, Xiao; Yan, Kai-Li; Lu, Shan-Shan; Dong, Bin; Gao, Wen-Kun; Chi, Jing-Qi; Liu, Zi-Zhang; Chai, Yong-Ming; Liu, Chen-Guang

2017-09-01

Developing cost-effective electrocatalysts with both high activity and stability remains challenging for oxygen evolution reaction (OER) in water electrolysis. Herein, based on V-doped nickel sulfide nanowire on nickel foam (NiVS/NF), we further conduct controllable electrodeposition of Fe hydroxides film on NiVS/NF (eFe/NiVS/NF) to further improve OER performance and stability. For comparison, ultrafast chemical deposition of Fe hydroxides on NiVS/NF (uFe/NiVS/NF) is also utilized. V-doping of NiVS/NF may introduce more active sites for OER, and nanowire structure can expose abundant active sites and facilitate mass transport. Both of the two depositions generate amorphous Fe hydroxides film covering on the surface of nanowires and lead to enhanced OER activities. Furthermore, electrodeposition strategy realizes uniform Fe hydroxides film on eFe/NiVS/NF confirmed by superior OER activity of eFe/NiVS/NF than uFe/NiVS/NF with relatively enhanced stability. The OER activity of eFe/NiVS/NF depends on various electrodepositon time, and the optimal time (15 s) is obtained with maximum OER activity. Therefore, the controllable electrodeposition of Fe may provide an efficient and simple strategy to enhance the OER properties of electrocatalysts.

NOAA Office of Exploration and Research > About OER > Program Review >

Science.gov Websites

About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate

Oxygen evolution reaction in nanoconfined carbon nanotubes

NASA Astrophysics Data System (ADS)

Li, Ying; Lu, Xuefeng; Li, Yunfang; Zhang, Xueqing

2018-05-01

Improving oxygen electrochemistry through nanoscopic confinement has recently been highlighted as a promising strategy. In-depth understanding the role of confinement is therefore required. In this study, we simulate the oxygen evolution reaction (OER) on iron oxide nanoclusters under confinement of (7,7) and (8,8) armchair carbon nanotubes (CNTs). The free energies of the four proton coupled electron transfer (PCET) steps and the OER overpotentials are calculated. The Fe4O6 nanocluster confined in (7,7) CNT is found to be the most active for OER among the systems considered in this work. This leads to an increase in catalytic efficiency of OER compared to the hematite (110) surface, which was reported recently as an active surface towards OER. The calculated results show that the OER overpotential depends strongly on the magnetic properties of the iron oxide nanocluster. These findings are helpful for experimental design of efficient catalyst for water splitting applications.

The Organizational Impact of Open Educational Resources

NASA Astrophysics Data System (ADS)

Sclater, Niall

The open educational resource (OER) movement has been growing rapidly since 2001, stimulated by funding from benefactors such as the Hewlett Foundation and UNESCO, and providing educational content freely to institutions and learners across the world. Individuals and organizations are motivated by a variety of drivers to produce OERs, both altruistic and self-interested. There are parallels with the open source movement, where authors and others combine their efforts to provide a product which they and others can use freely and adapt to their own purposes. There are many different ways in which OER initiatives are organized and an infinite range of possibilities for how the OERs themselves are constituted. If institutions are to develop sustainable OER initiatives, they need to build successful change management initiatives, developing models for the production and quality assurance of OERs, licensing them through appropriate mechanisms such as the Creative Commons, and considering how the resources will be discovered and used by learners.

75 FR 15686 - NOAA'S Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-30

...-01] NOAA'S Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015 AGENCY: Office of Ocean Exploration and Research (OER), Oceanic and Atmospheric Research (OAR), National Oceanic... comment. [[Page 15687

An OER Architecture Framework: Needs and Design

ERIC Educational Resources Information Center

Khanna, Pankaj; Basak, P. C.

2013-01-01

This paper describes an open educational resources (OER) architecture framework that would bring significant improvements in a well-structured and systematic way to the educational practices of distance education institutions of India. The OER architecture framework is articulated with six dimensions: pedagogical, technological, managerial,…

Opening education.

PubMed

Smith, Marshall S

2009-01-02

Spurred by the publication of Massachusetts Institute of Technology OpenCourseWare in 2002, the open educational resources (OER) movement, which has rapidly expanded and captured the imagination and energy of millions of creators and users throughout the world, now faces many opportunities and substantial challenges as it moves to become an integral part of the world's educational environment. The confluence of the Web and a spirit of sharing intellectual property have fueled a worldwide movement to make knowledge and education materials open to all for use. OER are content (courses, books, lesson plans, articles, etc.), tools (virtual laboratories, simulations, and games), and software that support learning and educational practice. OER are free on the Web, and most have licenses that allow copyright holders to retain ownership while providing specified rights for use in original and modified forms. At the least, OER have helped to level the distribution of knowledge across the world. A second promise of OER is to help transform educational practices. This article explores the history of and promises and challenges for OER.

NOAA Office of Exploration and Research > Public Affairs > Website & Social

Science.gov Websites

Partners Materials NOAA Initiatives Partnerships Evaluation Public Affairs Overview Website & Social Media News Room OER Symposium Overview Website & Social Media News Room OER Symposium Public Affairs Website & Social Media Home About OER Overview Organization Guiding Documents Organizational Structure

The Challenges of OER to Academic Practice

ERIC Educational Resources Information Center

Browne, Tom; Holding, Richard; Howell, Anna; Rodway-Dyer, Sue

2010-01-01

The degree to which Open Educational Resources (OER) reflect the values of its institutional provider depends on questions of economics and the level of support amongst its academics. For project managers establishing OER repositories, the latter question--how to cultivate, nurture and maintain academic engagement--is critical. Whilst…

Developing a Sustainable Financial Model in Higher Education for Open Educational Resources

ERIC Educational Resources Information Center

Annand, David

2015-01-01

Financial issues regarding the sustainable production, dissemination, and use of Open Educational Resources (OER) in higher education are reviewed and proposed solutions critiqued. Use of OER produce demonstrable cost savings for students. Yet OER development continues to rely almost completely on government and philanthropic funding. This…

Why Not OER?

ERIC Educational Resources Information Center

Doan, Tomalee

2017-01-01

Many observers find it baffling that faculty in higher education have been slow to adopt open educational resources (OER). The William and Flora Hewlett Foundation, a private foundation that makes grants to expand access to learning materials, defines OER as: Teaching, learning, and research resources that reside in the public domain or have been…

Usage Data as Indicators of OER Utility

ERIC Educational Resources Information Center

Mardis, Marcia A.; Ambavarapu, Chandrahasa R.

2017-01-01

A key component of online and blended learning content, open educational resources, (OER) are heralded in a global movement toward high-quality, affordable, accessible, and personalized education. However, stakeholders have expressed concern about scaling OER use due to a lack of means to ensure a fit between learner, resource, and task. Usage…

Politics, Practices, and Possibilities of Open Educational Resources

ERIC Educational Resources Information Center

Phelan, Liam

2012-01-01

In this article, I reflect on the politics, practices and possibilities of the open educational resources (OER). OER raise important implications for current and potential students, for postsecondary education institutions, and for those currently teaching in higher education. The key questions raised by OER centre on the role of teaching in…

Postgraduate Students as OER Capacitators

ERIC Educational Resources Information Center

King, Thomas William

2017-01-01

A comprehensive theoretical, legal and practical basis for OER has been developed over the past fifteen years, supported by the expansion of open source curation platforms and the work of advocacy groups and international bodies. OER's potential has been sufficiently documented; the question remains how best to support, integrate and normalise OER…

Maintaining Momentum toward Graduation: OER and the Course Throughput Rate

ERIC Educational Resources Information Center

Hilton, John, III; Fischer, Lane; Wiley, David; Williams, Linda

2016-01-01

"Open Educational Resources" (OER) have the potential to replace traditional textbooks in higher education. Previous studies indicate that use of OER results in high student and faculty satisfaction, lower costs, and similar or better educational outcomes. In this case study, we compared students using traditional textbooks with those…

Pedagogical Framing of OER--The Case of Language Teaching

ERIC Educational Resources Information Center

Bradley, Linda; Vigmo, Sylvi

2016-01-01

This study investigates what characterises teachers' pedagogical design of OER [Open Educational Resources], and potential affordances and constraints in pedagogical design in an open education practice, when contributing to a Swedish repository Lektion.se. The teachers' framing of the OER shared on the repository included the analyses of a…

The VLAB OER Experience: Modeling Potential-Adopter Student Acceptance

ERIC Educational Resources Information Center

Raman, Raghu; Achuthan, Krishnashree; Nedungadi, Prema; Diwakar, Shyam; Bose, Ranjan

2014-01-01

Virtual Labs (VLAB) is a multi-institutional Open Educational Resources (OER) initiative, exclusively focused on lab experiments for engineering education. This project envisages building a large OER repository, containing over 1650 virtual experiments mapped to the engineering curriculum. The introduction of VLAB is a paradigm shift in an…

U.S. Army Officer Perceptions of the New OER (DA Form 67-8).

DTIC Science & Technology

1982-12-01

SECUNITY CLASSIICATION OF THIS PAGE (Wma 0 a ISeWI I"I --z;-In order to determine the perceptions of Army Officers in the field concerning this OER...perceptions of Army officers in the field concerning this OER, a sample of officers in the grades of 0-3, 0-4, and 0-5 from three Army installations in...involves the examination of the perceptions of U.S. Army officers in the field concerning the present Officer Evaluation Report System (OERS). This will

Understanding Learners' Motivation and Learning Strategies in MOOCs

ERIC Educational Resources Information Center

Alario-Hoyos, Carlos; Estévez-Ayres, Iria; Pérez-Sanagustín, Mar; Delgado Kloos, Carlos; Fernández-Panadero, Carmen

2017-01-01

MOOCs (Massive Open Online Courses) have changed the way in which OER (Open Educational Resources) are bundled by teachers and consumed by learners. MOOCs represent an evolution towards the production and offering of structured quality OER. Many institutions that were initially reluctant to providing OER have, however, joined the MOOC wave.…

A Framework to Integrate Public, Dynamic Metrics into an OER Platform

ERIC Educational Resources Information Center

Cohen, Jaclyn Zetta; Omollo, Kathleen Ludewig; Malicke, Dave

2014-01-01

The usage metrics for open educational resources (OER) are often either hidden behind an authentication system or shared intermittently in static, aggregated format at the repository level. This paper discusses the first year of University of Michigan's project to share its OER usage data dynamically, publicly, to synthesize it across different…

Developing and Deploying OERs in Sub-Saharan Africa: Building on the Present

ERIC Educational Resources Information Center

Wright, Clayton R.; Reju, Sunday A.

2012-01-01

Open educational resources (OERs) have the potential to reduce costs, improve quality, and increase access to educational opportunities. OER development and deployment is one path that could contribute to achieving education for all. This article builds on existing information and communication technology (ICT) implementation plans in Africa and…

Mainstreaming Use of Open Educational Resources (OER) in an African Context

ERIC Educational Resources Information Center

Mays, Tony John

2017-01-01

The study derives from a multi-year project implemented by OER Africa. The project sought to understand how OER might be used as a catalyst for pedagogical transformation in African universities. Within a nondeterminist and interpretivist theoretical framework and an over-arching project methodology of participatory action research, the study made…

Open Educational Resources: Removing Barriers from Within

ERIC Educational Resources Information Center

Mishra, Sanjaya

2017-01-01

Enthusiasts and evangelists of open educational resources (OER) see these resources as a panacea for all of the problems of education. However, despite its promises, their adoption in educational institutions is slow. There are many barriers to the adoption of OER, and many are from within the community of OER advocates. This commentary calls for…

The Impact of OER on Teaching and Learning Practice

ERIC Educational Resources Information Center

Weller, Martin; de los Arcos, Bea; Farrow, Rob; Pitt, Beck; McAndrew, Patrick

2015-01-01

The OER Research Hub has been investigating the impact of OER, using eleven hypotheses, and a mixed methods approach to establish an evidence base. This paper explores the findings relating to teaching and learning. The findings reveal a set of direct impacts, including an increase in factors relating to student performance, increased reflection…

Exploration of Open Educational Resources in Non-English Speaking Communities

ERIC Educational Resources Information Center

Cobo, Cristobal

2013-01-01

Over the last decade, open educational resources (OER) initiatives have created new possibilities for knowledge-sharing practices. This research examines how, where, and when OER are attracting attention in the higher education sector and explores to what extent the OER discussion has moved beyond the English-speaking world. This study analysed…

Visualization Mapping Approaches for Developing and Understanding OER

ERIC Educational Resources Information Center

Connolly, Teresa

2013-01-01

Open educational resources (OER) can be described in numerous ways (Creative Commons, 2012). In this visualization based context, however, OER can be defined as ...teaching, learning and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use or re-purposing by…

NOAA Office of Exploration and Research > About OER > Strategic Plan

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Media News Room OER Symposium Overview Organization Guiding Documents Organizational Structure Map of Strategic Plan Home About OER Overview Organization Guiding Documents Organizational Structure Map of Staff

NOAA Office of Exploration and Research > About OER > Overview

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Media News Room OER Symposium Overview Organization Guiding Documents Organizational Structure Map of Overview Home About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and

NOAA Office of Exploration and Research > About OER > Organization >

Science.gov Websites

Organizational Structure Saturday, May 26, 2018 THIS WEBSITE IS NO LONGER BEING UPDATED OR About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Overview Website & Social Media News Room OER Symposium Guiding Documents Organizational Structure Map

NOAA Office of Exploration and Research > About OER > Contact Us

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Media News Room OER Symposium Overview Organization Guiding Documents Organizational Structure Map of Contact Us Home About OER Overview Organization Guiding Documents Organizational Structure Map of Staff

NOAA Office of Exploration and Research > About OER > Program Review

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Media News Room OER Symposium Overview Organization Guiding Documents Organizational Structure Map of Program Review Home About OER Overview Organization Guiding Documents Organizational Structure Map of

Multimedia Open Educational Resources in Mathematics for High School Students with Learning Disabilities

ERIC Educational Resources Information Center

Park, Sanghoon; McLeod, Kenneth

2018-01-01

Open Educational Resources (OER) can offer educators the necessary flexibility for tailoring educational resources to better fit their educational goals. Although the number of OER repositories is growing fast, few studies have been conducted to empirically test the effectiveness of OER integration in the classroom. Furthermore, very little is…

Equity Considerations for Open Educational Resources in the Glocalization of Education

ERIC Educational Resources Information Center

Willems, Julie; Bossu, Carina

2012-01-01

Open educational resources (OER) have become new buzzwords in the glocalization of education. While OER are often espoused as enabling educational equity, the reality is not always the case. Looking only at the positives of new educational methods can mask perpetuating challenges, which makes the open aspect of OER a misnomer. Taking an…

Institutional Culture and OER Policy: How Structure, Culture, and Agency Mediate OER Policy Potential in South African Universities

ERIC Educational Resources Information Center

Cox, Glenda; Trotter, Henry

2016-01-01

Several scholars and organizations suggest that institutional policy is a key enabling factor for academics to contribute their teaching materials as open educational resources (OER). But given the diversity of institutions comprising the higher education sector--and the administrative and financial challenges facing many institutions in the…

NOAA Office of Exploration and Research > About OER > Organization

Science.gov Websites

the break of the continental shelf between Virginia and New England. May 2011: OER EX Program hosts an Atlantic Basin Workshop to identify exploration targets for the 2012 EX field season. May 2011: OER -U.S. exploration and NOAA Ship Okeanos Explorer's (EX) maiden voyage. Jul 2009: Renewed Joint Project

Open Educational Resources (OER) Usage and Barriers: A Study from Zhejiang University, China

ERIC Educational Resources Information Center

Hu, Ermei; Li, Yan; Li, Jessica; Huang, Wen-Hao

2015-01-01

Open educational resources (OER) as an innovation to share educational resources has been influential in past decade and expected to bring changes to higher education worldwide. There is, however, very limited literature on OER usage, especially from the perspective of college students in developing countries, who are often projected as the…

Questions of Quality in Repositories of Open Educational Resources: A Literature Review

ERIC Educational Resources Information Center

Atenas, Javiera; Havemann, Leo

2014-01-01

Open educational resources (OER) are teaching and learning materials which are freely available and openly licensed. Repositories of OER (ROER) are platforms that host and facilitate access to these resources. ROER should not just be designed to store this content--in keeping with the aims of the OER movement, they should support educators in…

Needs for and Utilization of OER in Distance Education: A Chinese Survey

ERIC Educational Resources Information Center

Chen, Qing; Panda, Santosh

2013-01-01

The recent developments within open educational resources (OERs) and open licensing have generated considerable interest among distance educators since open and distance learning is supposed to be the largest consumer/user of and contributor to OER. In China, given the policy of development and use of elaborate courses, conversion of radio and…

Adoption of Open Educational Resources (OER) Textbook for an Introductory Information Systems Course

ERIC Educational Resources Information Center

Wang, Shouhong; Wang, Hai

2017-01-01

Open educational resources (OER) can make educational resources widely available to all students and educators for free; however, OER are still untried in many academic programmes in higher education. This article reports a case of adoption of an open access textbook for an introductory information systems course and discusses the process and…

Uptake of OER by Staff in Distance Education in South Africa

ERIC Educational Resources Information Center

de Hart, Kerry; Chetty, Yuraisha; Archer, Elizabeth

2015-01-01

Open Educational Resources (OER) emerged within the context of open education which is typically characterized by the sharing of knowledge and resources and the exchange of ideas. Unisa as a mega open distance learning (ODL) university has publicly communicated its intention to take part in the use and creation of OER. As global and local…

OER and the Common Core

ERIC Educational Resources Information Center

Waters, John K.

2013-01-01

If anyone had thought to recognize a K-12 educational buzzword of the year for 2012, it would surely have been "open educational resources" (OER). Ed tech media has fairly hummed with the topic, largely with exciting predictions: OER would give cash-strapped K-12 educators access to high-quality tools and content for their classrooms at little or…

Motives and Tensions in the Release of Open Educational Resources: The UKOER Program

ERIC Educational Resources Information Center

Falconer, Isobel; Littlejohn, Allison; McGill, Lou; Beetham, Helen

2016-01-01

Open educational resources (OER) have been promoted as a path to universal education, supporting economic development and intercultural dialogue. However, to realise these benefits requires greater understanding of the factors that influence both OER supply and use. This paper examines an aspect of the supply side of the OER lifecycle--the motives…

Open Educational Resources: A Faculty Author's Perspective

ERIC Educational Resources Information Center

Illowsky, Barbara

2012-01-01

As the coauthor (with Susan Dean) of a formally for-profit and now open (i.e., free on the web) textbook, "Collaborative Statistics," this author has received many questions about open educational resources (OER), which can be summarized as follows: (1) What are OER?; (2) Why do you support, actively promote, and speak about OER?; (3) If a book is…

The Role of Ru Redox in pH-Dependent Oxygen Evolution on Rutile Ruthenium Dioxide Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoerzinger, Kelsey A.; Rao, Reshma R.; Wang, Xiao Renshaw

Rutile RuO 2 is known to exhibit high catalytic activity for the oxygen evolution reaction (OER) and large pseudocapacitance associated with redox of surface Ru, however the mechanistic link between these properties and the role of pH is yet to be understood. Here we report that the OER activities of the (101), (001) and (111) RuO 2 surfaces were found to increase while the potential of a pseudocapacitive feature just prior to OER shifted to lower potentials (“super-Nernstian” shift) with increasing pH on the reversible hydrogen electrode (RHE) scale. This behavior is in contrast to the (100) and (110) surfacesmore » that have pH-independent Ru redox and OER activity. The link in catalytic and pseudocapacitive behavior illustrates the importance of this redox feature in generating active sites, building new mechanistic understanding of the OER.« less

From OER to OEP: Shifting Practitioner Perspectives and Practices with Innovative Learning Experience Design

ERIC Educational Resources Information Center

Karunanayaka, Shironica P.; Naidu, Som; Rajendra, J. C. N.; Ratnayake, H. U. W.

2015-01-01

Like any other educational resource, the integration of OER in teaching and learning requires careful thought and support for the teaching staff. The Faculty of Education at the Open University of Sri Lanka approached this challenge with the help of a professional development course on OER-based e-Learning. Modules in the course incorporated the…

Using Open Educational Resources in Course Syllabi

ERIC Educational Resources Information Center

Andreatos, Antonios; Katsoulis, Stavros

2012-01-01

The purpose of this article is (1) to review the advantages of using learning objects (LOs) and open educational resources (OER), (2) to propose the enrichment of course syllabi with LOs/OER, (3) to propose new fields to be included in metadata and ways for embedding metadata in LOs/OER, (4) to review the problem of lack of metadata in Web 2.0…

Campus and Online U.S. College Students' Attitudes toward an Open Educational Resource Course Fee: A Pilot Study

ERIC Educational Resources Information Center

Lindshield, Brian L.; Adhikari, Koushik

2013-01-01

Convincing faculty to accept, create, adapt, and adopt open educational resources (OERs) instead of textbooks for their courses has proven challenging because incentives are lacking. One approach to provide incentive to faculty members is an OER course fee, which could be employed in courses that use OERs approved by the institution for courses…

The Open Translation MOOC: Creating Online Communities to Transcend Linguistic Barriers

ERIC Educational Resources Information Center

Beaven, Tita; Comas-Quinn, Anna; Hauck, Mirjam; de los Arcos, Beatriz; Lewis, Timothy

2013-01-01

One of the main barriers to the reuse of Open Educational Resources (OER) is language (OLnet, 2009). OER may be available but in a language that users cannot access, so a preliminary step to reuse is their translation or localization. One of the obvious solutions to the vast effort required to translate OER is to crowd-source the translation, as…

NiFe (Oxy) Hydroxides Derived from NiFe Disulfides as an Efficient Oxygen Evolution Catalyst for Rechargeable Zn-Air Batteries: The Effect of Surface S Residues.

PubMed

Wang, Tanyuan; Nam, Gyutae; Jin, Yue; Wang, Xingyu; Ren, Pengju; Kim, Min Gyu; Liang, Jiashun; Wen, Xiaodong; Jang, Haeseong; Han, Jiantao; Huang, Yunhui; Li, Qing; Cho, Jaephil

2018-05-21

A facile H 2 O 2 oxidation treatment to tune the properties of metal disulfides for oxygen evolution reaction (OER) activity enhancement is introduced. With this method, the degree of oxidation can be readily controlled and the effect of surface S residues in the resulted metal (oxy)hydroxides for the OER is revealed for the first time. The developed NiFe (oxy)hydroxide catalyst with residual S demonstrates an extraordinarily low OER overpotential of 190 mV at the current density of 10 mA cm -2 after coupling with carbon nanotubes, and outstanding performance in Zn-air battery tests. Theoretical calculation suggests that the surface S residues can significantly reduce the adsorption free energy difference between O* and OH* intermediates on the Fe sites, which should account for the high OER activity of NiFe (oxy)hydroxide catalysts. This work provides significant insight regarding the effect of surface heteroatom residues in OER electrocatalysis and offers a new strategy to design high-performance and cost-efficient OER catalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Not All Rubrics Are Equal: A Review of Rubrics for Evaluating the Quality of Open Educational Resources

ERIC Educational Resources Information Center

Yuan, Min; Recker, Mimi

2015-01-01

The rapid growth in Internet technologies has led to a proliferation in the number of Open Educational Resources (OER), making the evaluation of OER quality a pressing need. In response, a number of rubrics have been developed to help guide the evaluation of OER quality; these, however, have had little accompanying evaluation of their utility or…

What's Educational about Open Educational Resources? Different Theoretical Lenses for Conceptualizing Learning with OER

ERIC Educational Resources Information Center

Panke, Stefanie; Seufert, Tina

2013-01-01

In the last decade, the concept of Open Educational Resources (OER) has gained an undeniable momentum. However, it is an easy trap to confuse download and registration rates with actual learning and interest in the adoption and reuse of OER. If we focus solely on access, we cannot differentiate between processes of mere information foraging and…

Making Higher Education More Affordable, One Course Reading at a Time: Academic Libraries as Key Advocates for Open Access Textbooks and Educational Resources

ERIC Educational Resources Information Center

Okamoto, Karen

2013-01-01

Open access textbooks (OATs) and educational resources (OERs) are being lauded as a viable alternative to costly print textbooks. Some academic libraries are joining the OER movement by creating guides to open repositories. Others are promoting OATs and OERs, reviewing them, and even helping to create them. This article analyzes how academic…

OER as Online Edutainment Resources: A Critical Look at Open Content, Branded Content, and How Both Affect the OER Movement

ERIC Educational Resources Information Center

Moe, Rolin

2015-01-01

Despite a rise in awareness and production of open education resources (OER) over the past decade, mainstream media outlets continue to define open in economic terms of consumer cost and not in theoretical terms of remix or appropriation. This period in the "open access" debate has coincided with a proliferation of free-of-charge video…

Who Are the Open Learners? A Comparative Study Profiling Non-Formal Users of Open Educational Resources

ERIC Educational Resources Information Center

Farrow, Robert; de los Arcos, Beatriz; Pitt, Rebecca; Weller, Martin

2015-01-01

Open educational resources (OER) have been identified as having the potential to extend opportunities for learning to non-formal learners. However, little research has been conducted into the impact of OER on non-formal learners. This paper presents the results of a systematic survey of more than 3,000 users of open educational resources (OER).…

Orientation-Dependent Oxygen Evolution on RuO 2 without Lattice Exchange

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoerzinger, Kelsey A.; Diaz-Morales, Oscar; Kolb, Manuel

RuO2 catalysts exhibit record activities towards the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online 3 electrochemical mass spectrometry, which showed no evidence of oxygen exchange on these oriented facets in acidic or basic electrolytes. Similar results were obtained for polyoriented RuO2 films and particles, in contrast to previous work, suggesting lattice oxygen is not exchanged in catalyzing OER onmore » crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by DFT, where more active facets bind oxygen more weakly. This new understanding of the active sites provides a design strategy to enhance the OER activity of RuO2 nanoparticles by facet engineering.« less

Cobalt Covalent Doping in MoS2 to Induce Bifunctionality of Overall Water Splitting.

PubMed

Xiong, Qizhong; Wang, Yun; Liu, Peng-Fei; Zheng, Li-Rong; Wang, Guozhong; Yang, Hua-Gui; Wong, Po-Keung; Zhang, Haimin; Zhao, Huijun

2018-05-28

The layer-structured MoS 2 is a typical hydrogen evolution reaction (HER) electrocatalyst but it possesses poor activity for the oxygen evolution reaction (OER). In this work, a cobalt covalent doping approach capable of inducing HER and OER bifunctionality into MoS 2 for efficient overall water splitting is reported. The results demonstrate that covalently doping cobalt into MoS 2 can lead to dramatically enhanced HER activity while simultaneously inducing remarkable OER activity. The catalyst with optimal cobalt doping density can readily achieve HER and OER onset potentials of -0.02 and 1.45 V (vs reversible hydrogen electrode (RHE)) in 1.0 m KOH. Importantly, it can deliver high current densities of 10, 100, and 200 mA cm -2 at low HER and OER overpotentials of 48, 132, 165 mV and 260, 350, 390 mV, respectively. The reported catalyst activation approach can be adapted for bifunctionalization of other transition metal dichalcogenides. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic surface self-reconstruction is the key of highly active perovskite nano-electrocatalysts for water splitting

NASA Astrophysics Data System (ADS)

Fabbri, Emiliana; Nachtegaal, Maarten; Binninger, Tobias; Cheng, Xi; Kim, Bae-Jung; Durst, Julien; Bozza, Francesco; Graule, Thomas; Schäublin, Robin; Wiles, Luke; Pertoso, Morgan; Danilovic, Nemanja; Ayers, Katherine E.; Schmidt, Thomas J.

2017-09-01

The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts. In this study, by combining a scalable cutting-edge synthesis method with time-resolved X-ray absorption spectroscopy measurements, we were able to capture the dynamic local electronic and geometric structure during realistic operando conditions for highly active OER perovskite nanocatalysts. Ba0.5Sr0.5Co0.8Fe0.2O3-δ as nano-powder displays unique features that allow a dynamic self-reconstruction of the material’s surface during OER, that is, the growth of a self-assembled metal oxy(hydroxide) active layer. Therefore, besides showing outstanding performance at both the laboratory and industrial scale, we provide a fundamental understanding of the operando OER mechanism for highly active perovskite catalysts. This understanding significantly differs from design principles based on ex situ characterization techniques.

In situ investigation on ultrafast oxygen evolution reactions of water splitting in proton exchange membrane electrolyzer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, Jingke; Kang, Zhenye; Yang, Gaoqiang

We present that the oxygen evolution reaction (OER) is a half reaction in electrochemical devices, including low-temperature water electrolysis, which is considered as one of the most promising methods to generate hydrogen/oxygen for the storage of energy. It is affected by many factors, and its mechanism is still not completely understood. A proton exchange membrane electrolyzer cell (PEMEC) with optical access to the surface of anode catalyst layer (CL) coupled with a distinguished high-speed and micro-scale visualization system (HMVS) was developed to in situ investigate OERs. It was revealed in real time that OERs only occur on the anode CLmore » adjacent to liquid/gas diffusion layer (LGDL). The CL electrical conductivity plays a crucial role in OERs on CLs. The large in-plane electrical resistance of CLs becomes a threshold of OERs over the entire CL, and causes a lot of catalyst waste in the middle of LGDL pores. Moreover, the oxygen bubble nucleation, growth, and detachment and the effect of current density on those processes were also characterized. Here, this study proposes a new approach for better understanding the mechanisms of OERs and optimizing the design and fabrication of membrane electrode assemblies.« less

In situ investigation on ultrafast oxygen evolution reactions of water splitting in proton exchange membrane electrolyzer cells

DOE PAGES

Mo, Jingke; Kang, Zhenye; Yang, Gaoqiang; ...

2017-08-25

We present that the oxygen evolution reaction (OER) is a half reaction in electrochemical devices, including low-temperature water electrolysis, which is considered as one of the most promising methods to generate hydrogen/oxygen for the storage of energy. It is affected by many factors, and its mechanism is still not completely understood. A proton exchange membrane electrolyzer cell (PEMEC) with optical access to the surface of anode catalyst layer (CL) coupled with a distinguished high-speed and micro-scale visualization system (HMVS) was developed to in situ investigate OERs. It was revealed in real time that OERs only occur on the anode CLmore » adjacent to liquid/gas diffusion layer (LGDL). The CL electrical conductivity plays a crucial role in OERs on CLs. The large in-plane electrical resistance of CLs becomes a threshold of OERs over the entire CL, and causes a lot of catalyst waste in the middle of LGDL pores. Moreover, the oxygen bubble nucleation, growth, and detachment and the effect of current density on those processes were also characterized. Here, this study proposes a new approach for better understanding the mechanisms of OERs and optimizing the design and fabrication of membrane electrode assemblies.« less

Cobalt-Doped Perovskite-Type Oxide LaMnO3 as Bifunctional Oxygen Catalysts for Hybrid Lithium-Oxygen Batteries.

PubMed

Liu, Xiao; Gong, Hao; Wang, Tao; Guo, Hu; Song, Li; Xia, Wei; Gao, Bin; Jiang, Zhongyi; Feng, Linfei; He, Jianping

2018-03-02

Perovskite-type oxides based on rare-earth metals containing lanthanum manganate are promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte. Perovskite-type LaMnO 3 shows excellent ORR performance, but poor OER activity. To improve the OER performance of LaMnO 3 , the element cobalt is doped into perovskite-type LaMnO 3 through a sol-gel method followed by a calcination process. To assess electrocatalytic activities for the ORR and OER, a series of LaMn 1-x Co x O 3 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) perovskite oxides were synthesized. The results indicate that the amount of doped cobalt has a significant effect on the catalytic performance of LaMn 1-x Co x O 3 . If x=0.3, LaMn 0.7 Co 0.3 O 3 not only shows a tolerable electrocatalytic activity for the ORR, but also exhibits a great improvement (>200 mV) on the catalytic activity for the OER; this indicates that the doping of cobalt is an effective approach to improve the OER performance of LaMnO 3 . Furthermore, the results demonstrate that LaMn 0.7 Co 0.3 O 3 is a promising cost-effective bifunctional catalyst with high performance in the ORR and OER for application in hybrid Li-O 2 batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dramatically Bringing down the Cost of Education with OER: How Open Education Resources Unlock the Door to Free Learning

ERIC Educational Resources Information Center

Wiley, David; Green, Cable; Soares, Louis

2012-01-01

The nation is in the midst of a revolution in education. For the first time in human history, tools to enable everyone to attain all the education they desire are available. And best of all this education is available at almost no cost. The key to this sea of change in learning is open education resources, or OER. OER are educational materials…

Enhanced activity of gold-supported cobalt oxide for the electrochemical evolution of oxygen.

PubMed

Yeo, Boon Siang; Bell, Alexis T

2011-04-13

Scanning electron microscopy, linear sweep voltammetry, chronoamperometry, and in situ surface-enhanced Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) occurring on cobalt oxide films deposited on Au and other metal substrates. All experiments were carried out in 0.1 M KOH. A remarkable finding is that the turnover frequency for the OER exhibited by ∼0.4 ML of cobalt oxide deposited on Au is 40 times higher than that of bulk cobalt oxide. The activity of small amounts of cobalt oxide deposited on Pt, Pd, Cu, and Co decreased monotonically in the order Au > Pt > Pd > Cu > Co, paralleling the decreasing electronegativity of the substrate metal. Another notable finding is that the OER turnover frequency for ∼0.4 ML of cobalt oxide deposited on Au is nearly three times higher than that for bulk Ir. Raman spectroscopy revealed that the as-deposited cobalt oxide is present as Co(3)O(4) but undergoes progressive oxidation to CoO(OH) with increasing anodic potential. The higher OER activity of cobalt oxide deposited on Au is attributed to an increase in fraction of the Co sites present as Co(IV) cations, a state of cobalt believed to be essential for OER to occur. A hypothesis for how Co(IV) cations contribute to OER is proposed and discussed. © 2011 American Chemical Society

Understanding Interactions between Manganese Oxide and Gold That Lead to Enhanced Activity for Electrocatalytic Water Oxidation

PubMed Central

2015-01-01

To develop active nonprecious metal-based electrocatalysts for the oxygen evolution reaction (OER), a limiting reaction in several emerging renewable energy technologies, a deeper understanding of the activity of the first row transition metal oxides is needed. Previous studies of these catalysts have reported conflicting results on the influence of noble metal supports on the OER activity of the transition metal oxides. Our study aims to clarify the interactions between a transition metal oxide catalyst and its metal support in turning over this reaction. To achieve this goal, we examine a catalytic system comprising nanoparticulate Au, a common electrocatalytic support, and nanoparticulate MnOx, a promising OER catalyst. We conclusively demonstrate that adding Au to MnOx significantly enhances OER activity relative to MnOx in the absence of Au, producing an order of magnitude higher turnover frequency (TOF) than the TOF of the best pure MnOx catalysts reported to date. We also provide evidence that it is a local rather than bulk interaction between Au and MnOx that leads to the observed enhancement in the OER activity. Engineering improvements in nonprecious metal-based catalysts by the addition of Au or other noble metals could still represent a scalable catalyst as even trace amounts of Au are shown to lead a significant enhancement in the OER activity of MnOx. PMID:24661269

Generalizable, Electroless, Template-Assisted Synthesis and Electrocatalytic Mechanistic Understanding of Perovskite LaNiO3 Nanorods as Viable, Supportless Oxygen Evolution Reaction Catalysts in Alkaline Media.

PubMed

McBean, Coray L; Liu, Haiqing; Scofield, Megan E; Li, Luyao; Wang, Lei; Bernstein, Ashley; Wong, Stanislaus S

2017-07-26

The oxygen evolution reaction (OER) is a key reaction for water electrolysis cells and air-powered battery applications. However, conventional metal oxide catalysts, used for high-performing OER, tend to incorporate comparatively expensive and less abundant precious metals such as Ru and Ir, and, moreover, suffer from poor stability. To attempt to mitigate for all of these issues, we have prepared one-dimensional (1D) OER-active perovskite nanorods using a unique, simple, generalizable, and robust method. Significantly, our work demonstrates the feasibility of a novel electroless, seedless, surfactant-free, wet solution-based protocol for fabricating "high aspect ratio" LaNiO 3 and LaMnO 3 nanostructures. As the main focus of our demonstration of principle, we prepared as-synthesized LaNiO 3 rods and correlated the various temperatures at which these materials were annealed with their resulting OER performance. We observed generally better OER performance for samples prepared with lower annealing temperatures. Specifically, when annealed at 600 °C, in the absence of a conventional conductive carbon support, our as-synthesized LaNiO 3 rods not only evinced (i) a reasonable level of activity toward OER but also displayed (ii) an improved stability, as demonstrated by chronoamperometric measurements, especially when compared with a control sample of commercially available (and more expensive) RuO 2 .

Resistance of hypoxic cells to ionizing radiation is influenced by homologous recombination status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprong, Debbie; Janssen, Hilde L.; Vens, Conchita

2006-02-01

Purpose: To determine the role of DNA repair in hypoxic radioresistance. Methods and Materials: Chinese hamster cell lines with mutations in homologous recombination (XRCC2, XRCC3, BRAC2, RAD51C) or nonhomologous end-joining (DNA-PKcs) genes were irradiated under normoxic (20% oxygen) and hypoxic (<0.1% oxygen) conditions, and the oxygen enhancement ratio (OER) was calculated. In addition, Fanconi anemia fibroblasts (complementation groups C and G) were compared with fibroblasts from nonsyndrome patients. RAD51 foci were studied using immunofluorescence. Results: All hamster cell lines deficient in homologous recombination showed a decrease in OER (1.5-2.0 vs. 2.6-3.0 for wild-types). In contrast, the OER for the DNA-PKcs-deficientmore » line was comparable to wild-type controls. The two Fanconi anemia cell strains also showed a significant reduction in OER. The OER for RAD51 foci formation at late times after irradiation was considerably lower than that for survival in wild-type cells. Conclusion: Homologous recombination plays an important role in determining hypoxic cell radiosensitivity. Lower OERs have also been reported in cells deficient in XPF and ERCC1, which, similar to homologous recombination genes, are known to play a role in cross-link repair. Because Fanconi anemia cells are also sensitive to cross-linking agents, this strengthens the notion that the capacity to repair cross-links determines hypoxic radiosensitivity.« less

Trends in activity for the oxygen evolution reaction on transition metal (M = Fe, Co, Ni) phosphide pre-catalysts† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc05033j

PubMed Central

Xu, Junyuan; Li, Junjie; Xiong, Dehua; Zhang, Bingsen; Liu, Yuefeng; Wu, Kuang-Hsu; Amorim, Isilda; Li, Wei

2018-01-01

Transition metal phosphides (TMPs) have recently emerged as a new class of pre-catalysts that can efficiently catalyze the oxygen evolution reaction (OER). However, how the OER activity of TMPs varies with the catalyst composition has not been systematically explored. Here, we report the alkaline OER electrolysis of a series of nanoparticulate phosphides containing different equimolar metal (M = Fe, Co, Ni) components. Notable trends in OER activity are observed, following the order of FeP < NiP < CoP < FeNiP < FeCoP < CoNiP < FeCoNiP, which indicate that the introduction of a secondary metal(s) to a mono-metallic TMP substantially boosts the OER performance. We ascribe the promotional effect to the enhanced oxidizing power of bi- and tri-metallic TMPs that can facilitate the formation of MOH and chemical adsorption of OH– groups, which are the rate-limiting steps for these catalysts according to our Tafel analysis. Remarkably, the tri-metallic FeCoNiP pre-catalyst exhibits exceptionally high apparent and intrinsic OER activities, requiring only 200 mV to deliver 10 mA cm–2 and showing a high turnover frequency (TOF) of ≥0.94 s–1 at the overpotential of 350 mV. PMID:29780476

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Zhiyi; Chen, Guangxu; Li, Yanbin

Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces andmore » their OER activities can be understood by the increase of Co 4+ sites relative to Co 3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm –2) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.« less

Understanding interactions between manganese oxide and gold that lead to enhanced activity for electrocatalytic water oxidation.

PubMed

Gorlin, Yelena; Chung, Chia-Jung; Benck, Jesse D; Nordlund, Dennis; Seitz, Linsey; Weng, Tsu-Chien; Sokaras, Dimosthenis; Clemens, Bruce M; Jaramillo, Thomas F

2014-04-02

To develop active nonprecious metal-based electrocatalysts for the oxygen evolution reaction (OER), a limiting reaction in several emerging renewable energy technologies, a deeper understanding of the activity of the first row transition metal oxides is needed. Previous studies of these catalysts have reported conflicting results on the influence of noble metal supports on the OER activity of the transition metal oxides. Our study aims to clarify the interactions between a transition metal oxide catalyst and its metal support in turning over this reaction. To achieve this goal, we examine a catalytic system comprising nanoparticulate Au, a common electrocatalytic support, and nanoparticulate MnO(x), a promising OER catalyst. We conclusively demonstrate that adding Au to MnO(x) significantly enhances OER activity relative to MnO(x) in the absence of Au, producing an order of magnitude higher turnover frequency (TOF) than the TOF of the best pure MnO(x) catalysts reported to date. We also provide evidence that it is a local rather than bulk interaction between Au and MnO(x) that leads to the observed enhancement in the OER activity. Engineering improvements in nonprecious metal-based catalysts by the addition of Au or other noble metals could still represent a scalable catalyst as even trace amounts of Au are shown to lead a significant enhancement in the OER activity of MnO(x).

MOF derived Ni/Co/NC catalysts with enhanced properties for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Hu, Jiapeng; Chen, Juan; Lin, Hao; Liu, Ruilai; Yang, Xiaobing

2018-03-01

Designing efficient electrocatalysts for oxygen evolution reaction (OER) is very important for renewable energy storage and conversion devices. In this paper, we introduced a new strategy to synthesize Ni doped Co/NC catalysts (NC is the abbreviation of nitrogen-doped graphitic carbon), which were derived from ZIF-67. All catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and oxygen evolution reaction (OER). The results show that Ni was well doped in the Ni/Co/NC catalysts and the doping of Ni has great influence on the OER activity of Ni/Co/NC catalysts. Among these catalysts, 0.50Ni/Co/NC exhibits the highest OER activity. The onset potential of 0.50Ni/Co/NC is 1.47 V, which is superior than the onset potential of Co/NC (1.54 V), 0.25Ni/Co/NC (1.48 V), 1.00Ni/Co/NC (1.53 V). The excellent OER activity of 0.50Ni/Co/NC catalyst makes its potential to be used on renewable energy storage.

Experimental and Computational Evidence of Highly Active Fe Impurity Sites on the Surface of Oxidized Au for the Electrocatalytic Oxidation of Water in Basic Media

DOE PAGES

Klaus, Shannon; Trotochaud, Lena; Cheng, Mu-Jeng; ...

2015-10-22

Addition of Fe to Ni- and Co-based (oxy)hydroxides has been shown to enhance the activity of these materials for electrochemical oxygen evolution. Here we show that Fe cations bound to the surface of oxidized Au exhibit enhanced oxygen evolution reaction (OER) activity. We find that the OER activity increases with increasing surface concentration of Fe. Density functional theory analysis of the OER energetics reveals that oxygen evolution over Fe cations bound to a hydroxyl-terminated oxidized Au (Fe-Au 2O 3) occurs at an overpotential ~0.3V lower than over hydroxylated Au 2O 3 (0.82V). This finding agrees well with experimental observations andmore » is a consequence of the more optimal binding energetics of OER reaction intermediates at Fe cations bound to the surface of Au 2O 3. These findings suggest that the enhanced OER activity reported recently upon low-potential cycling of Au may be due to surface Fe impurities rather than to "superactive" Au(III) surfaquo species.« less

Water Splitting by Thin Film Metal-Oxo Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nocera, Daniel

2013-03-15

The dropping price of silicon photovoltaics in the United States is causing load defection to solar supply at an accelerated pace. This conversion to solar and, more generally, other renewable energy sources has accordingly turned the energy research focus from generation to one of storage. Truly disruptive improvements in energy storage technologies are limited by energy density. This limitation, however, does not apply to fuels, which possess the energy density needed for large-scale energy storage. The first step of the basic science needed to drive such historic restructuring of the U.S. energy infrastructure begins with the solar-driven generation of hydrogenmore » and oxygen from water. The solar-produced hydrogen may then be combined with carbon dioxide to deliver any number of fuels. Obviously, light does not directly act on water to engender its splitting into its elemental components. Hence, catalysts are needed to drive the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Of these two reactions, the four-electron, four-proton oxidation of OER is the more kinetically challenging reaction, and therefore the development of energy efficient solar fuels processes demands that OER be accomplished at a minimal overpotential. The research completed in this program developed catalysts that drive OER and at the same time meet the important criteria of (1) using non-critical materials that (2) are easy to assemble and (3) accomplish OER under simple conditions. Research was designed to uncover the chemical principles that underlie the self-assembly of metal oxide oxygen evolving catalysts (M-OEC) from the metals of M = Mn, Co, and Ni. For example, a dogma of heterogeneous catalysis of any sort is that “edges” matter in promoting catalytic transformations. We provided a rationale for such dogma by showing that the OER in Co-OEC occurred at a dimensionally reduced dicobalt edge site. Edge site reactivity was clearly revealed analyzing 18O labeled OER with differential electrochemical mass spectrometry (DEMS) of Co-OEC. The OER mechanism of M-OECs was examined with complementary studies of model dicobalt compounds that captured the critical steps of the OER reaction. Additionally, the role of activating M-OECS with metal ion dopants was defined by developing structure–function relationships, guided by the principles of inorganic chemistry. We found that the M(IV) oxidation state in oxidic OER frameworks was correlated to the presence of the dopant metal, as assessed by coulometric titration and ICP-MS analysis. To investigate why greater M(IV) valence is beneficial to greater catalytic OER activity, we probed the influence of formal M valence on the electronic structure of oxygen ions in M-OECs by undertaking O and Ni K-edge spectroscopy, which revealed greater M-O covalency and hence M-oxyl radical character with M(IV) formation. Such oxyl radical character is consistent with increasing evidence for the role of oxygen radicals in O–O bond formation by a proton-coupled electron transfer mechanism involving water, to generate a hydroperoxide intermediate from which oxygen is generate. In accomplishing this science, the DOE program leveraged its expertise in spectroscopy and structural methods, inorganic and materials synthesis, and electrochemical characterization. The knowledge garnered from this proposed program enables the design of next generation catalysts with improved OER kinetics that operate over a wide range of conditions and environments.« less

Identifying the Active Surfaces of Electrochemically Tuned LiCoO 2 for Oxygen Evolution Reaction

DOE PAGES

Lu, Zhiyi; Chen, Guangxu; Li, Yanbin; ...

2017-04-18

Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces andmore » their OER activities can be understood by the increase of Co 4+ sites relative to Co 3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm –2) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.« less

Generalizable, Electroless, Template-Assisted Synthesis and Electrocatalytic Mechanistic Understanding of Perovskite LaNiO 3 Nanorods as Viable, Supportless Oxygen Evolution Reaction Catalysts in Alkaline Media

DOE PAGES

McBean, Coray L.; Liu, Haiqing; Scofield, Megan E.; ...

2017-07-17

We present that the oxygen evolution reaction (OER) is a key reaction for water electrolysis cells and air-powered battery applications. However, conventional metal oxide catalysts, used for high-performing OER, tend to incorporate comparatively expensive and less abundant precious metals such as Ru and Ir, and, moreover, suffer from poor stability. To attempt to mitigate for all of these issues, we have prepared one-dimensional (1D) OER-active perovskite nanorods using a unique, simple, generalizable, and robust method. Significantly, our work demonstrates the feasibility of a novel electroless, seedless, surfactant-free, wet solution-based protocol for fabricating “high aspect ratio” LaNiO 3 and LaMnO 3more » nanostructures. As the main focus of our demonstration of principle, we prepared as-synthesized LaNiO 3 rods and correlated the various temperatures at which these materials were annealed with their resulting OER performance. In addition, we observed generally better OER performance for samples prepared with lower annealing temperatures. Specifically, when annealed at 600 °C, in the absence of a conventional conductive carbon support, our as-synthesized LaNiO 3 rods not only evinced (i) a reasonable level of activity toward OER but also displayed (ii) an improved stability, as demonstrated by chronoamperometric measurements, especially when compared with a control sample of commercially available (and more expensive) RuO 2.« less

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An investigation of thin-film Ni-Fe oxide catalysts for the electrochemical evolution of oxygen.

PubMed

Louie, Mary W; Bell, Alexis T

2013-08-21

A detailed investigation has been carried out of the structure and electrochemical activity of electrodeposited Ni-Fe films for the oxygen evolution reaction (OER) in alkaline electrolytes. Ni-Fe films with a bulk and surface composition of 40% Fe exhibit OER activities that are roughly 2 orders of magnitude higher than that of a freshly deposited Ni film and about 3 orders of magnitude higher than that of an Fe film. The freshly deposited Ni film increases in activity by as much as 20-fold during exposure to the electrolyte (KOH); however, all films containing Fe are stable as deposited. The oxidation of Ni(OH)2 to NiOOH in Ni films occurs at potentials below the onset of the OER. Incorporation of Fe into the film increases the potential at which Ni(OH)2/NiOOH redox occurs and decreases the average oxidation state of Ni in NiOOH. The Tafel slope (40 mV dec(-1)) and reaction order in OH(-) (1) for the mixed Ni-Fe films (containing up to 95% Fe) are the same as those for aged Ni films. In situ Raman spectra acquired in 0.1 M KOH at OER potentials show two bands characteristic of NiOOH. The relative intensities of these bands vary with Fe content, indicating a change in the local environment of Ni-O. Similar changes in the relative intensities of the bands and an increase in OER activity are observed when pure Ni films are aged. These observations suggest that the OER is catalyzed by Ni in Ni-Fe films and that the presence of Fe alters the redox properties of Ni, causing a positive shift in the potential at which Ni(OH)2/NiOOH redox occurs, a decrease in the average oxidation state of the Ni sites, and a concurrent increase in the activity of Ni cations for the OER.

A new visual navigation system for exploring biomedical Open Educational Resource (OER) videos

PubMed Central

Zhao, Baoquan; Xu, Songhua; Lin, Shujin; Luo, Xiaonan; Duan, Lian

2016-01-01

Objective Biomedical videos as open educational resources (OERs) are increasingly proliferating on the Internet. Unfortunately, seeking personally valuable content from among the vast corpus of quality yet diverse OER videos is nontrivial due to limitations of today’s keyword- and content-based video retrieval techniques. To address this need, this study introduces a novel visual navigation system that facilitates users’ information seeking from biomedical OER videos in mass quantity by interactively offering visual and textual navigational clues that are both semantically revealing and user-friendly. Materials and Methods The authors collected and processed around 25 000 YouTube videos, which collectively last for a total length of about 4000 h, in the broad field of biomedical sciences for our experiment. For each video, its semantic clues are first extracted automatically through computationally analyzing audio and visual signals, as well as text either accompanying or embedded in the video. These extracted clues are subsequently stored in a metadata database and indexed by a high-performance text search engine. During the online retrieval stage, the system renders video search results as dynamic web pages using a JavaScript library that allows users to interactively and intuitively explore video content both efficiently and effectively. Results The authors produced a prototype implementation of the proposed system, which is publicly accessible at https://patentq.njit.edu/oer. To examine the overall advantage of the proposed system for exploring biomedical OER videos, the authors further conducted a user study of a modest scale. The study results encouragingly demonstrate the functional effectiveness and user-friendliness of the new system for facilitating information seeking from and content exploration among massive biomedical OER videos. Conclusion Using the proposed tool, users can efficiently and effectively find videos of interest, precisely locate video segments delivering personally valuable information, as well as intuitively and conveniently preview essential content of a single or a collection of videos. PMID:26335986

In-situ confined formation of NiFe layered double hydroxide quantum dots in expanded graphite for active electrocatalytic oxygen evolution

NASA Astrophysics Data System (ADS)

Guo, Jinxue; Li, Xiaoyan; Sun, Yanfang; Liu, Qingyun; Quan, Zhenlan; Zhang, Xiao

2018-06-01

Development of noble-metal-free catalysts towards highly efficient electrochemical oxygen evolution reaction (OER) is critical but challenging in the renewable energy area. Herein, we firstly embed NiFe LDHs quantum dots (QDs) into expanded graphite (NiFe LDHs/EG) via in-situ confined formation process. The interlayer spacing of EG layers acts as nanoreactors for spatially confined formation of NiFe LDHs QDs. The QDs supply huge catalytic sites for OER. The in-situ decoration endows the strong affinity between QDs with EG, thus inducing fast charge transfer. Based on the aforementioned benefits, the designed catalyst exhibits outstanding OER properties, in terms of small overpotential (220 mV required to generate 10 mA cm-2), low Tafel slope, and good durable stability, making it a promising candidate for inexpensive OER catalyst.

Theoretical Insights to Bulk Activity Towards Oxygen Evolution in Oxyhydroxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doyle, Andrew D.; Bajdich, Michal; Vojvodic, Aleksandra

The nature of the electrochemical water splitting activity of layered pure and Fe-doped NiOOH is investigated using density functional theory calculations. We find similar thermodynamics for the oxygen evolution reaction (OER) intermediates between the layers of oxyhydroxides, that is, in the bulk of the materials as on the (001) surface. The effect of interlayer spacing on adsorption energy is affected by both the crystal structure and the level of hydrogenation of the active sites. For the Fe-doped NiOOH, we observe general weakening of binding between the different OER intermediates and the catalyst material. The calculated OER activity depends both onmore » doping and interlayer spacing, and our results are generally congruent with available experimental data. In conclusion, these results suggest that such interlayer “bulk” sites may contribute to measured OER activity for both the pure and Fe-doped NiOOH catalysts.« less

Theoretical Insights to Bulk Activity Towards Oxygen Evolution in Oxyhydroxides

DOE PAGES

Doyle, Andrew D.; Bajdich, Michal; Vojvodic, Aleksandra

2017-04-07

The nature of the electrochemical water splitting activity of layered pure and Fe-doped NiOOH is investigated using density functional theory calculations. We find similar thermodynamics for the oxygen evolution reaction (OER) intermediates between the layers of oxyhydroxides, that is, in the bulk of the materials as on the (001) surface. The effect of interlayer spacing on adsorption energy is affected by both the crystal structure and the level of hydrogenation of the active sites. For the Fe-doped NiOOH, we observe general weakening of binding between the different OER intermediates and the catalyst material. The calculated OER activity depends both onmore » doping and interlayer spacing, and our results are generally congruent with available experimental data. In conclusion, these results suggest that such interlayer “bulk” sites may contribute to measured OER activity for both the pure and Fe-doped NiOOH catalysts.« less

MO-Co@N-Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn-Air Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Biaohua; He, Xiaobo; Yin, Fengxiang

A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal-air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO-Co@ N-doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal-organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co-N-xmore » and Co3+/Co2+ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn-based and Co-based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (>= 700 degrees C), which is favorable for charge transfer. The optimized CoZn-NC-700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO2 (for OER). CoZn-NC-700 also exhibits the prominent Zn-air battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO2.« less

75 FR 82377 - NOAA's Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015

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2010-12-30

.... Data and observations resulting from OER investments will result in new discoveries, insights, knowledge and identification of new frontiers, and will likely lead to new or revised understandings of our...

Design of template-stabilized active and earth-abundant oxygen evolution catalysts in acid† †Electronic supplementary information (ESI) available: CVs for unary metal oxides deposition, electrochemical stability at higher current densities for unary metal oxides at pH 2.5, EDS maps for CoMnOx and CoPbOx, STEM images and PXRD of CoMnOx and CoFePbOx, high-resolution XPS of Fe 2p for CoFePbOx, Pourbaix diagrams (of Mn, Co, Pb, and Fe), and elemental analysis. See DOI: 10.1039/c7sc01239j Click here for additional data file.

PubMed Central

Huynh, Michael; Ozel, Tuncay; Liu, Chong; Lau, Eric C.

2017-01-01

Oxygen evolution reaction (OER) catalysts that are earth-abundant and are active and stable in acid are unknown. Active catalysts derived from Co and Ni oxides dissolve at low pH, whereas acid stable systems such as Mn oxides (MnOx) display poor OER activity. We now demonstrate a rational approach for the design of earth-abundant catalysts that are stable and active in acid by treating activity and stability as decoupled elements of mixed metal oxides. Manganese serves as a stabilizing structural element for catalytically active Co centers in CoMnOx films. In acidic solutions (pH 2.5), CoMnOx exhibits the OER activity of electrodeposited Co oxide (CoOx) with a Tafel slope of 70–80 mV per decade while also retaining the long-term acid stability of MnOx films for OER at 0.1 mA cm–2. Driving OER at greater current densities in this system is not viable because at high anodic potentials, Mn oxides convert to and dissolve as permanganate. However, by exploiting the decoupled design of the catalyst, the stabilizing structural element may be optimized independently of the Co active sites. By screening potential–pH diagrams, we replaced Mn with Pb to prepare CoFePbOx films that maintained the high OER activity of CoOx at pH 2.5 while exhibiting long-term acid stability at higher current densities (at 1 mA cm–2 for over 50 h at pH 2.0). Under these acidic conditions, CoFePbOx exhibits OER activity that approaches noble metal oxides, thus establishing the viability of decoupling functionality in mixed metal catalysts for designing active, acid-stable, and earth-abundant OER catalysts. PMID:29163926

Evidence that the oxygen enhancement ratio for pink somatic mutations in Tradescantia stamen hairs may approach unity at very low x-ray doses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Underbrink, A.G.; Woch, B.

1980-11-01

Experimental evidence was found that the oxygen enhancement ratio (OER) for pink somatic mutations in the stamen hairs of Tradescantia clone 02 appears to reach unity at X-ray doses of 2 to 3 rad. There is also a small segment on the dose-response curves from about 3 to 10 rad where the OER appears to be dose-dependent. At higher doses the aerated and hypoxic curves are parallel, and the OER is 3.2 up to doses where the mutation frequency reaches a plateau.

Porous Cobalt Phosphide Polyhedrons with Iron Doping as an Efficient Bifunctional Electrocatalyst.

PubMed

Li, Feng; Bu, Yunfei; Lv, Zijian; Mahmood, Javeed; Han, Gao-Feng; Ahmad, Ishfaq; Kim, Guntae; Zhong, Qin; Baek, Jong-Beom

2017-10-01

Iron (Fe)-doped porous cobalt phosphide polyhedrons are designed and synthesized as an efficient bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The synthesis strategy involves one-step route for doping foreign metallic element and forming porous cobalt phosphide polyhedrons. With varying doping levels of Fe, the optimized Fe-doped porous cobalt phosphide polyhedron exhibits significantly enhanced HER and OER performances, including low onset overpotentials, large current densities, as well as small Tafel slopes and good electrochemical stability during HER and OER. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring the kinetic and thermodynamic aspects of four-electron electrochemical reactions: electrocatalysis of oxygen evolution by metal oxides and biological systems.

PubMed

Wang, Vincent C-C

2016-08-10

Finding fundamental and general mechanisms for electrochemical reactions, such as the oxygen evolution reaction (OER) from water and reduction of CO2, plays vital roles in developing the desired electrocatalysts for facilitating solar fuel production. Recently, density functional theory (DFT) calculations have shown that there is a universal scaling relation of adsorption energy between key intermediate species, HO(ad) and HOO(ad), on the surface of metal oxides as OER electrocatalysts. In this paper, a kinetic and thermodynamic model for the four-electron electrochemical reaction based on previous OER mechanisms proposed by DFT calculations is developed to further investigate the electrocatalytic properties over a wide range of metal oxides and photosystem II. The OER activity of metal oxides (i.e. electrocatalytic current) calculated from the DFT-calculated equilibrium potentials with kinetic properties, such as the rate constants for interfacial electron transfer and catalytic turnover, can lead to a volcano-shaped trend that agrees with the results observed in experiments. In addition, the kinetic aspects of the impact on the electrocatalysts are evaluated. Finally, comparing the results of metal oxides and photosystem II, and fitting experimental voltammograms give further insights into kinetic and thermodynamic roles. Here, the general guidelines for designing OER electrocatalysts with unified kinetic and thermodynamic properties are presented.

"Open-Sourcing" Personal Learning

ERIC Educational Resources Information Center

Fiedler, Sebastian H.D.

2014-01-01

This article offers a critical reflection on the contemporary Open Educational Resource (OER) movement, its unquestioned investment in a collective "content fetish" and an educational "problem description" that focuses on issues of scarcity, access, and availability of quality materials. It also argues that OER proponents fail…

Spontaneous Water Oxidation at Hematite (α-Fe2O3) Crystal Faces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatman, Shawn ME; Zarzycki, Piotr P.; Rosso, Kevin M.

2015-01-28

Hematite (α-Fe2O3) persists as a promising candidate for photoelectrochemical water splitting but a slow oxygen evolution reaction (OER) at its surfaces remains a limitation. Here we extend a series of studies that examine pH-dependent surface potentials and electron transfer properties of effectively perfect low-index crystal faces of hematite in contact with simple electrolyte. Zero resistance amperometry was performed in a two electrode configuration to quantify spontaneous dark current between hematite crystal face pairs (001)/(012), (001)/(113), and (012)/(113) at pH 3. Exponentially decaying currents initially of up to 200 nA were reported between faces over four minute experiments. Fourth order ZRAmore » kinetics indicated rate limitation by the OER for current that flows between (001)/(012) and (001)/(113) face pairs, with the (012) and (113) faces serving as the anodes when paired with (001). The cathodic partner reaction is reductive dissolution of the (001) face, converting surface Fe3+ to solubilized aqueous Fe2+, at a rate maintained by the OER at the anode. In contrast, OER rate limitation does not manifest for the (012)/(113) pair. The uniqueness of the (001) face is established in terms of a faster intrinsic ability to accept the protons required for the reductive dissolution reaction. OER rate limitation inversely may thus arise from sluggish kinetics of hematite surfaces to dispense with the protons that accompany the four-electron OER. The results are explained in terms of semi-quantitative energy band diagrams. The finding may be useful as a consideration for tailoring the design of polycrystalline hematite photoanodes that present multiple terminations to the interface with electrolyte.« less

Coping with unpredictability: dopaminergic and neurotrophic responses to omission of expected reward in Atlantic salmon (Salmo salar L.).

PubMed

Vindas, Marco A; Sørensen, Christina; Johansen, Ida B; Folkedal, Ole; Höglund, Erik; Khan, Uniza W; Stien, Lars H; Kristiansen, Tore S; Braastad, Bjarne O; Øverli, Øyvind

2014-01-01

Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward') causes increased aggression in Atlantic salmon (Salmo salar). Here we report changes in brain monoaminergic activity and relative abundance of brain derived neurotrophic factor (BDNF) and dopamine receptor mRNA transcripts in the same paradigm. Groups of fish were initially conditioned to associate a flashing light with feeding. Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT) or dopamine (DA) activity. Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1) mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition OER suppressed abundance of BDNF in the telencephalon of non-stressed fish. Regardless of OER treatment, a strong positive correlation between BDNF and D1 mRNA abundance was seen in non-stressed fish. This correlation was disrupted by acute stress, and replaced by a negative correlation between BDNF abundance and plasma cortisol concentration. These observations indicate a conserved link between DA, neurotrophin regulation, and corticosteroid-signaling pathways. The results also emphasize how fish models can be important tools in the study of neural plasticity and responsiveness to environmental unpredictability.

The surface sulfur doping induced enhanced performance of cobalt catalysts in oxygen evolution reactions.

PubMed

Al-Mamun, Mohammad; Zhu, Zhengju; Yin, Huajie; Su, Xintai; Zhang, Haimin; Liu, Porun; Yang, Huagui; Wang, Dan; Tang, Zhiyong; Wang, Yun; Zhao, Huijun

2016-08-04

A novel surface sulfur (S) doped cobalt (Co) catalyst for the oxygen evolution reaction (OER) is theoretically designed through the optimisation of the electronic structure of highly reactive surface atoms which is also validated by electrocatalytic OER experiments.

A Molecular Ni-complex Containing Tetrahedral Nickel Selenide Core as Highly Efficient Electrocatalyst for Water Oxidation.

PubMed

Masud, Jahangir; Ioannou, Polydoros-Chrysovalantis; Levesanos, Nikolaos; Kyritsis, Panayotis; Nath, Manashi

2016-11-23

We report the highly efficient catalytic activity of a transition metal selenide-based coordination complex, [Ni{(SeP i Pr 2 ) 2 N} 2 ], (1) for oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solution. Very low overpotentials of 200 mV and 310 mV were required to achieve 10 mA cm -2 for OER and HER, respectively. The overpotential for OER is one of the lowest that has been reported up to now, making this one of the best OER electrocatalysts. In addition, this molecular complex exhibits an exceptionally high mass activity (111.02 A g -1 ) and a much higher TOF value (0.26 s -1 ) at a overpotential of 300 mV. This bifunctional electrocatalyst enables water electrolysis in alkaline solutions at a cell voltage of 1.54 V. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The reaction mechanism with free energy barriers at constant potentials for the oxygen evolution reaction at the IrO 2 (110) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ping, Yuan; Nielsen, Robert J.; Goddard, William A.

How to efficiently oxidize H 2O to O 2 (oxygen evolution reaction, OER) in photoelectrochemical cells (PEC) is a great challenge due to its complex charge transfer process, high overpotential, and corrosion. So far no OER mechanism has been fully explained atomistically with both thermodynamic and kinetics. IrO 2 is the only known OER catalyst with both high catalytic activity and stability in acidic conditions. This is important because PEC experiments often operate at extreme pH conditions. In this work, we performed first-principles calculations integrated with implicit solvation at constant potentials to examine the detailed atomistic reaction mechanism of OERmore » at the IrO 2 (110) surface. We determined the surface phase diagram, explored the possible reaction pathways including kinetic barriers, and computed reaction rates based on the microkinetic models. Furthermore, this allowed us to resolve several long-standing puzzles about the atomistic OER mechanism.« less

Tuning Surface Electronic Configuration of NiFe LDHs Nanosheets by Introducing Cation Vacancies (Fe or Ni) as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction.

PubMed

Wang, Yanyong; Qiao, Man; Li, Yafei; Wang, Shuangyin

2018-04-01

Intrinsically inferior electrocatalytic activity of NiFe layered double hydroxides (LDHs) nanosheets is considered as a limiting factor to inhibit the electrocatalytic properties for oxygen evolution reaction (OER). Proper defect engineering to tune the surface electronic configuration of electrocatalysts may significantly improve the intrinsic activity. In this work, the selective formation of cation vacancies in NiFe LDHs nanosheets is successfully realized. The as-synthesized NiFe LDHs-V Fe and NiFe LDHs-V Ni electrocatalysts show excellent activity for OER, mainly attributed to the introduction of rich iron or nickel vacancies in NiFe LDHs nanosheets, which efficiently tune the surface electronic structure increasing the adsorbing capacity of OER intermediates. Density functional theory (DFT) computational results also further indicate that the OER catalytic performance of NiFe LDHs can be pronouncedly improved by introducing Fe or Ni vacancies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The reaction mechanism with free energy barriers at constant potentials for the oxygen evolution reaction at the IrO 2 (110) surface

DOE PAGES

Ping, Yuan; Nielsen, Robert J.; Goddard, William A.

2016-12-09

How to efficiently oxidize H 2O to O 2 (oxygen evolution reaction, OER) in photoelectrochemical cells (PEC) is a great challenge due to its complex charge transfer process, high overpotential, and corrosion. So far no OER mechanism has been fully explained atomistically with both thermodynamic and kinetics. IrO 2 is the only known OER catalyst with both high catalytic activity and stability in acidic conditions. This is important because PEC experiments often operate at extreme pH conditions. In this work, we performed first-principles calculations integrated with implicit solvation at constant potentials to examine the detailed atomistic reaction mechanism of OERmore » at the IrO 2 (110) surface. We determined the surface phase diagram, explored the possible reaction pathways including kinetic barriers, and computed reaction rates based on the microkinetic models. Furthermore, this allowed us to resolve several long-standing puzzles about the atomistic OER mechanism.« less

A new visual navigation system for exploring biomedical Open Educational Resource (OER) videos.

PubMed

Zhao, Baoquan; Xu, Songhua; Lin, Shujin; Luo, Xiaonan; Duan, Lian

2016-04-01

Biomedical videos as open educational resources (OERs) are increasingly proliferating on the Internet. Unfortunately, seeking personally valuable content from among the vast corpus of quality yet diverse OER videos is nontrivial due to limitations of today's keyword- and content-based video retrieval techniques. To address this need, this study introduces a novel visual navigation system that facilitates users' information seeking from biomedical OER videos in mass quantity by interactively offering visual and textual navigational clues that are both semantically revealing and user-friendly. The authors collected and processed around 25 000 YouTube videos, which collectively last for a total length of about 4000 h, in the broad field of biomedical sciences for our experiment. For each video, its semantic clues are first extracted automatically through computationally analyzing audio and visual signals, as well as text either accompanying or embedded in the video. These extracted clues are subsequently stored in a metadata database and indexed by a high-performance text search engine. During the online retrieval stage, the system renders video search results as dynamic web pages using a JavaScript library that allows users to interactively and intuitively explore video content both efficiently and effectively.ResultsThe authors produced a prototype implementation of the proposed system, which is publicly accessible athttps://patentq.njit.edu/oer To examine the overall advantage of the proposed system for exploring biomedical OER videos, the authors further conducted a user study of a modest scale. The study results encouragingly demonstrate the functional effectiveness and user-friendliness of the new system for facilitating information seeking from and content exploration among massive biomedical OER videos. Using the proposed tool, users can efficiently and effectively find videos of interest, precisely locate video segments delivering personally valuable information, as well as intuitively and conveniently preview essential content of a single or a collection of videos. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

NOAA Office of Exploration and Research > Education > Evaluation

Science.gov Websites

INFORMATION ON THE NOAA OFFICE OF OCEAN EXPLORATION AND RESEARCH, VISIT: OCEANEXPLORER.NOAA.GOV weather oceans fisheries charting satellites climate research coasts careers@noaa OER Banner Home About OER Overview of partnering institutions or Alliances Partners. Surveys containing quantitative and qualitative

Capacity-Building in Open Education: An Australian Approach

ERIC Educational Resources Information Center

Bossu, Carina; Fountain, Wendy

2015-01-01

Addressing the gap between global open educational resource (OER) proliferation and the slow adoption of OER and open educational practices (OEP) in Australian higher education, this paper focuses on a capacity-building project targeting academics, academic support staff and educational developers. The conception, design, development, piloting and…

Leading the Maricopa Millions OER Project

ERIC Educational Resources Information Center

Raneri, April; Young, Lisa

2016-01-01

With a reduced number of students purchasing required and necessary textbooks, higher education leaders must look to new opportunities to increase student success. While open educational resources have addressed this issue, they have not received widespread support from faculty, staff, and administrators. The Maricopa Millions OER Project: Scaling…

Faculty Members' Instructional Priorities for Adopting OER

ERIC Educational Resources Information Center

Jung, Insung; Hong, Seongyoun

2016-01-01

This study aimed to investigate and classify faculty members' instructional priorities for adopting OER. In-depth interview data were collected from 10 faculty members from different regions and analyzed with NVivo 10. The original supposition was that the well-established instructional priorities, effectiveness, efficiency, and appeal would…

Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Zheng, Gengfeng

2015-08-01

A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE.A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE. Electronic supplementary information (ESI) available: Supporting figures, with additional SEM images, EDS spectra, N2 sorption isotherms, charge-discharge curves, cycling performance, Ragone plot, Nyquist plots and linear scan voltammogram plots. See DOI: 10.1039/c5nr04603c

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Daojin; Cai, Zhao; Bi, Yongmin

Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotentialmore » of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. Finally, this increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.« less

Self-assembly of cobalt-centered metal organic framework and multiwalled carbon nanotubes hybrids as a highly active and corrosion-resistant bifunctional oxygen catalyst

NASA Astrophysics Data System (ADS)

Fang, Yiyun; Li, Xinzhe; Li, Feng; Lin, Xiaoqing; Tian, Min; Long, Xuefeng; An, Xingcai; Fu, Yan; Jin, Jun; Ma, Jiantai

2016-09-01

Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications.

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

DOE PAGES

Zhou, Daojin; Cai, Zhao; Bi, Yongmin; ...

2018-02-02

Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotentialmore » of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. Finally, this increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.« less

Activity–stability relationship in the surface electrochemistry of the oxygen evolution reaction

DOE PAGES

Chang, Seo Hyoung; Connell, Justin G.; Danilovic, Nemanja; ...

2014-07-25

Understanding the functional links between the stability and reactivity of oxide materials during the oxygen evolution reaction (OER) is one key to enabling a vibrant hydrogen economy capable of competing with fossil fuel-based technologies. In this work, by focusing on the surface chemistry of monometallic Ru oxide in acidic and alkaline environments, we found that the kinetics of the OER are almost entirely controlled by the stability of the Ru surface atoms. The same activity–stability relationship was found for more complex, polycrystalline and single-crystalline SrRuO 3 thin films in alkaline solutions. We propose that the electrochemical transformation of either watermore » (acidic solutions) or hydroxyl ions (alkaline solutions) to di-oxygen molecules takes place at defect sites that are inherently present on every electrode surface. During the OER, surface defects are also created by the corrosion of the Ru ions. The dissolution is triggered by the potential-dependent change in the valence state ( n) of Ru: from stable but inactive Ru 4+ to unstable but active Ru n>4+. We conclude that if the oxide is stable then it is completely inactive for the OER. As a result, a practical consequence is that the best materials for the OER should balance stability and activity in such a way that the dissolution rate of the oxide is neither too fast nor too slow.« less

Influencing Factors in OER Usage of Adult Learners in Korea

ERIC Educational Resources Information Center

Kim, Byoung Wook; Lee, Won Gyu; Lee, Byeong Rae; Shon, Jin Gon

2015-01-01

Open Educational Resources (OER) is terminology that refers to educational resources (content and software) distributed through the Internet, free of charge and freely accessible, expanding learning opportunities for adult learners. This terminology first appeared around 2002, although its roots can be traced to the open architecture of the…

OER and the Value of Openness: Implications for the Knowledge Economy

ERIC Educational Resources Information Center

Bernstein, Samantha

2015-01-01

The knowledge economy is marked by recent trends in technological advancement, globalisation and increasing knowledge intensity. Through new technologies like Open Educational Resources (OER), knowledge can be freely accessed by individuals around the world, blurring traditional notions of ownership and prompting a social transformation manifested…

Writing Commons: A Model for the Creation, Usability, and Evaluation of OERs

ERIC Educational Resources Information Center

Herron, Josh

2016-01-01

As Open Educational Resources (OER) increasingly receive attention from academics, educational foundations, and government agencies, exemplars will emerge that lower student textbook costs by moving away from commercial publishers through self-publishing or curating web-based resources. Joe Moxley's "Writing Commons" serves as a scaled…

75 FR 3449 - Office of Innovation and Improvement; Overview Information; Teaching American History Grant...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-21

... Educational Resources (OER). OER are teaching, learning, and research resources that reside in the public... traditional American history content, proven teaching strategies, and lessons learned in implementing TAH... students. The applicant is encouraged to address how its proposed professional development strategy will...

Strategic Implementation of Open Educational Resources in Higher Education Institutions

ERIC Educational Resources Information Center

Jung, Eulho; Bauer, Christine; Heaps, Allan

2017-01-01

Higher education institutions have been playing a pivotal role in the emergence and elaboration of the Open Educational Resources (OER) movement. Initially, pioneering institutions such as the Massachusetts Institute of Technology (MIT) have led the conceptualization of OER, providing models of sustainable initiatives. Following the forerunners,…

OER Use in Intermediate Language Instruction: A Case Study

ERIC Educational Resources Information Center

Godwin-Jones, Robert

2017-01-01

This paper reports on a case study in the experimental use of Open Educational Resources (OERs) in intermediate level language instruction. The resources come from three sources: the instructor, the students, and open content repositories. The objective of this action research project was to provide student-centered learning materials, enhance…

Student Perceptions of College Faculty Who Use OER

ERIC Educational Resources Information Center

Vojtech, Gabrielle; Grissett, Judy

2017-01-01

Research indicates that students find open educational resources (OER) favorable, but there is no research regarding students' perceptions of faculty who use open textbooks. In the present study we examined this topic experimentally with two undergraduate psychology courses at a small public university. Participants read two passages--one about an…

Open Access Scholarly Publications as OER

ERIC Educational Resources Information Center

Anderson, Terry

2013-01-01

This paper presents the rationale, common practices, challenges, and some personal anecdotes from a journal editor on the production, use, and re-use of peer-reviewed scholarly articles as open educational resources (OER). The scholarly and professional discourse related to open educational resources has largely focused on open learning objects,…

Multilingual Videos for MOOCs and OER

ERIC Educational Resources Information Center

Valor Miró, Juan Daniel; Baquero-Arnal, Pau; Civera, Jorge; Turró, Carlos; Juan, Alfons

2018-01-01

Massive Open Online Courses (MOOCs) and Open Educational Resources (OER) are rapidly growing, but are not usually offered in multiple languages due to the lack of cost-effective solutions to translate the different objects comprising them and particularly videos. However, current state-of-the-art automatic speech recognition (ASR) and machine…

The Promise of Open Educational Resources

ERIC Educational Resources Information Center

Smith, Marshall S.; Casserly, Catherine M.

2006-01-01

Open educational resources (OER) include full courses, course materials, modules, textbooks, streaming videos, tests, software, and any other tools, materials, or techniques used to either support access to knowledge, or have an impact on teaching, learning, and research. At the heart of the OER movement is the simple and powerful idea that the…

Metal phosphonate coordination networks and frameworks as precursors of electrocatalysts for the hydrogen and oxygen evolution reactions

NASA Astrophysics Data System (ADS)

Zhang, Rui; El-Refaei, Sayed M.; Russo, Patrícia A.; Pinna, Nicola

2018-05-01

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) play key roles in the conversion of energy derived from renewable energy sources into chemical energy. Efficient, robust, and inexpensive electrocatalysts are necessary for driving these reactions at high rates at low overpotentials and minimize energetic losses. Recently, electrocatalysts derived from hybrid metal phosphonate compounds have shown high activity for the HER or OER. We review here the utilization of metal phosphonate coordination networks and metal-organic frameworks as precursors/templates for transition-metal phosphides, phosphates, or oxyhydroxides generated in situ in alkaline solutions, and their electrocatalytic performance in HER or OER.

Women's Empowerment through Openness: OER, OEP and the Sustainable Development Goals

ERIC Educational Resources Information Center

Perryman, Leigh-Anne; de los Arcos, Beatriz

2016-01-01

This paper explores the potential of open educational resources (OER) and open educational practices (OEP) in helping achieve women's empowerment in the developing world. Our evidence comprises the Open Education Research Hub open dataset, featuring survey responses from 7,700 educators, formal and informal learners from 175 countries concerning…

Researching Resistance to Open Education Resource Contribution: An Activity Theory Approach

ERIC Educational Resources Information Center

Cox, Glenda

2013-01-01

Higher education and associated institutions are beginning to share teaching materials known as Open Educational Resources (OER) or open courseware across the globe. Their success depends largely on the willingness of academics at these institutions to add their teaching resources. In a survey of the literature on OER there are several articles…

Examining Student Perception of an Open Statistics Book

ERIC Educational Resources Information Center

Illowsky, Barbara Sack; Hilton, John, III; Whiting, Justin; Ackerman, Jordan Dale

2016-01-01

The rise of Open Educational Resources (OER) research provides data that Open Textbooks and other forms of OER may be one cost saving approach for college and university students. Yet little research has been conducted around the attitudes and perceptions of the students using these Open Textbooks. This paper examines the perceptions that students…

Open Educational Resources in Canada 2015

ERIC Educational Resources Information Center

McGreal, Rory; Anderson, Terry; Conrad, Dianne

2015-01-01

Canada's important areas of expertise in open educational resources (OER) are beginning to be built upon or replicated more broadly in all education and training sectors. This paper provides an overview of the state of the art in OER initiatives and open higher education in general in Canada, providing insights into what is happening nationally…

Understanding Social OER Environments--A Quantitative Study on Factors Influencing the Motivation to Share and Collaborate

ERIC Educational Resources Information Center

Pirkkalainen, Henri; Jokinen, Jussi P. P.; Pawlowski, Jan M.

2014-01-01

Social software environments are increasingly used for open education: teachers and learners share and collaborate in these environments. While there are various possibilities for the inclusion of such social functionalities for OER, many organizational, individual and technological challenges can hinder the motivation of teachers to share and…

Designing Capacity Building of Educators in Open Educational Resources Integration Leads to Transformational Change

ERIC Educational Resources Information Center

Karunanayaka, Shironica P.; Naidu, Som

2018-01-01

While there is growing recognition and acceptance of Open Educational Resources (OER) and Open Educational Practices (OEP) in teaching and learning, designing for their integration remains very challenging for educators. Adopting OER and OEP in their profession requires significant changes in practitioners' pedagogical thinking and practices,…

The Integration of Spirituality and Transformational Leadership in Higher Education

ERIC Educational Resources Information Center

Patton, Cheryl; Webster, Natasha; Moore-Dent, JoAnne

2017-01-01

As concerns about the skyrocketing costs of a college degree have converged with the increasing availability of open educational resources (OER), higher education administrators are asking faculty and curriculum designers to use OERs to design courses and programs. This case study explores the decision making process and outcomes of an online,…

Localizing OER in Afghanistan: Developing a Multilingual Digital Library for Afghan Teachers

ERIC Educational Resources Information Center

Oates, Lauryn; Hashimi, Jamshid

2016-01-01

The Darakht-e Danesh ("knowledge tree") Online Library is the first open educational resource (OER) initiative in Afghanistan, established to enhance teacher subject-area knowledge, access and use of learning materials, and to foster more diverse teaching methodologies in order to improve learning outcomes in Afghan classrooms. This…

State Support for Open Educational Resources: Key Findings from Achieve's OER Institute

ERIC Educational Resources Information Center

Achieve, Inc., 2013

2013-01-01

Open Educational Resources (OER) offer unique new opportunities for educators to share quality learning resources, especially in an increasingly digital world. Forty-six states and the District of Columbia have adopted the Common Core State Standards (CCSS), providing them with the unprecedented advantage of being able to share resources that are…

A Model of Digital Textbook Quality from the Perspective of College Students

ERIC Educational Resources Information Center

Bliss, T. J.

2013-01-01

The cost of textbooks is a financial burden on many college students. Fortunately the advent of open educational resources (OER) has allowed for the development of textbooks and other materials at significantly reduced costs to students. Many faculty are using OER to develop customized textbooks for their students, usually published digitally…

Framework for the Development of OER-Based Learning Materials in ODL Environment

ERIC Educational Resources Information Center

Teng, Khor Ean; Hung, Chung Sheng

2013-01-01

This paper describes the framework for the development of OER-based learning materials "TCC121/05 Programming Fundamentals with Java" for ODL learners in Wawasan Open University (WOU) using three main development phases mainly: creation, evaluation and production phases. The proposed framework has further been tested on ODL learners to…

Open Educational Resources in the Commonwealth 2016

ERIC Educational Resources Information Center

Phalachandra, B.; Abeywardena, Ishan

2016-01-01

This study was conducted as part of the OER for Skills Development project of COL, supported by The William and Flora Hewlett Foundation. The objective of the study was to collect baseline data from Commonwealth institutions with respect to the development, use and reuse of OER; the availability of support; and challenges faced in fostering the…

OER in Africa's Higher Education Institutions

ERIC Educational Resources Information Center

Ngugi, Catherine N.

2011-01-01

Higher education in Africa has had diverse histories and trajectories, and has played different roles over time. This article is concerned with the evolution and future of higher education on the continent, and the role that open educational resources (OER) might play therein. It is generally accepted that "the university in Africa and higher…

Incentivizing the Production and Use of Open Educational Resources in Higher Education Institutions

ERIC Educational Resources Information Center

Annand, David; Jensen, Tilly

2017-01-01

Substituting open educational resources (OER) for commercially-produced textbooks results in demonstrable cost savings for students in most higher education institutions. Yet OER are still not widely used, and progress toward large-scale adoption in most colleges and universities has been slow. This article reviews the literature informing…

A Federated Reference Structure for Open Informational Ecosystems

ERIC Educational Resources Information Center

Heinen, Richard; Kerres, Michael; Scharnberg, Gianna; Blees, Ingo; Rittberger, Marc

2016-01-01

The paper describes the concept of a federated ecosystem for Open Educational Resources (OER) in the German education system. Here, a variety of OER repositories (ROER) (Muuß-Merholz & Schaumburg, 2014) and reference platforms have been established in the recent past. In order to develop this ecosystem, not only are metadata standards…

The OpenCourseWare Model: High-Impact Open Educational Content

ERIC Educational Resources Information Center

Carson, Stephen

2007-01-01

OpenCourseWare (OCW) is one among several models for offering open educational resources (OER). This article explains the OCW model and its position within the broader OER context. OCW primarily represents publication of existing course materials already in use for teaching purposes. OCW projects are most often institutional, carrying the…

A Case for Authoring Multi-Touch Interactive Open Educational Resources

ERIC Educational Resources Information Center

Mills, Michael S.

2016-01-01

As textbook prices continue to skyrocket, open educational resources (OER) offer a significant way to deliver high quality content to students in higher education. The pressing issue is whether these OER are engaging, relevant, and accurate. Authoring multi-touch interactive resources that are delivered to students as open-access may not only…

A Naive Bayes Approach for Converging Learning Objects with Open Educational Resources

ERIC Educational Resources Information Center

Sabitha, A. Sai; Mehrotra, Deepti; Bansal, Abhay; Sharma, B. K.

2016-01-01

Open educational resources (OER) are digitised material freely available to the students and self learners. Many institutions had initiated in incorporating these OERs in their higher educational system, to improve the quality of teaching and learning. These resources promote individualised study, collaborative learning. If they are coupled with…

Implementation of Open Educational Resources in a Nursing Programme: Experiences and Reflections

ERIC Educational Resources Information Center

Elf, Marie; Ossiannilsson, Ebba; Neljesjö, Maria; Jansson, Monika

2015-01-01

The IMPOER project (implementation of open educational resources, OER) aimed to implement OER in a nursing programme at Dalarna University, Sweden. The university and its nursing programme have long engaged in e-learning, and the nursing programme has recently been awarded the European Association of Distance Teaching Universities E-xcellence…

AM-OER: An Agile Method for the Development of Open Educational Resources

ERIC Educational Resources Information Center

Arimoto, Maurício M.; Barroca, Leonor; Barbosa, Ellen F.

2016-01-01

Open Educational Resources have emerged as important elements of education in the contemporary society, promoting life-long and personalized learning that transcends social, economic and geographical barriers. To achieve the potential of OERs and bring impact on education, it is necessary to increase their development and supply. However, one of…

Conceptual Framework for Parametrically Measuring the Desirability of Open Educational Resources Using D-Index

ERIC Educational Resources Information Center

Abeywardena, Ishan Sudeera; Tham, Choy Yoong; Raviraja, S.

2012-01-01

Open educational resources (OER) are a global phenomenon that is fast gaining credibility in many academic circles as a possible solution for bridging the knowledge divide. With increased funding and advocacy from governmental and nongovernmental organisations paired with generous philanthropy, many OER repositories, which host a vast array of…

The RISE Framework: Using Learning Analytics to Automatically Identify Open Educational Resources for Continuous Improvement

ERIC Educational Resources Information Center

Bodily, Robert; Nyland, Rob; Wiley, David

2017-01-01

The RISE (Resource Inspection, Selection, and Enhancement) Framework is a framework supporting the continuous improvement of open educational resources (OER). The framework is an automated process that identifies learning resources that should be evaluated and either eliminated or improved. This is particularly useful in OER contexts where the…

Open Educational Practices and Resources. OLCOS Roadmap, 2012

ERIC Educational Resources Information Center

Geser, Guntram, Ed.

2007-01-01

As a Transversal Action under the European eLearning Programme, the Open e-Learning Content Observatory Services (OLCOS) project carries out a set of activities that aim at fostering the creation, sharing and re-use of Open Educational Resources (OER) in Europe and beyond. OER are understood to comprise content for teaching and learning,…

Open Educational Resources and the Transformation of Education

ERIC Educational Resources Information Center

Tuomi, Ilkka

2013-01-01

The extremely rapid expansion of open educational resource (OER) initiatives and the millions of learners they attract can be understood as an indicator of an emerging revolution in education and learning. This article describes recent developments in this area and develops conceptual foundations for studies and policies on OER. We describe four…

Localization of Open Educational Resources (OER) in Nepal: Strategies of Himalayan Knowledge-Workers

ERIC Educational Resources Information Center

Ivins, Tiffany Zenith

2011-01-01

This dissertation examines localization of Open Educational Resources (OER) in Himalayan community technology centers of Nepal. Specifically, I examine strategies and practices that local knowledge-workers utilize in order to localize educational content for the disparate needs, interests, and ability-levels of learners in rural villages. This…

N-doped graphene layers encapsulated NiFe alloy nanoparticles derived from MOFs with superior electrochemical performance for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Feng, Yi; Yu, Xin-Yao; Paik, Ungyu

2016-09-01

Water splitting, an efficient approach for hydrogen production, is often hindered by unfavorable kinetics of oxygen evolution reaction (OER). In order to reduce the overpotential, noble metal oxides-based electrocatalysts like RuO2 and IrO2 are usually utilized. However, due to their scarcity, the development of cost-effective non-precious OER electrocatalysts with high efficiency and good stability is urgently required. Herein, we report a facile one-step annealing of metal-organic frameworks (MOFs) strategy to synthesize N-doped graphene layers encapsulated NiFe alloy nanoparticles (NiFe@C). Through tuning the nanoparticle size and calcination temperature, NiFe@C with an average size of around 16 nm obtained at 700 °C exhibits superior OER performance with an overpotential of only 281 mV at 10 mA cm-2 and high durability. The facile synthesis method and excellent electrochemical performance show great potential of NiFe@C in replacing the precious metal-based electrocatalysts in the OER.

Novel Co3O4 Nanoparticles/Nitrogen-Doped Carbon Composites with Extraordinary Catalytic Activity for Oxygen Evolution Reaction (OER)

NASA Astrophysics Data System (ADS)

Yang, Xiaobing; Chen, Juan; Chen, Yuqing; Feng, Pingjing; Lai, Huixian; Li, Jintang; Luo, Xuetao

2018-03-01

Herein, Co3O4 nanoparticles/nitrogen-doped carbon (Co3O4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co3O4/NPC composites. When applied as catalysts for the oxygen evolution reaction (OER), the M-Co3O4/NPC composites derived from the flower-like ZIF-67 showed superior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co3O4/NPC composite displayed a small over-potential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 mV dec-1, and a desirable stability. (94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co3O4/NPC composite in the OER was attributed to its favorable structure. [Figure not available: see fulltext.

N-doped graphene layers encapsulated NiFe alloy nanoparticles derived from MOFs with superior electrochemical performance for oxygen evolution reaction

PubMed Central

Feng, Yi; Yu, Xin-Yao; Paik, Ungyu

2016-01-01

Water splitting, an efficient approach for hydrogen production, is often hindered by unfavorable kinetics of oxygen evolution reaction (OER). In order to reduce the overpotential, noble metal oxides-based electrocatalysts like RuO2 and IrO2 are usually utilized. However, due to their scarcity, the development of cost-effective non-precious OER electrocatalysts with high efficiency and good stability is urgently required. Herein, we report a facile one-step annealing of metal-organic frameworks (MOFs) strategy to synthesize N-doped graphene layers encapsulated NiFe alloy nanoparticles (NiFe@C). Through tuning the nanoparticle size and calcination temperature, NiFe@C with an average size of around 16 nm obtained at 700 °C exhibits superior OER performance with an overpotential of only 281 mV at 10 mA cm−2 and high durability. The facile synthesis method and excellent electrochemical performance show great potential of NiFe@C in replacing the precious metal-based electrocatalysts in the OER. PMID:27658968

Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen.

PubMed

Liu, Mengjia; Li, Jinghong

2016-01-27

The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal-organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec(-1), and a current density of 10 mA cm(-2) at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations.

Cations in Octahedral Sites: A Descriptor for Oxygen Electrocatalysis on Transition-Metal Spinels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Chao; Feng, Zhenxing; Scherer, Günther G.

2017-04-10

Exploring efficient and low-cost electrocatalysts for the oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER) is critical for developing renewable energy technologies such as fuel cells, metal–air batteries, and water electrolyzers. A rational design of a catalyst can be guided by identifying descriptors that determine its activity. Here, a descriptor study on the ORR/OER of spinel oxides is presented. With a series of MnCo2O4, the Mn in octahedral sites is identified as an active site. This finding is then applied to successfully explain the ORR/OER activities of other transition-metal spinels, including MnxCo3-xO4 (x = 2, 2.5, 3), LixMn2O4 (x = 0.7,more » 1), XCo2O4 (X = Co, Ni, Zn), and XFe2O4 (X = Mn, Co, Ni). A general principle is concluded that the eg occupancy of the active cation in the octahedral site is the activity descriptor for the ORR/OER of spinels, consolidating the role of electron orbital filling in metal oxide catalysis.« less

Gold-supported cerium-doped NiO x catalysts for water oxidation

DOE PAGES

Ng, Jia Wei Desmond; García-Melchor, Max; Bajdich, Michal; ...

2016-04-29

Here, the development of high-performance catalysts for the oxygen-evolution reaction (OER) is paramount for cost-effective conversion of renewable electricity to fuels and chemicals. Here we report the significant enhancement of the OER activity of electrodeposited NiO x films resulting from the combined effects of using cerium as a dopant and gold as a metal support. This NiCeO x–Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts yet reported. On the basis of experimental observations and theoretical modelling, we ascribe the activity to a combination of electronic, geometric and support effects, where highlymore » active under-coordinated sites at the oxide support interface are modified by the local chemical binding environment and by doping the host Ni oxide with Ce. The NiCeO x–Au catalyst is further demonstrated in a device context by pairing it with a nickel–molybdenum hydrogen evolution catalyst in a water electrolyser, which delivers 50 mA consistently at 1.5 V over 24 h of continuous operation.« less

Subnanometer Cobalt-Hydroxide-Anchored N-Doped Carbon Nanotube Forest for Bifunctional Oxygen Catalyst.

PubMed

Kim, Ji Eun; Lim, Joonwon; Lee, Gil Yong; Choi, Sun Hee; Maiti, Uday Narayan; Lee, Won Jun; Lee, Ho Jin; Kim, Sang Ouk

2016-01-27

Electrochemical oxygen redox reactions are the crucial elements for energy conversion and storage including fuel cells and metal air batteries. Despite tremendous research efforts, developing high-efficient, low-cost, and durable bifunctional oxygen catalysts remains a major challenge. We report a new class of hybrid material consisting of subnanometer thick amorphous cobalt hydroxide anchored on NCNT as a durable ORR/OER bifunctional catalyst. Although amorphous cobalt species-based catalysts are known as good OER catalysts, hybridizing with NCNT successfully enhanced ORR activity by promoting a 4e reduction pathway. Abundant charge carriers in amorphous cobalt hydroxide are found to trigger the superior OER activity with high current density and low Tafel slope as low as 36 mV/decade. A remarkably high OER turnover frequency (TOF) of 2.3 s(-1) at an overpotential of 300 mV was obtained, one of the highest values reported so far. Moreover, the catalytic activity was maintained over 120 h of cycling. The unique subnanometer scale morphology of amorphous hydroxide cobalt species along with intimate cobalt species-NCNT interaction minimizes the deactivation of catalyst during prolonged repeated cycles.

RBE and OER within the spread-out Bragg peak for proton beam therapy: in vitro study at the Proton Medical Research Center at the University of Tsukuba

PubMed Central

Kanemoto, Ayae; Hirayama, Ryoichi; Moritake, Takashi; Furusawa, Yoshiya; Sun, Lue; Sakae, Takeji; Kuno, Akihiro; Terunuma, Toshiyuki; Yasuoka, Kiyoshi; Mori, Yutaro; Tsuboi, Koji; Sakurai, Hideyuki

2014-01-01

There are few reports on the biological homogeneity within the spread-out Bragg peak (SOBP) of proton beams. Therefore, to evaluate the relative biological effectiveness (RBE) and the oxygen enhancement ratio (OER), human salivary gland tumor (HSG) cells were irradiated at the plateau position (position A) and three different positions within a 6-cm-wide SOBP (position B, 26 mm proximal to the middle; position C, middle; position D, 26 mm distal to the middle) using 155-MeV/n proton beams under both normoxic and hypoxic conditions at the Proton Medical Research Center, University of Tsukuba, Japan. The RBE to the plateau region (RBEplateau) and the OER value were calculated from the doses corresponding to 10% survival data. Under the normoxic condition, the RBEplateau was 1.00, 0.99 and 1.09 for positions B, C and D, respectively. Under the hypoxic condition, the RBEplateau was 1.10, 1.06 and 1.12 for positions B, C and D, respectively. The OER was 2.84, 2.60, 2.63 and 2.76 for positions A, B, C and D, respectively. There were no significant differences in either the RBEplateau or the OER between these three positions within the SOBP. In conclusion, biological homogeneity need not necessarily be taken into account for treatment planning for proton beam therapy at the University of Tsukuba. PMID:24876271

Merging and Visualization of Archived Oceanographic Acoustic, Optical, and Sensor Data to Support Improved Access and Interpretation

NASA Astrophysics Data System (ADS)

Malik, M. A.; Cantwell, K. L.; Reser, B.; Gray, L. M.

2016-02-01

Marine researchers and managers routinely rely on interdisciplinary data sets collected using hull-mounted sonars, towed sensors, or submersible vehicles. These data sets can be broadly categorized into acoustic remote sensing, imagery-based observations, water property measurements, and physical samples. The resulting raw data sets are overwhelmingly large and complex, and often require specialized software and training to process. To address these challenges, NOAA's Office of Ocean Exploration and Research (OER) is developing tools to improve the discoverability of raw data sets and integration of quality-controlled processed data in order to facilitate re-use of archived oceanographic data. Majority of recently collected OER raw oceanographic data can be retrieved from national data archives (e.g. NCEI and NOAA central library). Merging of disperse data sets by scientists with diverse expertise, however remains problematic. Initial efforts at OER have focused on merging geospatial acoustic remote sensing data with imagery and water property measurements that typically lack direct geo-referencing. OER has developed `smart' ship and submersible tracks that can provide a synopsis of geospatial coverage of various data sets. Tools under development enable scientists to quickly assess the relevance of archived OER data to their respective research or management interests, and enable quick access to the desired raw and processed data sets. Pre-processing of the data and visualization to combine various data sets also offers benefits to streamline data quality assurance and quality control efforts.

In-situ X-Ray Absorption Spectroscopy (XAS) Investigation of a Bifunctional Manganese Oxide Catalyst with High Activity for Electrochemical Water Oxidation and Oxygen Reduction

PubMed Central

Benck, Jesse D.; Gul, Sheraz; Webb, Samuel M.; Yachandra, Vittal K.; Yano, Junko; Jaramillo, Thomas F.

2013-01-01

In-situ x-ray absorption spectroscopy (XAS) is a powerful technique that can be applied to electrochemical systems, with the ability to elucidate the chemical nature of electrocatalysts under reaction conditions. In this study, we perform in-situ XAS measurements on a bifunctional manganese oxide (MnOx) catalyst with high electrochemical activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Using x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS), we find that exposure to an ORR-relevant potential of 0.7 V vs. RHE produces a disordered Mn3II,III,IIIO4 phase with negligible contributions from other phases. After the potential is increased to a highly anodic value of 1.8 V vs. RHE, relevant to the OER, we observe an oxidation of approximately 80% of the catalytic thin film to form a mixed MnIII,IV oxide, while the remaining 20% of the film consists of a less oxidized phase, likely corresponding to unchanged Mn3II,III,IIIO4. XAS and electrochemical characterization of two thin film catalysts with different MnOx thicknesses reveals no significant influence of thickness on the measured oxidation states, at either ORR or OER potentials, but demonstrates that the OER activity scales with film thickness. This result suggests that the films have porous structure, which does not restrict electrocatalysis to the top geometric layer of the film. As the portion of the catalyst film that is most likely to be oxidized at the high potentials necessary for the OER is that which is closest to the electrolyte interface, we hypothesize that the MnIII,IV oxide, rather than Mn3II,III,IIIO4, is the phase pertinent to the observed OER activity. PMID:23758050

Electrocatalysis using transition metal carbide and oxide nanocrystals

NASA Astrophysics Data System (ADS)

Regmi, Yagya N.

Carbides are one of the several families of transition metal compounds that are considered economic alternatives to catalysts based on noble metals and their compounds. Phase pure transition metal carbides of group 4-6 metals, in the first three periods, were synthesized using a common eutectic salt flux synthesis method, and their electrocatalytic activities compared under uniform electrochemical conditions. Mo2C showed highest hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) activities among the nine metal carbides investigated, but all other metal carbides also showed substantial activities. All the metal carbides showed remarkable enhancement in catalytic activities as supports, when compared to traditional graphitic carbon as platinum support. Mo2C, the most active transition metal carbide electrocatalyst, was prepared using four different synthesis routes, and the synthesis route dependent activities compared. Bifunctional Mo 2C that is HER as well as oxygen evolution reaction (OER) active, was achieved when the carbide was templated on a multiwalled carbon nanotube using carbothermic reduction method. Bimetallic carbides of Fe, Co, and Ni with Mo or W were prepared using a common carbothermic reduction method. Two different stoichiometries of bimetallic carbides were obtained for each system within a 60 °C temperature window. While the bimetallic carbides showed relatively lower electrocatalytic activities towards HER and ORR in comparison to Mo2C and WC, they revealed remarkably higher OER activities than IrO2 and RuO2, the state-of-the-art OER catalysts. Bimetallic oxides of Fe, Co, and Ni with Mo and W were also prepared using a hydrothermal synthesis method and they also revealed OER activities that are much higher than RuO2 and IrO2. Additionally, the OER activities were dependent on the degree and nature of hydration in the bimetallic oxide crystal lattice, with the completely hydrated, as synthesized, cobalt molybdate and nickel molybdate showing the highest OER activities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwata, Hiromitsu, E-mail: h-iwa-ncu@nifty.com; Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya; Ogino, Hiroyuki

Purpose: To determine the relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and contribution of the indirect effect of spot scanning proton beams, passive scattering proton beams, or both in cultured cells in comparison with clinically used photons. Methods and Materials: The RBE of passive scattering proton beams at the center of the spread-out Bragg peak (SOBP) was determined from dose-survival curves in 4 cell lines using 6-MV X rays as controls. Survival of 2 cell lines after spot scanning and passive scattering proton irradiation was then compared. Biological effects at the distal end region of the SOBP were also investigated. Themore » OER of passive scattering proton beams and 6 MX X rays were investigated in 2 cell lines. The RBE and OER values were estimated at a 10% cell survival level. The maximum degree of protection of radiation effects by dimethyl sulfoxide was determined to estimate the contribution of the indirect effect against DNA damage. All experiments comparing protons and X rays were made under the same biological conditions. Results: The RBE values of passive scattering proton beams in the 4 cell lines examined were 1.01 to 1.22 (average, 1.14) and were almost identical to those of spot scanning beams. Biological effects increased at the distal end of the SOBP. In the 2 cell lines examined, the OER was 2.74 (95% confidence interval, 2.56-2.80) and 3.08 (2.84-3.11), respectively, for X rays, and 2.39 (2.38-2.43) and 2.72 (2.69-2.75), respectively, for protons (P<.05 for both cells between X rays and protons). The maximum degree of protection was significantly higher for X rays than for proton beams (P<.05). Conclusions: The RBE values of spot scanning and passive scattering proton beams were almost identical. The OER was lower for protons than for X rays. The lower contribution of the indirect effect may partly account for the lower OER of protons.« less

A Bibliometric Mapping of Open Educational Resources

ERIC Educational Resources Information Center

Zancanaro, Airton; Todesco, José Leomar; Ramos, Fernando

2015-01-01

Open educational resources (OER) is a topic that has aroused increasing interest by researchers as a powerful contribution to improve the educational system quality and openness, both in face to face and distance education. The goal of this research is to map publications related to OER, dating from 2002 to 2013, and available through the Web of…

OERScout Technology Framework: A Novel Approach to Open Educational Resources Search

ERIC Educational Resources Information Center

Abeywardena, Ishan Sudeera; Chan, Chee Seng; Tham, Choy Yoong

2013-01-01

The open educational resources (OER) movement has gained momentum in the past few years. With this new drive towards making knowledge open and accessible, a large number of OER repositories have been established and made available online throughout the world. However, the inability of existing search engines such as Google, Yahoo!, and Bing to…

Use of Open Educational Resources: How, Why and Why Not?

ERIC Educational Resources Information Center

Islim, Omer Faruk; Gurel Koybasi, Nergis A.; Cagiltay, Kursat

2016-01-01

Open Educational Resources (OER) and OpenCourseWare (OCW) target barriers of education and learning by sharing knowledge for free to benefit self-learners, educators, and students. This study aims to investigate the use of OER both as a supplementary resource for a traditional course and as a resource for self-learners. First, the attitudes and…

OER Usage by Instructional Designers and Training Managers in Corporations

ERIC Educational Resources Information Center

Merkel, Eli; Cohen, Anat

2015-01-01

Since the development of Open Educational Resources (OERs), different models regarding the usage of these resources in education have appeared in the literature. Wiley's 4-Rs model is considered to be one of the leading models. Research based on Wiley's model shows that using materials without making changes is the most common use. Compared to the…

Turkish Teachers' Awareness and Perceptions of Open Educational Resources

ERIC Educational Resources Information Center

Ozdemir, Ozgur; Bonk, Curtis J.

2017-01-01

The purpose of this study is to explore K-12 teachers' awareness of open educational resources (OER) as well as their perceptions of its potential opportunities and challenges for teaching practices. Data were gathered from 99 online survey respondents and six interviewees in this study. Findings showed that teachers are aware of OER to a certain…

There Is No Business Model for Open Educational Resources: A Business Model Approach

ERIC Educational Resources Information Center

de Langen, Frank

2011-01-01

The economic proverb "There is no such thing such as a free lunch" applies also to open educational resources (OER). In recent years, several authors have used revenue models and business models to analyse the different sources of possible funding for OER. In this article the business models of Osterwalder and Chesbrough are combined…

Open Educational Resources: A Review of Attributes for Adoption in an Online Bachelor's Degree Program

ERIC Educational Resources Information Center

Neely, Patricia; Tucker, Jan P.; Au, Angela

2016-01-01

As concerns about the skyrocketing costs of a college degree have converged with the increasing availability of open educational resources (OER), higher education administrators are asking faculty and curriculum designers to use OERs to design courses and programs. This case study explores the decision making process and outcomes of an online,…

The Brightly Illuminated Path: Facilitating an OER Program at Community College

ERIC Educational Resources Information Center

Blick, William; Marcus, Sandra

2017-01-01

The use of Open Education Resources represents a noble cause, but the idea often remains elusive for many faculty members. In 2015, librarians at Queensborough Community College of the City University of New York, implemented a campaign to promote and facilitate the use and development of OERs. The primary objective was to reduce the growing…

Opening Public Institutions: OER in North Dakota and the Nation, 2015

ERIC Educational Resources Information Center

Spilovoy, Tanya M.; Seaman, Jeff

2015-01-01

In the past year, Open Educational Resources have been a focus of policymakers and stakeholders in North Dakota. As a result, North Dakota University System (NDUS) faculty are more aware of the term open educational resources (OER) than their counterparts in national public institutions and all sectors of higher education. In addition, North…

Learning Challenges in Higher Education: An Analysis of Contradictions within Open Educational Practice

ERIC Educational Resources Information Center

Kaatrakoski, Heli; Littlejohn, Allison; Hood, Nina

2017-01-01

Open education, including the use of open educational resources (OER) and the adoption of open education practice, has the potential to challenge educators to change their practice in fundamental ways. This paper forms part of a larger study focusing on higher education educators' learning from and through their engagement with OER. The first part…

Learning and Open Educational Resources: A Psychological Perspective

ERIC Educational Resources Information Center

Terras, Melody M.; Ramsay, Judith; Boyle, Elizabeth

2013-01-01

The provision of Open Educational Resources (OER) means that learning horizons are no longer restricted by time and space. However, if the learning potential of OER is to be fully realised, educators and students must have the media literacy skills to select, use and produce information in a judicious and useful way. A consideration of the…

The oxygen enhancement ratio for single- and double-strand breaks induced by tritium incorporated in DNA of cultured human T1 cells. Impact of the transmutation effect.

PubMed

Tisljar-Lentulis, G; Henneberg, P; Feinendegen, L E; Commerford, S L

1983-04-01

The effect of oxygen, expressed as the oxygen enhancement ratio (OER), on the number of single-strand breaks (SSB) and double-strand breaks (DSB) induced in DNA by the radioactive decay of tritium was measured in human T1 cells whose DNA had been labeled with tritium at carbon atom number 6 of thymidine. Decays were accumulated in vivo under aerobic conditions at 0-1 degrees C and at -196 degrees C and in a nitrogen atmosphere at 0-1 degrees C. The number of SSB and DSB produced was analyzed by sucrose gradient centrifugation. For each tritium decay there were 0.25 DSB in cells exposed to air at 0-1 degrees C and 0.07 in cells kept under nitrogen, indicating an OER of 3.6, a value expected for such low-LET radiation. However, for each tritium decay there were 1.25 SSB in cells exposed to air at 0-1 degrees C and 0.76 in cells kept under nitrogen indicating an OER of only 1.7. The corresponding values for 60Co gamma radiation, expressed as SSB per 100 eV absorbed energy, were 4.5 and 1.0, giving an OER of 4.5. The low OER value found for SSB induced by tritium decay can be explained if 31% of the total SSB produced in air result from transmutation by a mechanism which does not produce DSB and is unaffected by oxygen.

Identification of catalytic sites for oxygen reduction and oxygen evolution in N-doped graphene materials: Development of highly efficient metal-free bifunctional electrocatalyst

PubMed Central

Yang, Hong Bin; Miao, Jianwei; Hung, Sung-Fu; Chen, Jiazang; Tao, Hua Bing; Wang, Xizu; Zhang, Liping; Chen, Rong; Gao, Jiajian; Chen, Hao Ming; Dai, Liming; Liu, Bin

2016-01-01

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to renewable energy conversion and storage technologies. Heteroatom-doped carbon nanomaterials have been reported to be efficient metal-free electrocatalysts for ORR in fuel cells for energy conversion, as well as ORR and OER in metal-air batteries for energy storage. We reported that metal-free three-dimensional (3D) graphene nanoribbon networks (N-GRW) doped with nitrogen exhibited superb bifunctional electrocatalytic activities for both ORR and OER, with an excellent stability in alkaline electrolytes (for example, KOH). For the first time, it was experimentally demonstrated that the electron-donating quaternary N sites were responsible for ORR, whereas the electron-withdrawing pyridinic N moieties in N-GRW served as active sites for OER. The unique 3D nanoarchitecture provided a high density of the ORR and OER active sites and facilitated the electrolyte and electron transports. As a result, the as-prepared N-GRW holds great potential as a low-cost, highly efficient air cathode in rechargeable metal-air batteries. Rechargeable zinc-air batteries with the N-GRW air electrode in a two-electrode configuration exhibited an open-circuit voltage of 1.46 V, a specific capacity of 873 mAh g−1, and a peak power density of 65 mW cm−2, which could be continuously charged and discharged with an excellent cycling stability. Our work should open up new avenues for the development of various carbon-based metal-free bifunctional electrocatalysts of practical significance. PMID:27152333

Regulating the active species of Ni(OH)2 using CeO2: 3D CeO2/Ni(OH)2/carbon foam as an efficient electrode for the oxygen evolution reaction.

PubMed

Liu, Zhengqing; Li, Na; Zhao, Hongyang; Zhang, Yi; Huang, Yunhui; Yin, Zongyou; Du, Yaping

2017-04-01

Three dimensional (3D) N, O and S doped carbon foam (NOSCF) is prepared as a substrate for in situ vertically grown Ni(OH) 2 nanosheets. As designed Ni(OH) 2 /NOSCF possesses strong electrostatic interactions with OH - ions due to many C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 O groups existing in NOSCF, which can facilitate the formation of crucial NiOOH intermediates during the OER process. CeO 2 nanoparticles (NPs) of ∼3.3 nm in size are decorated on Ni(OH) 2 nanosheets to design a highly efficient CeO 2 /Ni(OH) 2 /NOSCF electrocatalyst for the oxygen evolution reaction (OER). The CeO 2 NP decorated Ni(OH) 2 /NOSCF not only exhibits a remarkably improved OER performance with an onset potential of 240 mV, outperforming most reported non-noble metal based OER electrocatalysts, but also possesses a small Tafel slope of 57 mV dec -1 and excellent stability under different overpotentials. The synergistic effect of producing more active species of Ni III/IV and accelerating the charge transfer for Ni(OH) 2 /NOSCF by the introduction of CeO 2 NPs is also investigated. These results demonstrate the possibility of designing energy efficient OER catalysts with the assistance of earth abundant CeO 2 -based catalysts.

An Investigation of Faculty Perspectives on Barriers, Incentives, and Benefits of the OER Movement in Turkey

ERIC Educational Resources Information Center

Kursun, Engin; Cagiltay, Kursat; Can, Gulfidan

2014-01-01

The purpose of this survey study is to investigate faculty's perceptions of the main incentives, barriers, and benefits to publishing their course materials for free within the open educational resources (OER) movement. Data were collected from an online survey of 1,637 faculty from 56 universities in Turkey. Results showed that even though the…

Wikiwijs: An Unexpected Journey and the Lessons Learned towards OER

ERIC Educational Resources Information Center

Schuwer, Robert; Kreijns, Karel; Vermeulen, Marjan

2014-01-01

The Dutch Ministry of Education, Culture and Science has funded a five years program to encourage the use, creation and sharing of Open Educational Resources (OER) by teachers from various types of education. This program is known as Wikiwijs. Ultimo 2013, the program has come to an end. As some of the assumptions at the start of Wikiwijs proved…

An Architecture Based on Linked Data Technologies for the Integration and Reuse of OER in MOOCs Context

ERIC Educational Resources Information Center

Piedra, Nelson; Chicaiza, Janneth Alexandra; López, Jorge; Tovar, Edmundo

2014-01-01

The Linked Data initiative is considered as one of the most effective alternatives for creating global shared information spaces, it has become an interesting approach for discovering and enriching open educational resources data, as well as achieving semantic interoperability and re-use between multiple OER repositories. The notion of Linked Data…

Open and Editable: Exploring Library Engagement in Open Educational Resource Adoption, Adaptation and Authoring

ERIC Educational Resources Information Center

Walz, Anita R.

2015-01-01

Open Educational Resources (OER) have saved students millions of dollars in textbook costs and greatly expanded access to a wide variety of educational materials for countless numbers of students and life-long learners. OER have also saved teachers time and effort by allowing them to reuse, modify, and build on materials developed by other…

Defining Openness: Updating the Concept of "Open" for a Connected World

ERIC Educational Resources Information Center

Brent, Isabelle; Gibbs, Graham R.; Gruszczynska, Anna Katarzyna

2012-01-01

The field of Social Research Methods is shared not only by the social sciences, but by many other disciplines. There is therefore enormous scope for the creation and re-use of open educational resources (OERs) in this area. However, our work with social scientists on a number of recent projects suggests that barriers exist to OER creation and use…

A Semantically Enriched Context-Aware OER Recommendation Strategy and Its Application to a Computer Science OER Repository

ERIC Educational Resources Information Center

Ruiz-Iniesta, Almudena; Jiménez-Díaz, Guillermo; Gómez-Albarrán, Mercedes

2014-01-01

This paper describes a knowledge-based strategy for recommending educational resources-worked problems, exercises, quiz questions, and lecture notes-to learners in the first two courses in the introductory sequence of a computer science major (CS1 and CS2). The goal of the recommendation strategy is to provide support for personalized access to…

Knowledge Typologies for Professional Learning: Educators' (Re)Generation of Knowledge When Learning Open Educational Practice

ERIC Educational Resources Information Center

Hood, Nina; Littlejohn, Allison

2017-01-01

Open education resources (OER) and accompanying open education practices (OEP), are changing the education landscape. For educators to take full advantage of the opportunities OER offer they must engage in learning activities to facilitate the extension and adaption of their practice. This paper forms part of a larger study exploring how adult…

School-Based Professional Development in a Developing Context: Lessons Learnt from a Case Study in Zambia

ERIC Educational Resources Information Center

Haßler, Björn; Hennessy, Sara; Cross, Andrew; Chileshe, Eness; Machiko, Brian

2015-01-01

This paper reports on the development and outcomes of the second phase of OER4Schools, a school-based professional development programme supporting interactive forms of subject teaching in conjunction with Open Educational Resources (OER) and technology in Zambian primary schools. We worked with partners to identify the needs of school-based…

User-Oriented Quality for OER: Understanding Teachers' Views on Re-Use, Quality, and Trust

ERIC Educational Resources Information Center

Clements, K. I.; Pawlowski, J. M.

2012-01-01

We analysed how teachers as users of open educational resources (OER) repositories act in the re-use process and how they perceive quality. Based on a quantitative empirical study, we also surveyed which quality requirements users have and how they would contribute to the quality process. Trust in resources, organizations, and technologies seem to…

Towards Development of OER Derived Custom-Built Open Textbooks: A Baseline Survey of University Teachers at the University of the South Pacific

ERIC Educational Resources Information Center

Prasad, Deepak; Usagawa, Tsuyoshi

2014-01-01

Textbook prices have soared over the years, with several studies revealing many university students are finding it difficult to afford textbooks. Fortunately, two innovations--open educational resources (OER) and open textbooks--hold the potential to increase textbook affordability. Experts, though, have stated the obvious: that students can save…

Mainstreaming Open Textbooks: Educator Perspectives on the Impact of OpenStax College Open Textbooks

ERIC Educational Resources Information Center

Pitt, Rebecca

2015-01-01

This paper presents the results of collaborative research between open textbook provider OpenStax College (OSC) and the OER Research Hub (OERRH), a Hewlett funded mixed methods open research project examining the impact of open educational resources (OER) on learning and teaching. The paper focuses primarily on the results of two surveys that were…

Openness and Praxis: Exploring the Use of Open Educational Practices in Higher Education

ERIC Educational Resources Information Center

Cronin, Catherine

2017-01-01

Open educational practices (OEP) is a broad descriptor of practices that include the creation, use, and reuse of open educational resources (OER) as well as open pedagogies and open sharing of teaching practices. As compared with OER, there has been little empirical research on individual educators' use of OEP for teaching in higher education.…

Open Educational Resources for Professionals: A New Era in the Training and Development of Legislative Counsel

ERIC Educational Resources Information Center

Dewhurst, Dale; Keyes, John Mark; Zariski, Archie

2013-01-01

This paper discusses a current project to develop open educational resources (OER) for legislative counsel in countries of the Commonwealth of Nations. The project is the latest step in a 20-year old distance education program for those professionals. The paper explores best practices for investment in freely available OER for use by professionals…

Re-Purposing an OER for the Online Language Course: A Case Study of "Deutsch Interaktiv" by the Deutsche Welle

ERIC Educational Resources Information Center

Dixon, Edward M.; Hondo, Junko

2014-01-01

This paper will describe pedagogical approaches for re-purposing an open educational resource (OER) designed and produced by the Deutsche Welle. This free online program, "Deutsch Interaktiv," consists of authentic digital videos, slideshows and audio texts and gives a contemporary overview of the culture and language in Germany, Austria…

Opening Teaching Landscapes: The Importance of Quality Assurance in the Delivery of Open Educational Resources

ERIC Educational Resources Information Center

Atenas, Javiera; Havemann, Leo; Priego, Ernesto

2014-01-01

Scholars are increasingly being asked to share teaching materials, publish in open access journals, network in social media, and reuse open educational resources (OER). The theoretical benefits of Open Educational Practices (OEP) have become understood in the academic community but thus far, the use of OER has not been rapidly adopted. We aim to…

Evaluating the Effectiveness of the Open-Access ChemWiki Resource as a Replacement for Traditional General Chemistry Textbooks

ERIC Educational Resources Information Center

Allen, Gregory; Guzman-Alvarez, Alberto; Smith, Amy; Gamage, Alan; Molinaro, Marco; Larsen, Delmar S.

2015-01-01

Open educational resources (OERs) provide a potential alternative to costly textbooks and can allow content to be edited and adapted to a variety of classroom environments. At the University of California, Davis, the OER "ChemWiki" project, as part of the greater STEMWiki Hyperlibrary, was developed to supplant traditional post-secondary…

Open Educational Resources for Blended Learning in High Schools: Overcoming Impediments in Developing Countries

ERIC Educational Resources Information Center

Larson, Richard C.; Murray, M. Elizabeth

2008-01-01

With today's computer and telecommunications technologies, every young person can have a quality education regardless of his or her place of birth. This is the dream that Open Educational Resources (OERs), when viewed as a right rather than a privilege, are directed to realize. For developing countries, we propose a type of OER initiative that…

Analytical Insights on the Position, Challenges, and Potential for Promoting OER in ODeL Institutions in Africa

ERIC Educational Resources Information Center

Muganda, Cornelia K.; Samzugi, Athuman S.; Mallinson, Brenda J.

2016-01-01

This paper shares analytical insights on the position, challenges and potential for promoting Open Educational Resources (OER) in African Open Distance and eLearning (ODeL) institutions. The researchers sought to use a participatory research approach as described by Krishnaswamy (2004), in convening a sequence of two workshops at the Open…

OERs in Context--Case Study of Innovation and Sustainability of Educational Practices at the University of Mauritius

ERIC Educational Resources Information Center

Issack, Santally Mohammad

2011-01-01

Over the recent years, there has been a growing interest in Open Educational Resources (OER). A similar trend was observed about a decade ago in the concept of Learning Objects, which inevitably faded without really making an impact in real-world educational contexts. A number of repositories were created that contain thousands of learning…

Collective Designing and Sharing of Open Educational Resources: A Study of the French CARTOUN Platform

ERIC Educational Resources Information Center

Quere, Nolwenn

2017-01-01

Designing and sharing Open Educational Resources (OERs) requires teachers to develop new competences, in particular with digital resources. In this paper, the case of a language resource production group is introduced. Due to the centrality of the OERs in their collective activity, I show that the documents they produce are essential to the…

Emerging Issues: Open Educational Resources--How Science Teachers Can Use Open Educational Resources to Revitalize Lessons

ERIC Educational Resources Information Center

Charles, Karen; Rice, Olivia

2012-01-01

The term "open educational resources" (OERs) was first coined by UNESCO in 2005 and refers to "teaching, learning or research materials that are in the public domain or released with an intellectual property license that allows for free use, adaptation, and/or distribution." OERs offer educators what might be termed "value neutral" online…

CuCo 2O 4 ORR/OER Bi-functional catalyst: Influence of synthetic approach on performance

DOE PAGES

Serov, Alexey; Andersen, Nalin I.; Roy, Aaron J.; ...

2015-02-07

A series of CuCo 2O 4 catalysts were synthesized by pore forming, sol-gel, spray pyrolysis and sacrificial support methods. Catalysts were characterized by XRD, SEM, XPS and BET techniques. The electrochemical activity for the oxygen reduction and oxygen evolution reactions (ORR and OER) was evaluated in alkaline media by RRDE. Density Functional Theory was used to identify two different types of active sites responsible for ORR/OER activity of CuCo 2O 4 and it was found that CuCo 2O 4 can activate the O-O bond by binding molecular oxygen in bridging positions between Co or Co and Cu atoms. It wasmore » found that the sacrificial support method (SSM) catalyst has the highest performance in both ORR and OER and has the highest content of phase-pure CuCo 2O 4. It was shown that the presence of CuO significantly decreases the activity in oxygen reduction and oxygen evolution reactions. As a result, the half-wave potential (E 1/2) of CuCo 2O 4-SSM was found as 0.8 V, making this material a state-of-the-art, unsupported oxide catalyst.« less

Synthetic control and empirical prediction of redox potentials for Co 4O 4 cubanes over a 1.4 V range: implications for catalyst design and evaluation of high-valent intermediates in water oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Andy I.; Wang, Jianing; Levine, Daniel S.

The oxo-cobalt cubane unit [Co 4O 4] is of interest as a homogeneous oxygen-evolution reaction (OER) catalyst, and as a functional mimic of heterogeneous cobalt oxide OER catalysts. The synthesis of several new cubanes allows evaluation of redox potentials for the [Co 4O 4] cluster, which are highly sensitive to the ligand environment and span a remarkable range of 1.42 V. The [Co III 4O 4] 4+/[Co III 3Co IVO 4 ]5+ and [Co III 3Co IVO 4] 5+/[Co III 2Co IV 2O 4] 6+ redox potentials are reliably predicted by the pKas of the ligands. Hydrogen bonding is alsomore » shown to significantly raise the redox potentials, by ~500 mV. The potential-p K a correlation is used to evaluate the feasibility of various proposed OER catalytic intermediates, including high-valent Co-oxo species. The synthetic methods and structure–reactivity relationships developed by these studies should better guide the design of new cubane-based OER catalysts.« less

Ultrafast and large scale preparation of superior catalyst for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Tian, Xianqing; Liu, Yunhua; Xiao, Dan; Sun, Jie

2017-10-01

The development of efficient and earth abundant catalyst for the oxygen evolution reaction (OER) is a key challenge for the renewable energy research community. Here, we report a facile and ultrafast route to immobilize nickel-iron layered double hydroxide (NiFe-LDH) nanoparticles on nickel foam (NF) via soaking the direct electroless deposited prussian blue analogue (PBA) on NF in 1 M KOH. This NiFe-LDH/NF electrode can be prepared in a few seconds without further treatments. It has three-dimensional interpenetrating network originated from its PBA precursor which facilitate the diffusion and ad/desorption of the reactants and producing for OER. And further characterization of the Faradaic efficiency and forced convection tests show direct evidence to demonstrate the formation of free intermediate(s) in the OER process. This electrode (typically NiFe-LDH-20s/NF) exhibits outstanding electrocatalytic activity with low overpotential of ∼0.240 V at 10 mA cm-2, low Tafel slope of 38 mV dec-1, and great stability. This feasible strategy affords a new strategy for the large scale manufacture of low-cost, effective and robust OER electrodes.

Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts

PubMed Central

Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I.; Kuruba, Ramalinga; Damodaran, Krishnan; Jampani, Prashanth; Gattu, Bharat; Shanthi, Pavithra Murugavel; Damle, Sameer S.; Kumta, Prashant N.

2016-01-01

Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu1.5Mn1.5O4, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations. PMID:27380719

Synthetic control and empirical prediction of redox potentials for Co 4O 4 cubanes over a 1.4 V range: implications for catalyst design and evaluation of high-valent intermediates in water oxidation

DOE PAGES

Nguyen, Andy I.; Wang, Jianing; Levine, Daniel S.; ...

2017-04-07

The oxo-cobalt cubane unit [Co 4O 4] is of interest as a homogeneous oxygen-evolution reaction (OER) catalyst, and as a functional mimic of heterogeneous cobalt oxide OER catalysts. The synthesis of several new cubanes allows evaluation of redox potentials for the [Co 4O 4] cluster, which are highly sensitive to the ligand environment and span a remarkable range of 1.42 V. The [Co III 4O 4] 4+/[Co III 3Co IVO 4 ]5+ and [Co III 3Co IVO 4] 5+/[Co III 2Co IV 2O 4] 6+ redox potentials are reliably predicted by the pKas of the ligands. Hydrogen bonding is alsomore » shown to significantly raise the redox potentials, by ~500 mV. The potential-p K a correlation is used to evaluate the feasibility of various proposed OER catalytic intermediates, including high-valent Co-oxo species. The synthetic methods and structure–reactivity relationships developed by these studies should better guide the design of new cubane-based OER catalysts.« less

Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction.

PubMed

Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Zheng, Gengfeng

2015-09-14

A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g(-1), with excellent capacitance retention (>90%) at 10 A g(-1) for over 10,000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm(-2) at 1.65 V vs. the RHE.

Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts

NASA Astrophysics Data System (ADS)

Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I.; Kuruba, Ramalinga; Damodaran, Krishnan; Jampani, Prashanth; Gattu, Bharat; Shanthi, Pavithra Murugavel; Damle, Sameer S.; Kumta, Prashant N.

2016-07-01

Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu1.5Mn1.5O4, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.

Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts.

PubMed

Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I; Kuruba, Ramalinga; Damodaran, Krishnan; Jampani, Prashanth; Gattu, Bharat; Shanthi, Pavithra Murugavel; Damle, Sameer S; Kumta, Prashant N

2016-07-06

Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu1.5Mn1.5O4, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.

Fe3O4@NiSx/rGO composites with amounts of heterointerfaces and enhanced electrocatalytic properties for oxygen evolution

NASA Astrophysics Data System (ADS)

Zhu, Guoxing; Xie, Xulan; Liu, Yuanjun; Li, Xiaoyun; Xu, Keqiang; Shen, Xiaoping; Yao, Yinjie; Shah, Sayyar Ali

2018-06-01

The sluggish oxygen evolution kinetics involved in water splitting and various metal-air batteries makes the effective and inexpensive electrocatalysts be highly desirable for oxygen evolution reaction (OER). Herein, an effective and facile two-step route is developed to construct Fe3O4@NiSx composite loaded on reduced graphene oxide (rGO). The morphology and microstructure of the composites were characterized by different characterization techniques. The obtained composites show amounts of heterointerfaces. The shift of binding energy in X-ray photoelectron spectrum demonstrates the existence of interfacial charge transfer effect between Fe3O4 and NiSx. The optimized Fe3O4@NiSx/rGO sample exhibits excellent electrocatalytic performance toward OER in alkaline media, showing 10 mA·cm-2 at η = 330 mV, lower Tafel slope (35.5 mV·dec-1), and good durability, demonstrating a great perspective. The excellent OER performance can be ascribed to the synergetic effect between Fe and Ni species. It is believed that the heterointerfaces between Fe3O4 and NiSx perform as active centers for OER.

Identification of optimal solar fuel electrocatalysts via high throughput in situ optical measurements

DOE PAGES

Shinde, Aniketa; Guevarra, Dan; Haber, Joel A.; ...

2014-10-21

For many solar fuel generator designs involve illumination of a photoabsorber stack coated with a catalyst for the oxygen evolution reaction (OER). In this design, impinging light must pass through the catalyst layer before reaching the photoabsorber(s), and thus optical transmission is an important function of the OER catalyst layer. Many oxide catalysts, such as those containing elements Ni and Co, form oxide or oxyhydroxide phases in alkaline solution at operational potentials that differ from the phases observed in ambient conditions. To characterize the transparency of such catalysts during OER operation, 1031 unique compositions containing the elements Ni, Co, Ce,more » La, and Fe were prepared by a high throughput inkjet printing technique. Moreover, the catalytic current of each composition was recorded at an OER overpotential of 0.33 V with simultaneous measurement of the spectral transmission. By combining the optical and catalytic properties, the combined catalyst efficiency was calculated to identify the optimal catalysts for solar fuel applications within the material library. Our measurements required development of a new high throughput instrument with integrated electrochemistry and spectroscopy measurements, which enables various spectroelectrochemistry experiments.« less

Free-standing ternary NiWP film for efficient water oxidation reaction

NASA Astrophysics Data System (ADS)

Yang, Yunpeng; Zhou, Kuo; Ma, Lili; Liang, Yanqin; Yang, Xianjin; Cui, Zhenduo; Zhu, Shengli; Li, Zhaoyang

2018-03-01

High-efficient catalysts for oxygen evolution reaction (OER) is of great concern in improving energy efficiency for water splitting. Here we report a high-performance OER electrocatalyst of nickel-tungsten-phosphorus (NiWP) film prepared by template method. This free-standing ternary electrocatalyst exhibits a remarkable electrocatalytic activity of OER in alkaline medium due to the synergetic effect among these elements and the good electrical conductivity. The reported NiWP composite catalyst has an overpotential of as low as 0.4 V (vs. RHE) at 30 mA cm-2, better than that of the commercial RuO2 catalyst. Moreover, a small charge transfer resistance of 4.06 Ω and a Tafel slope of 68 mV dec-1 demonstrate the outstanding catalytic activity.

Reducing Iridium Loading in Oxygen Evolution Reaction Electrocatalysts Using Core–Shell Particles with Nitride Cores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tackett, Brian M.; Sheng, Wenchao; Kattel, Shyam

Here, the oxygen evolution reaction (OER) has broad applications in electrochemical devices, but it often requires expensive and scarce Ir-based catalysts in acid electrolyte. Presented here is a framework to reduce Ir loading by combining core–shell iridium/metal nitride morphologies using in situ experiments and density functional theory (DFT) calculations. Several group VIII transition metal (Fe, Co, and Ni) nitrides are studied as core materials, with Ir/Fe 4N core–shell particles showing enhancement in both OER activity and stability. In situ X-ray absorption fine structure measurements are used to determine the structure and stability of the core–shell catalysts under OER conditions. DFTmore » calculations are used to demonstrate adsorbate binding energies as descriptors of the observed activity trends.« less

Transition Metal Oxides as Electrocatalysts for the Oxygen Evolution Reaction in Alkaline Solutions: An Application-Inspired Renaissance.

PubMed

Song, Fang; Bai, Lichen; Moysiadou, Aliki; Lee, Seunghwa; Hu, Chao; Liardet, Laurent; Hu, Xile

2018-06-27

Water splitting is the essential chemical reaction to enable the storage of intermittent energies such as solar and wind in the form of hydrogen fuel. The oxygen evolution reaction (OER) is often considered as the bottleneck in water splitting. Though metal oxides had been reported as OER electrocatalysts more than half a century ago, the recent interest in renewable energy storage has spurred a renaissance of the studies of transition metal oxides as Earth-abundant and nonprecious OER catalysts. This Perspective presents major progress in several key areas of the field such as theoretical understanding, activity trend, in situ and operando characterization, active site determination, and novel materials. A personal overview of the past achievements and future challenges is also provided.

Reducing Iridium Loading in Oxygen Evolution Reaction Electrocatalysts Using Core–Shell Particles with Nitride Cores

DOE PAGES

Tackett, Brian M.; Sheng, Wenchao; Kattel, Shyam; ...

2018-02-16

Here, the oxygen evolution reaction (OER) has broad applications in electrochemical devices, but it often requires expensive and scarce Ir-based catalysts in acid electrolyte. Presented here is a framework to reduce Ir loading by combining core–shell iridium/metal nitride morphologies using in situ experiments and density functional theory (DFT) calculations. Several group VIII transition metal (Fe, Co, and Ni) nitrides are studied as core materials, with Ir/Fe 4N core–shell particles showing enhancement in both OER activity and stability. In situ X-ray absorption fine structure measurements are used to determine the structure and stability of the core–shell catalysts under OER conditions. DFTmore » calculations are used to demonstrate adsorbate binding energies as descriptors of the observed activity trends.« less

The Role of Postgraduate Students in Co-Authoring Open Educational Resources to Promote Social Inclusion: A Case Study at the University of Cape Town

ERIC Educational Resources Information Center

Hodgkinson-Williams, Cheryl; Paskevicius, Michael

2012-01-01

Like many universities worldwide, the University of Cape Town (UCT) in South Africa has joined the open educational resources (OER) movement, making a selection of teaching and learning materials available through its OER directory, UCT OpenContent. However, persuading and then supporting busy academics to share their teaching materials as OER…

Tracking the Money for Open Educational Resources in South African Basic Education: What We Don't Know

ERIC Educational Resources Information Center

Goodier, Sarah

2017-01-01

Limited research has been done to date on the extent of public funding of Open Educational Resources (OER) within basic education (K-12 equivalent) in South Africa. As claims have been made about the potential cost reductions that come with using OER, this study aimed to establish a benchmark of public spending on educational resources, uncover…

Special Report on the Role of Open Educational Resources in Supporting the Sustainable Development Goal 4: Quality Education Challenges and Opportunities

ERIC Educational Resources Information Center

McGreal, Rory

2017-01-01

Open Educational Resources (OER) and their offspring, Massive Open Online Courses (MOOCs), are becoming important factors in achieving the "Sustainable Development Goal 4: Quality Education" ("SDG4"). The OER movement is less than 15 years old and is growing rapidly as more and more nations and institutions adopt the view that…

Mass Customization of Education by an Institution of HE: What Can We Learn from Industry?

ERIC Educational Resources Information Center

Schuwer, Robert; Kusters, Rob

2014-01-01

One of the claims the OER movement makes is that availability of (open) digital learning materials improves the quality of education. The promise is the ability to offer educational programs that take into account specific demands of the learner. The question is how to reach a situation where a customized demand can be met using OER with…

The United States Air Force Officer Effectiveness Report as Promotion Selection Tool

DTIC Science & Technology

1986-03-01

Force <USAF) Officer Effectiveness Report (OER) is the performance appraisal system for the officer corps. Uses of the ÜBR include r personnel...studies in performance appraisal; discusses the extent to which the present OER addresses leadership; and, makes recommendations for improving the... performance factors. T’iese traits are: knowledge, planning ability, goal setting, communicative ability, personal contacts, initiative, delegation, and

Herzberg, Hygiene and the Motivation to Reuse: Towards a Three-Factor Theory to Explain Motivation to Share and Use OER

ERIC Educational Resources Information Center

Pegler, Chris

2012-01-01

The list of barriers and enablers that influence the use of open educational resources (OER) is extensive. Factors and influences relating to reuse may have been noted within projects, operating within a short time span, or within specific conditions which limit generalizability. Evidence of reuse in practice has often emerged as isolated examples…

Spot Scanning and Passive Scattering Proton Therapy: Relative Biological Effectiveness and Oxygen Enhancement Ratio in Cultured Cells.

PubMed

Iwata, Hiromitsu; Ogino, Hiroyuki; Hashimoto, Shingo; Yamada, Maho; Shibata, Hiroki; Yasui, Keisuke; Toshito, Toshiyuki; Omachi, Chihiro; Tatekawa, Kotoha; Manabe, Yoshihiko; Mizoe, Jun-etsu; Shibamoto, Yuta

2016-05-01

To determine the relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and contribution of the indirect effect of spot scanning proton beams, passive scattering proton beams, or both in cultured cells in comparison with clinically used photons. The RBE of passive scattering proton beams at the center of the spread-out Bragg peak (SOBP) was determined from dose-survival curves in 4 cell lines using 6-MV X rays as controls. Survival of 2 cell lines after spot scanning and passive scattering proton irradiation was then compared. Biological effects at the distal end region of the SOBP were also investigated. The OER of passive scattering proton beams and 6 MX X rays were investigated in 2 cell lines. The RBE and OER values were estimated at a 10% cell survival level. The maximum degree of protection of radiation effects by dimethyl sulfoxide was determined to estimate the contribution of the indirect effect against DNA damage. All experiments comparing protons and X rays were made under the same biological conditions. The RBE values of passive scattering proton beams in the 4 cell lines examined were 1.01 to 1.22 (average, 1.14) and were almost identical to those of spot scanning beams. Biological effects increased at the distal end of the SOBP. In the 2 cell lines examined, the OER was 2.74 (95% confidence interval, 2.56-2.80) and 3.08 (2.84-3.11), respectively, for X rays, and 2.39 (2.38-2.43) and 2.72 (2.69-2.75), respectively, for protons (P<.05 for both cells between X rays and protons). The maximum degree of protection was significantly higher for X rays than for proton beams (P<.05). The RBE values of spot scanning and passive scattering proton beams were almost identical. The OER was lower for protons than for X rays. The lower contribution of the indirect effect may partly account for the lower OER of protons. Copyright © 2016 Elsevier Inc. All rights reserved.

Structure Effects of 2D Materials on α-Nickel Hydroxide for Oxygen Evolution Reaction.

PubMed

Luan, Chenglong; Liu, Guangli; Liu, Yujie; Yu, Lei; Wang, Yao; Xiao, Yun; Qiao, Hongyan; Dai, Xiaoping; Zhang, Xin

2018-04-24

To engineer low-cost, high-efficiency, and stable oxygen evolution reaction (OER) catalysts, structure effects should be primarily understood. Focusing on this, we systematically investigated the relationship between structures of materials and their OER performances by taking four 2D α-Ni(OH) 2 as model materials, including layer-stacked bud-like Ni(OH) 2 -NB, flower-like Ni(OH) 2 -NF, and petal-like Ni(OH) 2 -NP as well as the ultralarge sheet-like Ni(OH) 2 -NS. For the first three (layer-stacking) catalysts, with the decrease of stacked layers, their accessible surface areas, abilities to adsorb OH - , diffusion properties, and the intrinsic activities of active sites increase, which accounts for their steadily enhanced activity. As expected, Ni(OH) 2 -NP shows the lowest overpotential (260 mV at 10 mA cm -2 ) and Tafel slope (78.6 mV dec -1 ) with a robust stability over 10 h among the samples, which also outperforms the benchmark IrO 2 (360 mV and 115.8 mV dec -1 ) catalyst. Interestingly, Ni(OH) 2 -NS relative to Ni(OH) 2 -NP exhibits even faster substance diffusion due to the sheet-like structure, but shows inferior OER activity, which is mainly because the Ni(OH) 2 -NP with a smaller size possesses more active boundary sites (higher reactivity of active sites) than Ni(OH) 2 -NS, considering the adsorption properties and accessible surface areas of the two samples are quite similar. By comparing the different structures and their OER behaviors of four α-Ni(OH) 2 samples, our work may shed some light on the structure effect of 2D materials and accelerate the development of efficient OER catalysts.

Controlling the Interfacial Environment in the Electrosynthesis of MnOx Nanostructures for High-Performance Oxygen Reduction/Evolution Electrocatalysis.

PubMed

Hosseini-Benhangi, Pooya; Kung, Chun Haow; Alfantazi, Akram; Gyenge, Elöd L

2017-08-16

High-performance, nonprecious metal bifunctional electrocatalysts for the oxygen reduction and evolution reactions (ORR and OER, respectively) are of great importance for rechargeable metal-air batteries and regenerative fuel cells. A comprehensive study based on statistical design of experiments is presented to investigate and optimize the surfactant-assisted structure and the resultant bifunctional ORR/OER activity of anodically deposited manganese oxide (MnO x ) catalysts. Three classes of surfactants are studied: anionic (sodium dodecyl sulfate, SDS), non-ionic (t-octylphenoxypolyethoxyethanol, Triton X-100), and cationic (cetyltrimethylammonium bromide, CTAB). The adsorption of surfactants has two main effects: increased deposition current density due to higher Mn 2+ and Mn 3+ concentrations at the outer Helmholtz plane (Frumkin effect on the electrodeposition kinetics) and templating of the MnO x nanostructure. CTAB produces MnO x with nanoneedle (1D) morphology, whereas nanospherical- and nanopetal-like morphologies are obtained with SDS and Triton, respectively. The bifunctional performance is assessed based on three criteria: OER/ORR onset potential window (defined at 2 and -2 mA cm -2 ) and separately the ORR and OER mass activities. The best compromise among these three criteria is obtained either with Triton X-100 deposited catalyst composed of MnOOH and Mn 3 O 4 or SDS deposited catalyst containing a combination of α- and β-MnO 2 , MnOOH, and Mn 3 O 4 .The interaction effects among the deposition variables (surfactant type and concentration, anode potential, Mn 2+ concentration, and temperature) reveal the optimal strategy for high-activity bifunctional MnO x catalyst synthesis. Mass activities for OER and ORR up to 49 A g -1 (at 1556 mV RHE ) and -1.36 A g -1 (at 656 mV RHE ) are obtained, respectively.

In situ evolution of highly dispersed amorphous CoO x clusters for oxygen evolution reaction

DOE PAGES

Chen, Dawei; Dong, Chung-Li; Zou, Yuqin; ...

2017-07-24

Electrocatalytic water splitting is a key technique to produce hydrogen fuels, which can be considered as an efficient strategy to store renewable energy. Oxygen evolution reaction (OER) that occurs at the anode side requires a four-electron transfer under highly oxidizing conditions. OER has a large overpotential and therefore determines the overall efficiency. Certain electrocatalysts can efficiently help to improve the reaction kinetics. Owing to the high cost of precious metals such as Pt, Ru, and Ir, non-precious metal oxide catalysts have been vigorously investigated under alkaline conditions. Herein, we synthesized novel highly dispersed amorphous CoO x for the first timemore » in the form of a cluster favorable to enhance the OER activity using a facile method via the air dielectric barrier discharge (DBD) plasma. Compared with the pristine biopolymer–cobalt complex, the amorphous CoO x cluster exhibits a much higher current density and a lower overpotential for OER, e.g., the overpotential of 290 mV at 10 mA cm -2 and the overpotential of only 350 mV at 300 mA cm -1. The excellent electrocatalytic OER activity was attributed to the unsaturated catalytic sites on the amorphous CoO x cluster. In addition, we studied the reaction mechanism, and it was observed that pure O 2 DBD plasma could lead to the evolution of crystalline CoO x; however, the presence of N 2 and O 2 in DBD plasma could ensure the facile evolution of amorphous CoO x clusters. This study provides a new strategy, therefore, to design amorphous materials for electrocatalysis and beyond.« less

In situ evolution of highly dispersed amorphous CoO x clusters for oxygen evolution reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dawei; Dong, Chung-Li; Zou, Yuqin

Electrocatalytic water splitting is a key technique to produce hydrogen fuels, which can be considered as an efficient strategy to store renewable energy. Oxygen evolution reaction (OER) that occurs at the anode side requires a four-electron transfer under highly oxidizing conditions. OER has a large overpotential and therefore determines the overall efficiency. Certain electrocatalysts can efficiently help to improve the reaction kinetics. Owing to the high cost of precious metals such as Pt, Ru, and Ir, non-precious metal oxide catalysts have been vigorously investigated under alkaline conditions. Herein, we synthesized novel highly dispersed amorphous CoO x for the first timemore » in the form of a cluster favorable to enhance the OER activity using a facile method via the air dielectric barrier discharge (DBD) plasma. Compared with the pristine biopolymer–cobalt complex, the amorphous CoO x cluster exhibits a much higher current density and a lower overpotential for OER, e.g., the overpotential of 290 mV at 10 mA cm -2 and the overpotential of only 350 mV at 300 mA cm -1. The excellent electrocatalytic OER activity was attributed to the unsaturated catalytic sites on the amorphous CoO x cluster. In addition, we studied the reaction mechanism, and it was observed that pure O 2 DBD plasma could lead to the evolution of crystalline CoO x; however, the presence of N 2 and O 2 in DBD plasma could ensure the facile evolution of amorphous CoO x clusters. This study provides a new strategy, therefore, to design amorphous materials for electrocatalysis and beyond.« less

Free-standing, flexible β-Ni(OH)2/electrochemically-exfoliated graphene film electrode for efficient oxygen evolution

NASA Astrophysics Data System (ADS)

Wang, Lanlan; Zhang, Jian; Jiang, Weitao; Zhao, Hong; Liu, Hongzhong

2018-03-01

The oxidation of water into molecular oxygen (oxygen evolution reaction, OER) is a pivotal reaction in many energy conversion devices. The high cost of IrO2, however, seriously hinder its large-scale applications in water oxidation. Here, we have at first reported a free-standing and flexible film electrode consisting of 2D β-Ni(OH)2/electrochemically-exfoliated graphene hybrid nanosheets (NiG-2), which is synthesized by a solvothermal reaction and an assembly process. The as-obtained NiG-2 film electrode exhibited an excellent electrocatalytic OER activity with an extremely low OER onset overpotential of ∼250 mV in a 1 M KOH aqueous solution, which is lower than these of the commercial Ir/C (370 mV at 10 mA cm-2) catalyst.

The Realities of "Reaching Out": Enacting the Public-Facing Open Scholar Role with Existing Online Communities

ERIC Educational Resources Information Center

Perryman, Leigh-Anne; Coughlan, Tony

2013-01-01

A core tenet of the open educational resources (OER) movement has long been that 'the world's knowledge is a public good' (Smith & Casserly, 2006, p.2) and should be available for everyone to use, reuse and share. However, this vision of openness and of the connection between OER and social justice, which McAndrew and Farrow…

How Korean Language Arts Teachers Adopt and Adapt Open Educational Resources: A Study of Teachers' and Students' Perspectives

ERIC Educational Resources Information Center

Kwak, SuBeom

2017-01-01

Since 2005, open educational resources (OER) have played a key role in K-12 education in South Korea; so far, however, there has been little discussion about OER efficacy in South Korean K-12 education. In the meantime, South Korean education has been attracting a lot of interest around the world. Former U.S. President Obama's comments about South…

Analysis of PLEs' Implementation under OER Design as a Productive Teaching-Learning Strategy in Higher Education. A Case Study at Universidad Nacional de Educación a Distancia

ERIC Educational Resources Information Center

Vázquez-Cano, Esteban; Martín-Monje, Elena; Castrillo de Larreta-Azelain, María Dolores

2016-01-01

This paper shows some research which analysed the didactic functionality of Personal Learning Environments (PLEs) and Open Educational Resources (OERs). They were created by students from the Master's Degree in Information and Communication Technologies applied to language teaching and processing, at Universidad Nacional de Educación a Distancia…

Open Educational Practices and Attitudes to Openness across India: Reporting the Findings of the Open Education Research Hub Pan-India Survey

ERIC Educational Resources Information Center

Perryman, Leigh-Anne; Seal, Tim

2016-01-01

In recent years India has shown a growing appetite for open educational resources (OER) and open educational practices (OEP). Despite this, there is a paucity of research on OER use and impact, the extensiveness of OEP, and attitudes towards openness in India. This paper reports on research intended to help fill that knowledge gap by conducting a…

Perovskite/Carbon Composites: Applications in Oxygen Electrocatalysis.

PubMed

Zhu, Yinlong; Zhou, Wei; Shao, Zongping

2017-03-01

Oxygen electrocatalysis, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), plays an extremely important role in oxygen-based renewable-energy technologies such as rechargeable metal-air batteries, regenerative fuel cells and water splitting. Perovskite oxides have recently attracted increasing interest and hold great promise as efficient ORR and OER catalysts to replace noble-metal-based catalysts, owing to their high intrinsic catalytic activity, abundant variety, low cost, and rich resources. The introduction of perovskite-carbon interfaces by forming perovskite/carbon composites may bring a synergistic effect between the two phases, thus benefiting the oxygen electrocatalysis. This review provides a comprehensive overview of recent advances in perovskite/carbon composites for oxygen electrocatalysis in alkaline media, aiming to provide insights into the key parameters that influence the ORR/OER performance of the composites, including the physical/chemical properties and morphologies of the perovskites, the multiple roles of carbon, the synthetic method and the synergistic effect. A special emphasis is placed on the origin of the synergistic effect associated with the interfacial interaction between the perovskite and the carbon phases for enhanced ORR/OER performance. Finally, the existing challenges and the future directions for the synthesis and development of more efficient oxygen catalysts based on perovskite/carbon composites are proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafine and highly disordered Ni 2 Fe 1 nanofoams enabled highly efficient oxygen evolution reaction in alkaline electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Shaofang; Song, Junhua; Zhu, Chengzhou

Nickel iron hydroxides are the most promising non-noble electrocatalysts for oxygen evolution reaction (OER) in alkaline media. By in situ reduction of metal precursors, compositionally controlled three-dimensional (3D) NixFeyB nanofoams (NFs) are synthesized with high surface area and uniformly distributed bimetallic networks. The resultant ultrafine amorphous Ni2Fe1B NFs exhibit extraordinary electrocatalytic performance toward OER and overall water splitting in alkaline media. At a potential as low as 1.42 V (vs. RHE), Ni2Fe1B NFs can deliver a current density of 10 mA/cm2 and show negligible activity loss after 12 hours’ stability test. Even at large current flux of 100 mA/cm2, anmore » ultralow overpotential of 0.27 V is achieved, which is about 0.18 V more negative than benchmark RuO2. Both ex-situ Mӧssbauer spectroscopy and X-ray Absorption Spectroscopy (XAS) reveal a phase separation and transformation for the Ni2Fe1B catalyst during OER process. The evolution of oxidation state and disordered structure of Ni2Fe1B might be a key to the high catalytic performance for OER.« less

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Lei; Luo, Langli; Feng, Zhenxing

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhanced reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and poor durability. Here, we report OER catalysts of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells derived from bimetallic metal–organic frameworks (MOFs) precursors. The optimal OER catalyst shows excellent activity (360 mV overpotential atmore » 10 mA cm–2GEO) and durability (no obvious degradation after 20 000 cycles). The electron-donation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by chemical state of precursors. Severe metal particle growth probably caused by oxidation of carbon shells and encapsulated nanoparticles is believed to the main mechanism for activity degradation in these catalysts.« less

Oxygen evolution reaction catalysis

DOEpatents

Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

2016-09-06

An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

Asymmetric 3d Electronic Structure for Enhanced Oxygen Evolution Catalysis.

PubMed

Liu, Yang; Yin, Shibin; Shen, Pei Kang

2018-06-27

The oxygen evolution reaction (OER) is an essential process for renewable energy, and designing a bifunctional oxygen electrocatalyst with high catalytic performance plays a significant role. In this work, FeS, Ni 3 S 2 , Fe 5 Ni 4 S 8 , and N, O, S-doped meshy carbon base were successfully synthesized. The sample containing Fe 5 Ni 4 S 8 exhibited excellent OER performance. The density functional theory calculations indicate that the partial density of states for 3d electrons (3d-PDOS) of Fe and Ni atoms are changed from monometallic sulfide to bimetallic sulfide at the sulfur vacancy. The asymmetric 3d electronic structure optimizes the 3d-PDOS of Fe and Ni atoms, and leads to an enhanced OER activity. This work provides a new strategy to prepare a low-cost electrocatalyst for oxygen evolution with high-efficiency.

Homogeneously dispersed, multimetal oxygen-evolving catalysts

DOE PAGES

Zhang, Bo; Zheng, Xueli; Voznyy, Oleksandr; ...

2016-03-24

Earth-abundant first-row (3d) transition-metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials significantly above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxy-hydroxide materials with an atomically homogeneous metal distribution. These gelled FeCoW oxy-hydroxide exhibits the lowest overpotential (191 mV) reported at 10 mA per square centimeter in alkaline electrolyte. Here, the catalyst shows no evidence of degradation following more than 500 hours of operation. X-ray absorption and computationalmore » studies reveal a synergistic interplay between W, Fe and Co in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER.« less

The mechanisms of oxygen reduction and evolution reactions in nonaqueous lithium-oxygen batteries.

PubMed

Cao, Ruiguo; Walter, Eric D; Xu, Wu; Nasybulin, Eduard N; Bhattacharya, Priyanka; Bowden, Mark E; Engelhard, Mark H; Zhang, Ji-Guang

2014-09-01

A fundamental understanding of the mechanisms of both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in nonaqueous lithium-oxygen (Li-O2) batteries is essential for the further development of these batteries. In this work, we systematically investigate the mechanisms of the ORR/OER reactions in nonaqueous Li-O2 batteries by using electron paramagnetic resonance (EPR) spectroscopy, using 5,5-dimethyl-pyrroline N-oxide as a spin trap. The study provides direct verification of the formation of the superoxide radical anion (O2(˙-)) as an intermediate in the ORR during the discharge process, while no O2(˙-) was detected in the OER during the charge process. These findings provide insight into, and an understanding of, the fundamental reaction mechanisms involving oxygen and guide the further development of this field. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photochemical route for accessing amorphous metal oxide materials for water oxidation catalysis.

PubMed

Smith, Rodney D L; Prévot, Mathieu S; Fagan, Randal D; Zhang, Zhipan; Sedach, Pavel A; Siu, Man Kit Jack; Trudel, Simon; Berlinguette, Curtis P

2013-04-05

Large-scale electrolysis of water for hydrogen generation requires better catalysts to lower the kinetic barriers associated with the oxygen evolution reaction (OER). Although most OER catalysts are based on crystalline mixed-metal oxides, high activities can also be achieved with amorphous phases. Methods for producing amorphous materials, however, are not typically amenable to mixed-metal compositions. We demonstrate that a low-temperature process, photochemical metal-organic deposition, can produce amorphous (mixed) metal oxide films for OER catalysis. The films contain a homogeneous distribution of metals with compositions that can be accurately controlled. The catalytic properties of amorphous iron oxide prepared with this technique are superior to those of hematite, whereas the catalytic properties of a-Fe(100-y-z)Co(y)Ni(z)O(x) are comparable to those of noble metal oxide catalysts currently used in commercial electrolyzers.

Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

NASA Astrophysics Data System (ADS)

Qi, Chunling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhao, Aihua; Jia, Dianzeng

2018-01-01

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co3O4/NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co3O4/NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co3O4 nanoparticles and nitrogen doped carbon structures.

Brownmillerite-type Ca2 FeCoO5 as a Practicable Oxygen Evolution Reaction Catalyst.

PubMed

Tsuji, Etsushi; Motohashi, Teruki; Noda, Hiroyuki; Kowalski, Damian; Aoki, Yoshitaka; Tanida, Hajime; Niikura, Junji; Koyama, Yukinori; Mori, Masahiro; Arai, Hajime; Ioroi, Tsutomu; Fujiwara, Naoko; Uchimoto, Yoshiharu; Ogumi, Zempachi; Habazaki, Hiroki

2017-07-21

Here, we report remarkable oxygen evolution reaction (OER) catalytic activity of brownmillerite (BM)-type Ca 2 FeCoO 5 . The OER activity of this oxide is comparable to or beyond those of the state-of-the-art perovskite (PV)-catalyst Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) and a precious-metal catalyst RuO 2 , emphasizing the importance of the characteristic BM structure with multiple coordination environments of transition metal (TM) species. Also, Ca 2 FeCoO 5 is clearly advantageous in terms of expense/laboriousness of the material synthesis. These facts make this oxide a promising OER catalyst used in many energy conversion technologies such as metal-air secondary batteries and hydrogen production from electrochemical/photocatalytic water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Homogeneously dispersed multimetal oxygen-evolving catalysts.

PubMed

Zhang, Bo; Zheng, Xueli; Voznyy, Oleksandr; Comin, Riccardo; Bajdich, Michal; García-Melchor, Max; Han, Lili; Xu, Jixian; Liu, Min; Zheng, Lirong; García de Arquer, F Pelayo; Dinh, Cao Thang; Fan, Fengjia; Yuan, Mingjian; Yassitepe, Emre; Chen, Ning; Regier, Tom; Liu, Pengfei; Li, Yuhang; De Luna, Phil; Janmohamed, Alyf; Xin, Huolin L; Yang, Huagui; Vojvodic, Aleksandra; Sargent, Edward H

2016-04-15

Earth-abundant first-row (3d) transition metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials substantially above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxyhydroxides materials with an atomically homogeneous metal distribution. These gelled FeCoW oxyhydroxides exhibit the lowest overpotential (191 millivolts) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation after more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between tungsten, iron, and cobalt in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER. Copyright © 2016, American Association for the Advancement of Science.

Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application

NASA Astrophysics Data System (ADS)

Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

2017-03-01

Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co0.54Fe0.46OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co0.54Fe0.46OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application.

Oxygen Vacancy Engineering of Co3 O4 Nanocrystals through Coupling with Metal Support for Water Oxidation.

PubMed

Zhang, Jun-Jun; Wang, Hong-Hui; Zhao, Tian-Jian; Zhang, Ke-Xin; Wei, Xiao; Jiang, Zhi-Dong; Hirano, Shin-Ichi; Li, Xin-Hao; Chen, Jie-Sheng

2017-07-21

Oxygen vacancies can help to capture oxygen-containing species and act as active centers for oxygen evolution reaction (OER). Unfortunately, effective methods for generating a high amount of oxygen vacancies on the surface of various nanocatalysts are rather limited. Here, we described an effective way to generate oxygen-vacancy-rich surface of transition metal oxides, exemplified with Co 3 O 4 , simply by constructing highly coupled interface of ultrafine Co 3 O 4 nanocrystals and metallic Ti. Impressively, the amounts of oxygen vacancy on the surface of Co 3 O 4 /Ti surpassed the reported values of the Co 3 O 4 modified even under highly critical conditions. The Co 3 O 4 /Ti electrode could provide a current density of 23 mA cm -2 at an OER overpotential of 570 mV, low Tafel slope, and excellent durability in neutral medium. Because of the formation of a large amount of oxygen vacancies as the active centers for OER on the surface, the TOF value of the Co 3 O 4 @Ti electrode was optimized to be 3238 h -1 at an OER overpotential of 570 mV, which is 380 times that of the state-of-the-art non-noble nanocatalysts in the literature. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application.

PubMed

Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

2017-03-08

Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co 0.54 Fe 0.46 OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co 0.54 Fe 0.46 OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application.

3D structured Mo-doped Ni3S2 nanosheets as efficient dual-electrocatalyst for overall water splitting

NASA Astrophysics Data System (ADS)

Wu, Chengrong; Liu, Bitao; Wang, Jun; Su, Yongyao; Yan, Hengqing; Ng, Chuntan; Li, Cheng; Wei, Jumeng

2018-05-01

Searching for a cost-effective, high efficient and stable bifunctional electrocatalyst for overall water-splitting is critical to renewable energy systems. In this study, three-dimensional (3D) curved nanosheets of Mo-doped Ni3S2 grown on nickel foam were successfully synthesized via a one-step hydrothermal process. The hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) in alkaline environment of this 3D catalyst are investigated in detail. The results show that it possesses lower overpotential, high current densities and small Tafel slopes both in OER and HER. For HER, the catalysts show excellent electrochemical performance, demonstrating a low over-potential of 212 mV at 10 mA cm-2 with a large decrease of 127 mV compared to the undoped Ni3S2. And it also shows a lower overpotential of 260 mV at 10 mA cm-2 which decreases 30 mV for OER. In addition, it is only need 1.67 V for the overall water splitting at 10 mA cm-2 which is 70 mV. It found that the Mo element would change the morphology of Ni3S2 and induce much more active sites for HER and OER. The as-prepared Mo-doped Ni3S2 bi-functional electrocatalyst could act as the promising electrode materials for water splitting.

Ce-Doped NiFe-Layered Double Hydroxide Ultrathin Nanosheets/Nanocarbon Hierarchical Nanocomposite as an Efficient Oxygen Evolution Catalyst.

PubMed

Xu, Huajie; Wang, Bingkai; Shan, Changfu; Xi, Pinxian; Liu, Weisheng; Tang, Yu

2018-02-21

Developing convenient doping to build highly active oxygen evolution reaction (OER) electrocatalysts is a practical process for solving the energy crisis. Herein, a facile and low-cost in situ self-assembly strategy for preparing a Ce-doped NiFe-LDH nanosheets/nanocarbon (denoted as NiFeCe-LDH/CNT, LDH = layered double hydroxide and CNT = carbon nanotube) hierarchical nanocomposite is established for enhanced OER, in which the novel material provides its overall advantageous structural features, including high intrinsic catalytic activity, rich redox properties, high, flexible coordination number of Ce 3+ , and strongly coupled interface. Further experimental results indicate that doped Ce into NiFe-LDH/CNT nanoarrays brings about the reinforced specific surface area, electrochemical surface area, lattice defects, and the electron transport between the LDH nanolayered structure and the framework of CNTs. The effective synergy prompts the NiFeCe-LDH/CNT nanocomposite to possess superior OER electrocatalytic activity with a low onset potential (227 mV) and Tafel slope (33 mV dec -1 ), better than the most non-noble metal-based OER electrocatalysts reported. Therefore, the combination of the remarkable catalytic ability and the facile normal temperature synthesis conditions endows the Ce-doped LDH nanocomposite as a promising catalyst to expand the field of lanthanide-doped layered materials for efficient water-splitting electrocatalysis with scale-up potential.

Impact of IrRu Oxygen Evolution Reaction Catalysts on Pt Nanostructured Thin Films under Start-Up/Shutdown Cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, David A; More, Karren Leslie; Atanasoska, Liliana

Electron microscopy and X-ray photoelectron spectroscopy (XPS) methods have been utilized to study the role of oxygen evolution reaction (OER) catalysts in mitigating degradation arising from start-up/shutdown events. Pt nanostructured thin films (NSTF) were coated with a Ru0.1Ir0.9 OER catalyst at loadings ranging from 1 to 10 g/cm2 and submitted to 5,000 potential cycles within a membrane electrode assembly. Analysis of the as-deposited catalyst showed that Ir and Ru coating is primarily metallic, and further evidence is provided to support the previously reported interaction between Ru and the perylene-red support. Aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopymore » were used to observe the impact of the OER catalysts on Pt dissolution and migration through the membrane. Elemental mapping showed a high percentage of the Ir catalyst was maintained on the NSTF whisker surfaces following testing. The presence of the OER catalysts greatly reduced the smoothing of the Pt NSTF whiskers, which has been correlated with Pt dissolution and losses in electrochemically active surface area. The dissolution of both Ir and Pt led to the formation of IrPt nanoparticle clusters in the membrane close to the cathode, as well as the formation of a Pt band deeper in the membrane.« less

Tumour control in ion beam radiotherapy with different ions in the presence of hypoxia: an oxygen enhancement ratio model based on the microdosimetric kinetic model

NASA Astrophysics Data System (ADS)

Strigari, L.; Torriani, F.; Manganaro, L.; Inaniwa, T.; Dalmasso, F.; Cirio, R.; Attili, A.

2018-03-01

Few attempts have been made to include the oxygen enhancement ratio (OER) in treatment planning for ion beam therapy, and systematic studies to evaluate the impact of hypoxia in treatment with the beam of different ion species are sorely needed. The radiobiological models used to quantify the OER in such studies are mainly based on the dose-averaged LET estimates, and do not explicitly distinguish between the ion species and fractionation schemes. In this study, a new type of OER modelling, based on the microdosimetric kinetic model, taking into account the specificity of the different ions, LET spectra, tissues and fractionation schemes, has been developed. The model has been benchmarked with published in vitro data, HSG, V79 and CHO cells in aerobic and hypoxic conditions, for different ion irradiation. The model has been included in the simulation of treatments for a clinical case (brain tumour) using proton, lithium, helium, carbon and oxygen ion beams. A study of the tumour control probability (TCP) as a function of oxygen partial pressure, dose per fraction and primary ion type has been performed. The modelled OER depends on both the LET and ion type, also showing a decrease for an increased dose per fraction with a slope that depends on the LET and ion type, in good agreement with the experimental data. In the investigated clinical case, a significant increase in TCP has been found upon increasing the ion charge. Higher OER variations as a function of dose per fraction have also been found for low-LET ions (up to 15% varying from 2 to 8 Gy(RBE) for protons). This model could be exploited in the identification of treatment condition optimality in the presence of hypoxia, including fractionation and primary particle selection.

Derivation of Two Critical Appraisal Scores for Trainees to Evaluate Online Educational Resources: A METRIQ Study

PubMed Central

Chan, Teresa M.; Thoma, Brent; Krishnan, Keeth; Lin, Michelle; Carpenter, Christopher R.; Astin, Matt; Kulasegaram, Kulamakan

2016-01-01

Introduction Online education resources (OERs), like blogs and podcasts, increasingly augment or replace traditional medical education resources such as textbooks and lectures. Trainees’ ability to evaluate these resources is poor, and few quality assessment aids have been developed to assist them. This study aimed to derive a quality evaluation instrument for this purpose. Methods We used a three-phase methodology. In Phase 1, a previously derived list of 151 OER quality indicators was reduced to 13 items using data from published consensus-building studies (of medical educators, expert podcasters, and expert bloggers) and subsequent evaluation by our team. In Phase 2, these 13 items were converted to seven-point Likert scales used by trainee raters (n=40) to evaluate 39 OERs. The reliability and usability of these 13 rating items was determined using responses from trainee raters, and top items were used to create two OER quality evaluation instruments. In Phase 3, these instruments were compared to an external certification process (the ALiEM AIR certification) and the gestalt evaluation of the same 39 blog posts by 20 faculty educators. Results Two quality-evaluation instruments were derived with fair inter-rater reliability: the METRIQ-8 Score (Inter class correlation coefficient [ICC]=0.30, p<0.001) and the METRIQ-5 Score (ICC=0.22, p<0.001). Both scores, when calculated using the derivation data, correlated with educator gestalt (Pearson’s r=0.35, p=0.03 and r=0.41, p<0.01, respectively) and were related to increased odds of receiving an ALiEM AIR certification (odds ratio=1.28, p=0.03; OR=1.5, p=0.004, respectively). Conclusion Two novel scoring instruments with adequate psychometric properties were derived to assist trainees in evaluating OER quality and correlated favourably with gestalt ratings of online educational resources by faculty educators. Further testing is needed to ensure these instruments are accurate when applied by trainees. PMID:27625722

3D Nitrogen, Sulfur-Codoped Carbon Nanomaterial-Supported Cobalt Oxides with Polyhedron-Like Particles Grafted onto Graphene Layers as Highly Active Bicatalysts for Oxygen-Evolving Reactions.

PubMed

Huang, Xiaobo; Wang, Jianqiang; Bao, Hongliang; Zhang, Xiangkun; Huang, Yongmin

2018-02-28

The extensive research and developments of highly efficient oxygen electrode electrocatalysts to get rid of the kinetic barriers for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are very important in energy conversion and storage devices. Especially, exploring nonprecious metal alternatives to replace traditional noble metal catalysts with high cost and poor durability is the paramount mission. In this paper, we utilize property-flexible ZIF-67 and sulfur-functionalized graphene oxide to obtain a cobalt, nitrogen, and sulfur codoped nanomaterial with 3D hierarchical porous structures, owing to their rich dopant species and good conductivity. The crosslinked structures of polyhedron particles throughout the whole carbon framework speeds up the mass transportation and charge-delivery processes during oxygen-evolving reactions. Also, by exploring the location and coordination type of sulfur dopants, we emphasize the effects of sulfone and sulfide functional groups anchored into the graphitic structure on enhancing the catalytic abilities for ORR and OER. To note, compared to the noble metal electrocatalysts, the best-performing CoO@Co 3 O 4 /NSG-650 (0.79 V) is 40 mV less active than the commercial Pt/C catalyst (0.83 V) for ORR and merely 10 mV behind IrO 2 (1.68 V) for OER. Besides, the metric between ORR and OER difference for CoO@Co 3 O 4 /NSG-650 to evaluate its overall electrocatalytic activity is 0.90 V, surpassing 290 and 430 mV over Pt/C (1.19 V) and IrO 2 (1.33 V). Comprehensively, the as-prepared CoO@Co 3 O 4 /NSG-650 indicates excellent bifunctional catalytic activities for ORR and OER, which shows great potential for replacing noble metal catalysts in the application of fuel cells and metal-air batteries.

Mechanistic Investigations of Water Oxidation by a Molecular Cobalt Oxide Analogue: Evidence for a Highly Oxidized Intermediate and Exclusive Terminal Oxo Participation.

PubMed

Nguyen, Andy I; Ziegler, Micah S; Oña-Burgos, Pascual; Sturzbecher-Hohne, Manuel; Kim, Wooyul; Bellone, Donatela E; Tilley, T Don

2015-10-14

Artificial photosynthesis (AP) promises to replace society's dependence on fossil energy resources via conversion of sunlight into sustainable, carbon-neutral fuels. However, large-scale AP implementation remains impeded by a dearth of cheap, efficient catalysts for the oxygen evolution reaction (OER). Cobalt oxide materials can catalyze the OER and are potentially scalable due to the abundance of cobalt in the Earth's crust; unfortunately, the activity of these materials is insufficient for practical AP implementation. Attempts to improve cobalt oxide's activity have been stymied by limited mechanistic understanding that stems from the inherent difficulty of characterizing structure and reactivity at surfaces of heterogeneous materials. While previous studies on cobalt oxide revealed the intermediacy of the unusual Co(IV) oxidation state, much remains unknown, including whether bridging or terminal oxo ligands form O2 and what the relevant oxidation states are. We have addressed these issues by employing a homogeneous model for cobalt oxide, the [Co(III)4] cubane (Co4O4(OAc)4py4, py = pyridine, OAc = acetate), that can be oxidized to the [Co(IV)Co(III)3] state. Upon addition of 1 equiv of sodium hydroxide, the [Co(III)4] cubane is regenerated with stoichiometric formation of O2. Oxygen isotopic labeling experiments demonstrate that the cubane core remains intact during this stoichiometric OER, implying that terminal oxo ligands are responsible for forming O2. The OER is also examined with stopped-flow UV-visible spectroscopy, and its kinetic behavior is modeled, to surprisingly reveal that O2 formation requires disproportionation of the [Co(IV)Co(III)3] state to generate an even higher oxidation state, formally [Co(V)Co(III)3] or [Co(IV)2Co(III)2]. The mechanistic understanding provided by these results should accelerate the development of OER catalysts leading to increasingly efficient AP systems.

Derivation of Two Critical Appraisal Scores for Trainees to Evaluate Online Educational Resources: A METRIQ Study.

PubMed

Chan, Teresa M; Thoma, Brent; Krishnan, Keeth; Lin, Michelle; Carpenter, Christopher R; Astin, Matt; Kulasegaram, Kulamakan

2016-09-01

Online education resources (OERs), like blogs and podcasts, increasingly augment or replace traditional medical education resources such as textbooks and lectures. Trainees' ability to evaluate these resources is poor, and few quality assessment aids have been developed to assist them. This study aimed to derive a quality evaluation instrument for this purpose. We used a three-phase methodology. In Phase 1, a previously derived list of 151 OER quality indicators was reduced to 13 items using data from published consensus-building studies (of medical educators, expert podcasters, and expert bloggers) and subsequent evaluation by our team. In Phase 2, these 13 items were converted to seven-point Likert scales used by trainee raters (n=40) to evaluate 39 OERs. The reliability and usability of these 13 rating items was determined using responses from trainee raters, and top items were used to create two OER quality evaluation instruments. In Phase 3, these instruments were compared to an external certification process (the ALiEM AIR certification) and the gestalt evaluation of the same 39 blog posts by 20 faculty educators. Two quality-evaluation instruments were derived with fair inter-rater reliability: the METRIQ-8 Score (Inter class correlation coefficient [ICC]=0.30, p<0.001) and the METRIQ-5 Score (ICC=0.22, p<0.001). Both scores, when calculated using the derivation data, correlated with educator gestalt (Pearson's r=0.35, p=0.03 and r=0.41, p<0.01, respectively) and were related to increased odds of receiving an ALiEM AIR certification (odds ratio=1.28, p=0.03; OR=1.5, p=0.004, respectively). Two novel scoring instruments with adequate psychometric properties were derived to assist trainees in evaluating OER quality and correlated favourably with gestalt ratings of online educational resources by faculty educators. Further testing is needed to ensure these instruments are accurate when applied by trainees.

Novel Nano-Composite Catalysts for Renewable Energy Storage Applications

NASA Astrophysics Data System (ADS)

Devaguptapu, Surya Vamsi

Spinel NiCo2O4 catalysts are considered the promising precious metal-free catalyst for oxygen reactions. Significant efforts are mainly explore optimal chemical doping and substituent to tune its electronic structures for enhanced performance. Here, we focuses on morphology control and determine the morphology-dependent activity for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In particular, three types of spinel NiCo2O4 were prepared using temple-free, SiO 2 hard template, and Pluronic-123 soft template hydrothermal methods, showing significantly different morphologies, respectively. In particular, template-free method yield dense structures. Sold-template method assists the formation of porous and hollow structures. Importantly, the soft template is effective to prepare a unique nanoflower morphology containing abundant rose petal (needle) like structures. The effect of the utilization of templates, both soft and hard as well as a template free synthesis on the morphology as well as the activity and stability of the final catalyst is investigated. Compared to others, the nanoflower-like NiCo2O4 exhibited the highest bifunctional catalytic activity simultaneously for ORR and OER, likely due to the facile absorption of oxygen molecules on increased surface areas with efficient mass transfer. The nanoflower NiCo2O 4 also exhibited an onset and half-wave potentials of 0.94 and 0.82 V for the ORR in alkaline media. Although it is still inferior to state of the art Pt, the new type of spinel NiCo2O4 catalyst represents the best activity compared to reported carbon-free oxides. Meanwhile, OER activity and stability were achieved with an onset potential of 1.48 V generating a current density of 14 mA/cm2 at 1.6 V. The OER activity does not declined after 10,000 potential cycles demonstrating excellent stability, which is superior to the benchmark of Ir for the OER. This work provides an effective solution to enhance catalytic activity and stability of oxides by engineering their morphology and nanostructures. The high performance bifunctional oxide catalyst is carbon free and can eventually overcome the stability issue for reversible fuel cell and metal-air battery applications. In addition, we have synthesized highly active transition metal doped Carbon Nano Tubes of very small thickness called Graphene Tubes which when integrated with metal oxides can lead to enhanced activity and durability for ORR and OER with current density as high as 25mAcm-2 at 1.6V vs RHE for OER and an onset potential of 1.0V vs RHE during ORR. Finally, we conclude by giving a brief description of the Hydrogen Economy and the role that ammonia decomposition can play in achieving the potential of hydrogen economy. We detail the synthesis procedures of some highly active transition metal nitride- alkali metal imide composites and study their activity for ammonia decomposition. The catalysts show conversion efficiencies as high as 95%.

Hollow structured carbon-supported nickel cobaltite nanoparticles as an efficient bifunctional electrocatalyst for the oxygen reduction and evolution reaction

DOE PAGES

Wang, Jie; Han, Lili; Lin, Ruoqian; ...

2016-01-05

Here, the exploration of efficient electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for fuel cells and metal-air batteries. In this study, we developed 3D hollow-structured NiCo 2O 4/C nanoparticles with interconnected pores as bifunctional electrocatalysts, which are transformed from solid NiCo 2 alloy nanoparticles through the Kirkendall effect. The unique hollow structure of NiCo 2O 4 nanoparticles increases the number of active sites and improves contact with the electrolyte to result in excellent ORR and OER performances. In addition, the hollow-structured NiCo 2O 4/C nanoparticles exhibit superior long-term stability for both themore » ORR and OER compared to commercial Pt/C. The template- and surfactant-free synthetic strategy could be used for the low-cost and large-scale synthesis of hollow-structured materials, which would facilitate the screening of high-efficiency catalysts for energy conversion.« less

Introducing Fe 2+ into Nickel-Iron Layered Double Hydroxide: Local Structure Modulated Water Oxidation Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Zhao; Zhou, Daojin; Wang, Maoyu

Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Here we report the tuning of the local atomic structure of nickel–iron layered double hydroxides (NiFe–LDHs) by partially substituting Ni 2+ with Fe 2+ to introduce Fe–O–Fe moieties. These Fe 2+–containing NiFe–LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA/cm 2, which is among the best OER catalytic performance reported to date. In–situ X–ray absorption, Raman, and electrochemical analysis jointlymore » reveal that the Fe–O–Fe motifs could stabilize high–valent metal sites at low overpotentials, thereby enhancing the OER activity. Lastly, these results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts.« less

Operando Evidence for a Universal Oxygen Evolution Mechanism on Thermal and Electrochemical Iridium Oxides.

PubMed

Saveleva, Viktoriia A; Wang, Li; Teschner, Detre; Jones, Travis; Gago, Aldo S; Friedrich, K Andreas; Zafeiratos, Spyridon; Schlögl, Robert; Savinova, Elena R

2018-06-07

Progress in the development of proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for an understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation-based near-ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers-electrochemical and thermal iridium oxides. Analysis of the O K-edge and Ir 4f spectra backed by density functional calculations reveals a universal oxygen anion red-ox mechanism regardless of the nature (electrochemical or thermal) of the iridium oxide. The formation of molecular oxygen is considered to occur through a chemical step from the electrophilic O I- species, which itself is formed in an electrochemical step.

Hypoxic cell sensitizers and heavy charged-particle radiations.

PubMed Central

Chapman, J. D.; Urtasun, R. C.; Blakely, E. A.; Smith, K. C.; Tobias, C. A.

1978-01-01

Stationary-phase populations of Chinese hamster V-79 cells were irradiated with 250 kV X-rays and the Bragg peaks (spread to a width of 4 cm) of energetic He-, C-, Ne-, and A-ion beams produced at the 184-inch cyclotron and BEVALAC at Lawrence Berkeley Laboratory. Survival curves were generated with each radiation for cells suspended in air-saturated and nitrogen-saturated medium with and without sensitizer present. The oxygen enhancement ratios (OERs) measured for X-rays with 1mM metronidazole and 0.5 mM misonidazole were 2.0 and 1.6 respectively. The OERs without sensitizer for He-, C-, Ne-, and A-ion Bragg peaks were 2.4, 1.7, 1.6 and 1.4 respectively. For each type of radiation tested the presence of hypoxic-cell sensitizers resulted in an additional reduction in the measured OERs, indicating that these drugs should be of benefit in the radiotherapy planned with these and other high LET radiations. PMID:277223

Correlating Oxygen Evolution Catalysts Activity and Electronic Structure by a High-Throughput Investigation of Ni1-y-zFeyCrzOx

PubMed Central

Schwanke, Christoph; Stein, Helge Sören; Xi, Lifei; Sliozberg, Kirill; Schuhmann, Wolfgang; Ludwig, Alfred; Lange, Kathrin M.

2017-01-01

High-throughput characterization by soft X-ray absorption spectroscopy (XAS) and electrochemical characterization is used to establish a correlation between electronic structure and catalytic activity of oxygen evolution reaction (OER) catalysts. As a model system a quasi-ternary materials library of Ni1-y-zFeyCrzOx was synthesized by combinatorial reactive magnetron sputtering, characterized by XAS, and an automated scanning droplet cell. The presence of Cr was found to increase the OER activity in the investigated compositional range. The electronic structure of NiII and CrIII remains unchanged over the investigated composition spread. At the Fe L-edge a linear combination of two spectra was observed. These spectra were assigned to FeIII in Oh symmetry and FeIII in Td symmetry. The ratio of FeIII Oh to FeIII Td increases with the amount of Cr and a correlation between the presence of the FeIII Oh and a high OER activity is found. PMID:28287134

Correlating Oxygen Evolution Catalysts Activity and Electronic Structure by a High-Throughput Investigation of Ni1-y-zFeyCrzOx

NASA Astrophysics Data System (ADS)

Schwanke, Christoph; Stein, Helge Sören; Xi, Lifei; Sliozberg, Kirill; Schuhmann, Wolfgang; Ludwig, Alfred; Lange, Kathrin M.

2017-03-01

High-throughput characterization by soft X-ray absorption spectroscopy (XAS) and electrochemical characterization is used to establish a correlation between electronic structure and catalytic activity of oxygen evolution reaction (OER) catalysts. As a model system a quasi-ternary materials library of Ni1-y-zFeyCrzOx was synthesized by combinatorial reactive magnetron sputtering, characterized by XAS, and an automated scanning droplet cell. The presence of Cr was found to increase the OER activity in the investigated compositional range. The electronic structure of NiII and CrIII remains unchanged over the investigated composition spread. At the Fe L-edge a linear combination of two spectra was observed. These spectra were assigned to FeIII in Oh symmetry and FeIII in Td symmetry. The ratio of FeIII Oh to FeIII Td increases with the amount of Cr and a correlation between the presence of the FeIII Oh and a high OER activity is found.

Role of LiCoO 2 Surface Terminations in Oxygen Reduction and Evolution Kinetics

DOE PAGES

Han, Binghong; Qian, Danna; Risch, Marcel; ...

2015-03-22

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of LiCoO 2 nanorods with sizes in the range from 9 to 40 nm were studied in alkaline solution. The sides of these nanorods were terminated with low-index surfaces such as (003) while the tips were terminated largely with high-index surfaces such as (104) as revealed by high-resolution transmission electron microscopy. Electron energy loss spectroscopy demonstrated that low-spin Co 3+ prevailed on the sides, while the tips exhibited predominantly high- or intermediate-spin Co 3+. We correlated the electronic and atomic structure to higher specific ORR and OER activities at themore » tips as compared to the sides, which was accompanied by more facile redox of Co 2+/3+ and higher charge transferred per unit area. These findings highlight the critical role of surface terminations and electronic structures of transition metal oxides on the ORR and OER activity.« less

Introducing Fe2+ into Nickel-Iron Layered Double Hydroxide: Local Structure Modulated Water Oxidation Activity.

PubMed

Cai, Zhao; Zhou, Daojin; Wang, Maoyu; Bak, Seongmin; Wu, Yueshen; Wu, Zishan; Tian, Yang; Xiong, Xuya; Li, Yaping; Liu, Wen; Siahrostami, Samira; Kuang, Yun; Yang, Xiao-Qing; Duan, Haohong; Feng, Zhenxing; Wang, Hailiang; Sun, Xiaoming

2018-06-11

Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Here we report the tuning of the local atomic structure of nickel-iron layered double hydroxides (NiFe-LDHs) by partially substituting Ni2+ with Fe2+ to introduce Fe-O-Fe moieties. These Fe2+-containing NiFe-LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA/cm2, which is among the best OER catalytic performance reported to date. In-situ X-ray absorption, Raman, and electrochemical analysis jointly reveal that the Fe-O-Fe motifs could stabilize high-valent metal sites at low overpotentials, thereby enhancing the OER activity. These results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Introducing Fe 2+ into Nickel-Iron Layered Double Hydroxide: Local Structure Modulated Water Oxidation Activity

DOE PAGES

Cai, Zhao; Zhou, Daojin; Wang, Maoyu; ...

2018-06-11

Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Here we report the tuning of the local atomic structure of nickel–iron layered double hydroxides (NiFe–LDHs) by partially substituting Ni 2+ with Fe 2+ to introduce Fe–O–Fe moieties. These Fe 2+–containing NiFe–LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA/cm 2, which is among the best OER catalytic performance reported to date. In–situ X–ray absorption, Raman, and electrochemical analysis jointlymore » reveal that the Fe–O–Fe motifs could stabilize high–valent metal sites at low overpotentials, thereby enhancing the OER activity. Lastly, these results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts.« less

Disposable L-lactate biosensor based on a screen-printed carbon electrode enhanced by graphene

NASA Astrophysics Data System (ADS)

Tu, Dandan; He, Yu; Rong, Yuanzhen; Wang, You; Li, Guang

2016-04-01

In this work, an amperometric L-lactate biosensor based on a graphene-modified screen-printed carbon electrode (SPCE) was constructed. First, the electrocatalytic performance of the SPCE modified with graphene by a one-step electrodeposition process (OerGO/SPCE) was investigated. The cyclic voltammogram of OerGO/SPCE, which showed a well-defined redox peak, had a smaller peak potential separation than that of SPCE, revealing the improvement in electron transfer speed brought about by modifying with graphene. Next, lactate oxidase and potassium ferricyanide were dropped on the OerGO/SPCE to construct a graphene-modified L-lactate biosensor (LOD/K3[Fe(CN)6]/OerGO/SPCE). The proposed biosensor, with a detection limit of 60 μM, had a high sensitivity (42.42 μA mM-1 cm-2) when working at a low working potential (0.15 V). The linear range was 0.5 mM-15 mM, covering the detecting range of L-lactate in clinical applications. The L-lactate biosensor had a short response time (10 s) and required only 10 μl of the sample. This L-lactate sensor modified with electrodeposited graphene had a larger sensitivity than that based on the bare SPCE. Thus, our low-cost and disposable L-lactate biosensor enhanced by graphene can perform as an attractive electrochemical device that can be manufactured for point-of-care testing (POCT) devices and be employed in POCT applications.

First-principles study of oxygen evolution reaction on Co doped NiFe-layered double hydroxides

NASA Astrophysics Data System (ADS)

Yu, Jie; Perdew, John; Yan, Qimin

The conversion of solar energy to renewable fuels is a grand challenge. One of the crucial steps for this energy conversion process is the discovery of efficient catalysts with lower overpotential for the oxygen evolution reaction (OER). Layered double hydroxides (LDH) with earth abundant elements such as Ni and Fe have been found as promising OER catalysts and shown to be active for water oxidation. Doping is one of the feasible ways to even lower the overpotential of host materials and breaks the linear scaling law. In this talk we'll present our study on the reaction mechanism of OER on pure and Co-doped NiFe-LDH systems in alkaline solution. We study the absorption energetics of reaction intermediate states and calculate the thermodynamic reaction energy using density functional theory with the PBE +U and the newly developed SCAN functionals. It is shown that the NiFe-LDH system with Co dopants has lower overpotential and higher activity compared with the undoped system. The improvement in activity is related to the presence of Co states in the electronic structure. The work provides a clear clue for the further improvement of the OER activity of LDH systems by chemical doping. The work was supported as part of the Center for the Computational Design of Functional Layered Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

Influence of iron doping on tetravalent nickel content in catalytic oxygen evolving films

PubMed Central

Li, Nancy; Bediako, D. Kwabena; Hadt, Ryan G.; Hayes, Dugan; Kempa, Thomas J.; von Cube, Felix; Bell, David C.; Chen, Lin X.; Nocera, Daniel G.

2017-01-01

Iron doping of nickel oxide films results in enhanced activity for promoting the oxygen evolution reaction (OER). Whereas this enhanced activity has been ascribed to a unique iron site within the nickel oxide matrix, we show here that Fe doping influences the Ni valency. The percent of Fe3+ doping promotes the formation of formal Ni4+, which in turn directly correlates with an enhanced activity of the catalyst in promoting OER. The role of Fe3+ is consistent with its behavior as a superior Lewis acid. PMID:28137835

Influence of iron doping on tetravalent nickel content in catalytic oxygen evolving films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nancy; Bediako, D. Kwabena; Hadt, Ryan G.

2017-01-30

Iron doping of nickel oxide films results in enhanced activity for promoting the oxygen evolution reaction (OER). Whereas this enhanced activity has been ascribed to a unique iron site within the nickel oxide matrix, we show here that Fe doping influences the Ni valency. The percent of Fe3+ doping promotes the formation of formal Ni4+, which in turn directly correlates with an enhanced activity of the catalyst in promoting OER. The role of Fe3+ is consistent with its behavior as a superior Lewis acid.

One-pot fabrication of NiFe2O4 nanoparticles on α-Ni(OH)2 nanosheet for enhanced water oxidation

NASA Astrophysics Data System (ADS)

Chen, Hong; Yan, Junqing; Wu, Huan; Zhang, Yunxia; Liu, Shengzhong (Frank)

2016-08-01

Water splitting has been intensively investigated as a promising solution to resolve the future environmental and energy crises. The oxygen evolution reaction (OER) of the photo- and electric field-induced water splitting limits the development of other reactions, including hydrogen evolution reaction (HER). Fe, Ni and NiFe (hydro) oxide-based catalysts are generally acknowledged among the best candidates of OER catalysts for water splitting. Herein, we developed a one-pot simple hydrothermal process to assemble NiFe2O4 nanoparticles onto the α-Ni(OH)2 nanosheets. The first formed NiFe2O4 under high temperature and pressure environment induces and assists the α-Ni(OH)2 formation without any further additives, because the distance between the neighboring Ni atoms in the cubic NiFe2O4 is similar to that in the α-Ni(OH)2 {003} facets. We have synthesized a series of NiFe2O4/α-Ni(OH)2 compounds and find that the overpotential decreases with the increase of Ni(OH)2 content while the OER kinetics stays unchanged, suggesting that Ni(OH)2 plays a major role in overpotential while NiFe2O4 mainly affects the OER kinetics. The obtained NiFe2O4/α-Ni(OH)2 compounds is also found to be a promising co-catalyst for the photocatalytic water oxidation. In fact, it is even more active than the noble PtOx with acceptable stability for the oxygen generation.

Controlling the Active Sites of Sulfur-Doped Carbon Nanotube-Graphene Nanolobes for Highly Efficient Oxygen Evolution and Reduction Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Sawy, Abdelhamid M.; Mosa, Islam M.; Su, Dong

Controlling active sites of metal-free catalysts is an important strategy to enhance activity of the oxygen evolution reaction (OER). We made many attempts have been made to develop metal-free catalysts, but the lack of understanding of active-sites at the atomic-level has slowed the design of highly active and stable metal-free catalysts. We also developed a sequential two-step strategy to dope sulfur into carbon nanotube–graphene nanolobes. This bidoping strategy introduces stable sulfur–carbon active-sites. Fluorescence emission of the sulfur K-edge by X-ray absorption near edge spectroscopy (XANES) and scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) mapping and spectra confirm thatmore » increasing the incorporation of heterocyclic sulfur into the carbon ring of CNTs not only enhances OER activity with an overpotential of 350 mV at a current density of 10 mA cm -2, but also retains 100% of stability after 75 h. Furthermore, the bidoped sulfur carbon nanotube–graphene nanolobes behave like the state-of-the-art catalysts for OER but outperform those systems in terms of turnover frequency (TOF) which is two orders of magnitude greater than (20% Ir/C) at 400 mV overpotential with very high mass activity 1000 mA cm -2 at 570 mV. Moreover, the sulfur bidoping strategy shows high catalytic activity for the oxygen reduction reaction (ORR). Stable bifunctional (ORR and OER) catalysts are low cost, and light-weight bidoped sulfur carbon nanotubes are potential candidates for next-generation metal-free regenerative fuel cells.« less

Controlling the Active Sites of Sulfur-Doped Carbon Nanotube-Graphene Nanolobes for Highly Efficient Oxygen Evolution and Reduction Catalysis

DOE PAGES

El-Sawy, Abdelhamid M.; Mosa, Islam M.; Su, Dong; ...

2015-12-03

Controlling active sites of metal-free catalysts is an important strategy to enhance activity of the oxygen evolution reaction (OER). We made many attempts have been made to develop metal-free catalysts, but the lack of understanding of active-sites at the atomic-level has slowed the design of highly active and stable metal-free catalysts. We also developed a sequential two-step strategy to dope sulfur into carbon nanotube–graphene nanolobes. This bidoping strategy introduces stable sulfur–carbon active-sites. Fluorescence emission of the sulfur K-edge by X-ray absorption near edge spectroscopy (XANES) and scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) mapping and spectra confirm thatmore » increasing the incorporation of heterocyclic sulfur into the carbon ring of CNTs not only enhances OER activity with an overpotential of 350 mV at a current density of 10 mA cm -2, but also retains 100% of stability after 75 h. Furthermore, the bidoped sulfur carbon nanotube–graphene nanolobes behave like the state-of-the-art catalysts for OER but outperform those systems in terms of turnover frequency (TOF) which is two orders of magnitude greater than (20% Ir/C) at 400 mV overpotential with very high mass activity 1000 mA cm -2 at 570 mV. Moreover, the sulfur bidoping strategy shows high catalytic activity for the oxygen reduction reaction (ORR). Stable bifunctional (ORR and OER) catalysts are low cost, and light-weight bidoped sulfur carbon nanotubes are potential candidates for next-generation metal-free regenerative fuel cells.« less

Boosting Bifunctional Oxygen Electrolysis for N-Doped Carbon via Bimetal Addition.

PubMed

Wang, Jian; Ciucci, Francesco

2017-04-01

The addition of transition metals, even in a trace amount, into heteroatom-doped carbon (M-N/C) is intensively investigated to further enhance oxygen reduction reaction (ORR) activity. However, the influence of metal decoration on the electrolysis of the reverse reaction of ORR, that is, oxygen evolution reaction (OER), is seldom reported. Moreover, further improving the bifunctional activity and corrosion tolerance for carbon-based materials remains a big challenge, especially in OER potential regions. Here, bimetal-decorated, pyridinic N-dominated large-size carbon tubes (MM'-N/C) are proposed for the first time as highly efficient and durable ORR and OER catalysts. FeFe-N/C, CoCo-N/C, NiNi-N/C, MnMn-N/C, FeCo-N/C, NiFe-N/C, FeMn-N/C, CoNi-N/C, MnCo-N/C, and NiMn-N/C are systematically investigated in terms of their structure, composition, morphology, surface area, and active site densities. In contrast to conventional monometal and N-decorated carbon, small amounts of bimetal (≈2 at%) added during the one-step template-free synthesis contribute to increased pyridinic N content, much longer and more robust carbon tubes, reduced metal particle size, and stronger coupling between the encapsulated metals and carbon support. The synergy of those factors accounts for the dramatically improved ORR and OER activity and stability. By comparison, NiFe-N/C and MnCo-N/C stand out and achieve superior bifunctional oxygen catalytic performance, exceeding most of state-of-the-art catalysts. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

DOE PAGES

Kim, Jaemin; Shih, Pei-Chieh; Tsao, Kai-Chieh; ...

2017-07-27

Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge to produce hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y 2Ru 2O 7-δ) electrocatalyst that has significantly enhanced performance toward OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1 M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y 2Ru 2O 7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band centermore » energy for the overlap between Ru 4d and O 2p orbitals and is therefore more stable Ru–O bond than RuO 2, highlighting the effect of yttrium on the enhancement in stability. Finally, the Y 2Ru 2O 7-δ pyrochlore is also free of expensive iridium metal and thus is a cost-effective candidate for practical applications.« less

Multifunctional nanostructured electrocatalysts for energy conversion and storage: current status and perspectives.

PubMed

Ghosh, Srabanti; Basu, Rajendra N

2018-06-21

Electrocatalytic oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) have attracted widespread attention because of their important role in the application of various energy storage and conversion devices, such as fuel cells, metal-air batteries and water splitting devices. However, the sluggish kinetics of the HER/OER/ORR and their dependency on expensive noble metal catalysts (e.g., Pt) obstruct their large-scale application. Hence, the development of efficient and robust bifunctional or trifunctional electrocatalysts in nanodimension for both oxygen reduction/evolution and hydrogen evolution reactions is highly desired and challenging for their commercialization in renewable energy technologies. This review describes some recent developments in the discovery of bifunctional or trifunctional nanostructured catalysts with improved performances for application in rechargeable metal-air batteries and fuel cells. The role of the electronic structure and surface redox chemistry of nanocatalysts in the improvement of their performance for the ORR/OER/HER under an alkaline medium is highlighted and the associated reaction mechanisms developed in the recent literature are also summarized.

A highly active and stable IrO x/SrIrO 3 catalyst for the oxygen evolution reaction

DOE PAGES

Seitz, Linsey C.; Dickens, Colin F.; Nishio, Kazunori; ...

2016-09-02

Oxygen electrochemistry plays a key role in renewable energy technologies such as fuel cells and electrolyzers, but the slow kinetics of the oxygen evolution reaction (OER) limit the performance and commercialization of such devices. Here we report an iridium oxide/strontium iridium oxide (IrO x/SrIrO 3) catalyst formed during electrochemical testing by strontium leaching from surface layers of thin films of SrIrO 3. This catalyst has demonstrated specific activity at 10 milliamps per square centimeter of oxide catalyst (OER current normalized to catalyst surface area), with only 270 to 290 millivolts of overpotential for 30 hours of continuous testing in acidicmore » electrolyte. Here, density functional theory calculations suggest the formation of highly active surface layers during strontium leaching with IrO 3 or anatase IrO 2 motifs. The IrO x/SrIrO 3 catalyst outperforms known IrO x and ruthenium oxide (RuO x) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte.« less

High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jaemin; Shih, Pei-Chieh; Tsao, Kai-Chieh

Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge for the production of hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7-δ) electrocatalyst that has significantly enhanced performance towards OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1-M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y2Ru2O7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band center energy for the overlap betweenmore » Ru 4d and O 2p orbitals and therefore more stable Ru-O bond than RuO2, highlighting the effect of yttrium on the enhancement in stability. The Y2Ru2O7-δ pyrochlore is also free of expensive iridium metal, thus a cost-effective candidate for practical applications.« less

High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jaemin; Shih, Pei-Chieh; Tsao, Kai-Chieh

Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge to produce hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y 2Ru 2O 7-δ) electrocatalyst that has significantly enhanced performance toward OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1 M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y 2Ru 2O 7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band centermore » energy for the overlap between Ru 4d and O 2p orbitals and is therefore more stable Ru–O bond than RuO 2, highlighting the effect of yttrium on the enhancement in stability. Finally, the Y 2Ru 2O 7-δ pyrochlore is also free of expensive iridium metal and thus is a cost-effective candidate for practical applications.« less

Rapid room-temperature synthesis of nanocrystalline spinels as oxygen reduction and evolution electrocatalysts.

PubMed

Cheng, Fangyi; Shen, Jian; Peng, Bo; Pan, Yuede; Tao, Zhanliang; Chen, Jun

2011-01-01

Spinels can serve as alternative low-cost bifunctional electrocatalysts for oxygen reduction/evolution reactions (ORR/OER), which are the key barriers in various electrochemical devices such as metal-air batteries, fuel cells and electrolysers. However, conventional ceramic synthesis of crystalline spinels requires an elevated temperature, complicated procedures and prolonged heating time, and the resulting product exhibits limited electrocatalytic performance. It has been challenging to develop energy-saving, facile and rapid synthetic methodologies for highly active spinels. In this Article, we report the synthesis of nanocrystalline M(x)Mn(3-x)O(4) (M = divalent metals) spinels under ambient conditions and their electrocatalytic application. We show rapid and selective formation of tetragonal or cubic M(x)Mn(3-x)O(4) from the reduction of amorphous MnO(2) in aqueous M(2+) solution. The prepared Co(x)Mn(3-x)O(4) nanoparticles manifest considerable catalytic activity towards the ORR/OER as a result of their high surface areas and abundant defects. The newly discovered phase-dependent electrocatalytic ORR/OER characteristics of Co-Mn-O spinels are also interpreted by experiment and first-principle theoretical studies.

Heterogeneous Electrocatalyst with Molecular Cobalt Ions Serving as the Center of Active Sites.

PubMed

Wang, Jiong; Ge, Xiaoming; Liu, Zhaolin; Thia, Larissa; Yan, Ya; Xiao, Wei; Wang, Xin

2017-02-08

Molecular Co 2+ ions were grafted onto doped graphene in a coordination environment, resulting in the formation of molecularly well-defined, highly active electrocatalytic sites at a heterogeneous interface for the oxygen evolution reaction (OER). The S dopants of graphene are suggested to be one of the binding sites and to be responsible for improving the intrinsic activity of the Co sites. The turnover frequency of such Co sites is greater than that of many Co-based nanostructures and IrO 2 catalysts. Through a series of carefully designed experiments, the pathway for the evolution of the Co cation-based molecular catalyst for the OER was further demonstrated on such a single Co-ion site for the first time. The Co 2+ ions were successively oxidized to Co 3+ and Co 4+ states prior to the OER. The sequential oxidation was coupled with the transfer of different numbers of protons/hydroxides and generated an active Co 4+ ═O fragment. A side-on hydroperoxo ligand of the Co 4+ site is proposed as a key intermediate for the formation of dioxygen.

Tailored Combination of Low Dimensional Catalysts for Efficient Oxygen Reduction and Evolution in Li-O2 Batteries.

PubMed

Yoon, Ki Ro; Kim, Dae Sik; Ryu, Won-Hee; Song, Sung Ho; Youn, Doo-Young; Jung, Ji-Won; Jeon, Seokwoo; Park, Yong Joon; Kim, Il-Doo

2016-08-23

The development of efficient bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key issue pertaining high performance Li-O2 batteries. Here, we propose a heterogeneous electrocatalyst consisting of LaMnO3 nanofibers (NFs) functionalized with RuO2 nanoparticles (NPs) and non-oxidized graphene nanoflakes (GNFs). The Li-O2 cell employing the tailored catalysts delivers an excellent electrochemical performance, affording significantly reduced discharge/charge voltage gaps (1.0 V at 400 mA g(-1) ), and superior cyclability for over 320 cycles. The outstanding performance arises from (1) the networked LaMnO3 NFs providing ORR/OER sites without severe aggregation, (2) the synergistic coupling of RuO2 NPs for further improving the OER activity and the electrical conductivity on the surface of the LaMnO3 NFs, and (3) the use of GNFs providing a fast electronic pathway as well as improved ORR kinetics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Lei; Luo, Langli; Feng, Zhenxing

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and durability. Herein, we report a highly active (360 mV overpotential at 10 mA cm–2GEO) and durable (no degradation after 20000 cycles) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists ofmore » NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron-donation/deviation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

A highly active and stable IrOx/SrIrO3 catalyst for the oxygen evolution reaction.

PubMed

Seitz, Linsey C; Dickens, Colin F; Nishio, Kazunori; Hikita, Yasuyuki; Montoya, Joseph; Doyle, Andrew; Kirk, Charlotte; Vojvodic, Aleksandra; Hwang, Harold Y; Norskov, Jens K; Jaramillo, Thomas F

2016-09-02

Oxygen electrochemistry plays a key role in renewable energy technologies such as fuel cells and electrolyzers, but the slow kinetics of the oxygen evolution reaction (OER) limit the performance and commercialization of such devices. Here we report an iridium oxide/strontium iridium oxide (IrO x /SrIrO 3 ) catalyst formed during electrochemical testing by strontium leaching from surface layers of thin films of SrIrO 3 This catalyst has demonstrated specific activity at 10 milliamps per square centimeter of oxide catalyst (OER current normalized to catalyst surface area), with only 270 to 290 millivolts of overpotential for 30 hours of continuous testing in acidic electrolyte. Density functional theory calculations suggest the formation of highly active surface layers during strontium leaching with IrO 3 or anatase IrO 2 motifs. The IrO x /SrIrO 3 catalyst outperforms known IrO x and ruthenium oxide (RuO x ) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte. Copyright © 2016, American Association for the Advancement of Science.

Directed surfaces structures and interfaces for enhanced electrocatalyst activity, selectivity, and stability for energy conversion reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaramillo, Thomas F.

In this project, we have employed a systematic approach to develop active, selective, and stable catalyst materials for important electrochemical reactions involving energy conversion. In particular, we have focused our attention on developing active catalyst materials for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). HER: We have synthesized and investigated several highly active and acid stable non-precious metal HER catalysts, including: [Mo 3S 13] 2- nanoclusters (Nature Chemistry, 2014) and molybdenum phosphosulfide (MoP|S) (Angewandte Chemie, 2014). We have also aimed to engineer these catalyst formulations in a membrane electrode assembly (MEA) for fundamentalmore » studies of water electrolysis at high current densities, approximately 1 A/cm 2 (ChemSusChem, 2015). We furthermore investigated transition metal phosphide (TMP) catalysts for HER by a combined experimental–theoretical approach (Energy & Environmental Science, 2015). By synthesizing different TMPs and comparing experimentally determined HER activities with the hydrogen adsorption free energies, ΔG H, calculated by density functional theory, we showed that the TMPs follow a volcano relationship for the HER. Using our combined experimental–theoretical model, we predicted that the mixed metal TMP, Fe 0.5Co 0.5P, should have a near-optimal ΔG H. We synthesized several mixtures of Co and Fe phosphides alloys and confirmed that Fe 0.5Co 0.5P exhibits the highest HER activity of the investigated TMPs (Energy & Environmental Science, 2015). The understanding gained as to how to improve catalytic activity for the HER, particularly for non-precious metal materials, is important to DOE targets for sustainable H 2 production. OER: We have developed a SrIrO 3/IrO x catalyst for acidic conditions (submitted, 2016). The SrIrO 3/IrO x catalyst significantly outperforms rutile IrO 2 and RuO 2, the only other OER catalysts to have reasonable stability and activity in acidic electrolyte, and in fact demonstrates the best activity for any known OER catalyst measured in either acidic or in alkaline electrolyte. For alkaline conditions we have demonstrated that the combined effect of cerium as a dopant and gold as a metal support, significantly enhances the OER activity of electrodeposited NiO x films. This NiCeO x-Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts reported to date (Nature Energy, accepted 2016). These studies of new catalysts for the OER, both in acid and in base, are fundamental to enabling new technologies of interest for the DOE, including the production of sustainable fuels and chemicals. ORR: One method to significantly reduce the Pt loading in fuel cell devices is to increase the ORR activity of Pt based systems. To this end we have synthesized a high surface area supported meso-structured Pt xNi alloy thin film with a double gyroid morphology that both exhibits high activity and stability for the ORR (submitted, 2016). We have furthermore developed a Ru-core, Pt-shell system that improves the per Pt site activity by more than a factor of 2 (ChemElectroChem, 2014). Further refinement, optimizing Pt-shell thickness and reducing particle sintering during processing, enabled us to obtain a mass activity that is 2 times higher than commercial Pt/C from TKK. These are important contributions to the DOE goal of reducing Pt loading since an improved understanding of how to increase mass activity and stability helps enable low Pt content fuel cells.« less

Ternary mixed metal Fe-doped NiCo2O4 nanowires as efficient electrocatalysts for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Yan, Kai-Li; Shang, Xiao; Li, Zhen; Dong, Bin; Li, Xiao; Gao, Wen-Kun; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

2017-09-01

Designing mixed metal oxides with unique nanostructures as efficient electrocatalysts for water electrolysis has been an attractive approach for the storage of renewable energies. The ternary mixed metal spinel oxides FexNi1-xCo2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, 1) have been synthesized by a facile hydrothermal approach and calcination treatment using nickel foam as substrate. Fe/Ni ratios have been proved to affect the nanostructures of FexNi1-xCo2O, which imply different intrinsic activity for oxygen evolution reaction (OER). SEM images show that Fe0.5Ni0.5Co2O4 has the uniform nanowires morphology with about 30 nm of the diameter and 200-300 nm of the length. The OER measurements show that Fe0.5Ni0.5Co2O4 exhibits the better electrocatalytic performances with lower overpotential of 350 mV at J = 10 mA cm-2. In addition, the smaller Tafel slope of 27 mV dec-1 than other samples with different Fe/Ni ratios for Fe0.5Ni0.5Co2O4 is obtained. The improved OER activity of Fe0.5Ni0.5Co2O4 may be attributed to the synergistic effects from ternary mixed metals especially Fe-doping and the uniform nanowires supported on NF. Therefore, synthesizing Fe-doped multi-metal oxides with novel nanostructures may be a promising strategy for excellent OER electrocatalysts and it also provides a facile way for the fabrication of high-activity ternary mixed metal oxides electrocatalysts.

OH radicals from the indirect actions of X-rays induce cell lethality and mediate the majority of the oxygen enhancement effect.

PubMed

Hirayama, Ryoichi; Ito, Atsushi; Noguchi, Miho; Matsumoto, Yoshitaka; Uzawa, Akiko; Kobashi, Gen; Okayasu, Ryuichi; Furusawa, Yoshiya

2013-11-01

We examined OH radical-mediated indirect actions from X irradiation on cell killing in wild-type Chinese hamster ovary cell lines (CHO and AA8) under oxic and hypoxic conditions, and compared the contribution of direct and indirect actions under both conditions. The contribution of indirect action on cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide, which suppresses indirect action by quenching OH radicals without affecting the direct action of X rays on cell killing. The contributions of indirect action on cell killing of CHO cells were 76% and 50% under oxic and hypoxic conditions, respectively, and those for AA8 cells were 85% and 47%, respectively. Therefore, the indirect action on cell killing was enhanced by oxygen during X irradiation in both cell lines tested. Oxygen enhancement ratios (OERs) at the 10% survival level (D10 or LD90) for CHO and AA8 cells were 2.68 ± 0.15 and 2.76 ± 0.08, respectively. OERs were evaluated separately for indirect and direct actions, which gave the values of 3.75 and 2.01 for CHO, and 4.11 and 1.32 for AA8 cells, respectively. Thus the generally accepted OER value of ∼3 is best understood as the average of the OER values for both indirect and direct actions. These results imply that both indirect and direct actions on cell killing require oxygen for the majority of lethal DNA damage, however, oxygen plays a larger role in indirect than for direct effects. Conversely, the lethal damage induced by the direct action of X rays are less affected by oxygen concentration.

Cobalt-manganese-based spinels as multifunctional materials that unify catalytic water oxidation and oxygen reduction reactions.

PubMed

Menezes, Prashanth W; Indra, Arindam; Sahraie, Nastaran Ranjbar; Bergmann, Arno; Strasser, Peter; Driess, Matthias

2015-01-01

Recently, there has been much interest in the design and development of affordable and highly efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts that can resolve the pivotal issues that concern solar fuels, fuel cells, and rechargeable metal-air batteries. Here we present the synthesis and application of porous CoMn2 O4 and MnCo2 O4 spinel microspheres as highly efficient multifunctional catalysts that unify the electrochemical OER with oxidant-driven and photocatalytic water oxidation as well as the ORR. The porous materials were prepared by the thermal degradation of the respective carbonate precursors at 400 °C. The as-prepared spinels display excellent performances in electrochemical OER for the cubic MnCo2 O4 phase in comparison to the tetragonal CoMn2 O4 material in an alkaline medium. Moreover, the oxidant-driven and photocatalytic water oxidations were performed and they exhibited a similar trend in activity to that of the electrochemical OER. Remarkably, the situation is reversed in ORR catalysis, that is, the oxygen reduction activity and stability of the tetragonal CoMn2 O4 catalyst outperformed that of cubic MnCo2 O4 and rivals that of benchmark Pt catalysts. The superior catalytic performance and the remarkable stability of the unifying materials are attributed to their unique porous and robust microspherical morphology and the intrinsic structural features of the spinels. Moreover, the facile access to these high-performance materials enables a reliable and cost-effective production on a large scale for industrial applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abreu-Sepulveda, Maria A.; Dhital, Chetan; Huq, Ashfia

The effect due to systematic substitution of cobalt by iron in La 0.6Ca 0.4Co 1-xFe xO 3 towards the oxygen evolution reaction(OER) in alkaline media has been investigated. We synthesized these compounds by a facile glycine-nitrate synthesis and the phase formation was confirmed by X-ray diffraction and Neutron Diffraction elemental analysis. The apparent OER activity was evaluated by quasi steady state current measurements in alkaline media using a traditional three-electrode cell. X-ray photoelectron spectroscopy shows iron substitution causes an increase in the surface concentration of various cobalt oxidation states. Tafel slope in the vicinity of 60 mV/decade and electrochemical reactionmore » order towards OH- near unity were achieved for the unsubstituted La 0.6Ca 0.4CoO 3. Moreover, a decrease in the Tafel slope to 49 mV/decade was observed when iron is substituted in high amounts in the perovskite structure. The area specific current density showed dependence on the Fe fraction, however the relationship of specific current density with Fe fraction is not linear. High Fe substitutions, La 0.6Ca 0.4Co 0.2Fe 0.8O 3 and La 0.6Ca 0.4Co 0.1Fe 0.9O 3 showed higher area specific activity towards OER than La 0.6Ca 0.4CoO 3 or La 0.6Ca 0.4FeO 3. Finally, we believe iron inclusion in the cobalt sites of the perovskite helps decrease the electron transfer barrier and facilitates the formation of cobalt-hydroxide at the surface. Possible OER mechanisms based on the observed kinetic parameters will be discussed.« less

Construction of hierarchically porous graphitized carbon-supported NiFe layered double hydroxides with a core-shell structure as an enhanced electrocatalyst for the oxygen evolution reaction.

PubMed

Ni, Yuanman; Yao, Lihua; Wang, Yin; Liu, Bing; Cao, Minhua; Hu, Changwen

2017-08-17

The oxygen evolution reaction (OER) is a vital half-reaction in water splitting and metal-air batteries. Developing earth-abundant, highly efficient and durable OER catalysts has faced huge challenges until now, because OER is a strict kinetic sluggish process. Herein, we report the construction of hierarchically porous graphitized carbon (HPGC) supported NiFe layered double hydroxides (LDHs) with a core-shell structure (denoted as HPGC@NiFe) by a facile strategy. The HPGC was first obtained by pyrolysing phenolic resin nanospheres with FeCl 3 and ZnCl 2 as the catalyst and the activator, respectively. Then the NiFe LDH arrays were directly grown on the HPGC by a one-step hydrothermal method. The as-synthesized HPGC@NiFe reveals excellent OER properties with a low onset potential, a lower overpotential of 265 mV (corresponding to the current density at 10 mA cm -2 ) and a small Tafel slope (56 mV per decade). And its catalytic activity is even superior to that of the start-of-the-art noble-metal catalyst IrO 2 /C. Notably, the HPGC@NiFe electrode shows admirable stability measured by performing 2000 cycle CVs and long-term electrolysis for 50 h. The prominent performance can be attributed to the synergistic effect between the NiFe-LDHs and the hierarchically porous graphitized carbon, in which the former can increase the exposure of the active sites, while the latter can increase the charge transfer efficiency. Our research implies the possibility for the development of low-cost layered double hydroxides as a promising candidate in electrochemical energy storage and conversion equipment.

Characterization of NiFe oxyhydroxide electrocatalysts by integrated electronic structure calculations and spectroelectrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldsmith, Zachary K.; Harshan, Aparna K.; Gerken, James B.

2017-03-06

NiFe oxyhydroxide materials are highly active electrocatalysts for the oxygen evolution reaction (OER), an important process for carbon-neutral energy storage. Recent spectroscopic and computational studies increasingly support iron as the site of catalytic activity but differ with respect to the relevant iron redox state. A combination of hybrid periodic density functional theory calculations and spectroelectrochemical experiments elucidate the electronic structure and redox thermodynamics of Ni-only and mixed NiFe oxyhydroxide thin-film electrocatalysts. The UV/visible light absorbance of the Ni-only catalyst depends on the applied potential as metal ions in the film are oxidized before the onset of OER activity. In contrast,more » absorbance changes are negligible in a 25% Fe-doped catalyst up to the onset of OER activity. First-principles calculations of proton-coupled redox potentials and magnetizations reveal that the Ni-only system features oxidation of Ni2+ to Ni3+, followed by oxidation to a mixed Ni3+/4+ state at a potential coincident with the onset of OER activity. Calculations on the 25% Fedoped system show the catalyst is redox inert before the onset of catalysis, which coincides with the formation of Fe4+ and mixed Ni oxidation states. The calculations indicate that introduction of Fe dopants changes the character of the conduction band minimum from Ni-oxide in the Ni-only to predominantly Fe-oxide in the NiFe electrocatalyst. These findings provide a unified experimental and theoretical description of the electrochemical and optical properties of Ni and NiFe oxyhydroxide electrocatalysts and serve as an important benchmark for computational characterization of mixedmetal oxidation states in heterogeneous catalysts.« less

Characterization of NiFe oxyhydroxide electrocatalysts by integrated electronic structure calculations and spectroelectrochemistry.

PubMed

Goldsmith, Zachary K; Harshan, Aparna K; Gerken, James B; Vörös, Márton; Galli, Giulia; Stahl, Shannon S; Hammes-Schiffer, Sharon

2017-03-21

NiFe oxyhydroxide materials are highly active electrocatalysts for the oxygen evolution reaction (OER), an important process for carbon-neutral energy storage. Recent spectroscopic and computational studies increasingly support iron as the site of catalytic activity but differ with respect to the relevant iron redox state. A combination of hybrid periodic density functional theory calculations and spectroelectrochemical experiments elucidate the electronic structure and redox thermodynamics of Ni-only and mixed NiFe oxyhydroxide thin-film electrocatalysts. The UV/visible light absorbance of the Ni-only catalyst depends on the applied potential as metal ions in the film are oxidized before the onset of OER activity. In contrast, absorbance changes are negligible in a 25% Fe-doped catalyst up to the onset of OER activity. First-principles calculations of proton-coupled redox potentials and magnetizations reveal that the Ni-only system features oxidation of Ni 2+ to Ni 3+ , followed by oxidation to a mixed Ni 3+/4+ state at a potential coincident with the onset of OER activity. Calculations on the 25% Fe-doped system show the catalyst is redox inert before the onset of catalysis, which coincides with the formation of Fe 4+ and mixed Ni oxidation states. The calculations indicate that introduction of Fe dopants changes the character of the conduction band minimum from Ni-oxide in the Ni-only to predominantly Fe-oxide in the NiFe electrocatalyst. These findings provide a unified experimental and theoretical description of the electrochemical and optical properties of Ni and NiFe oxyhydroxide electrocatalysts and serve as an important benchmark for computational characterization of mixed-metal oxidation states in heterogeneous catalysts.

Characterization of NiFe oxyhydroxide electrocatalysts by integrated electronic structure calculations and spectroelectrochemistry

PubMed Central

Goldsmith, Zachary K.; Harshan, Aparna K.; Gerken, James B.; Galli, Giulia; Stahl, Shannon S.

2017-01-01

NiFe oxyhydroxide materials are highly active electrocatalysts for the oxygen evolution reaction (OER), an important process for carbon-neutral energy storage. Recent spectroscopic and computational studies increasingly support iron as the site of catalytic activity but differ with respect to the relevant iron redox state. A combination of hybrid periodic density functional theory calculations and spectroelectrochemical experiments elucidate the electronic structure and redox thermodynamics of Ni-only and mixed NiFe oxyhydroxide thin-film electrocatalysts. The UV/visible light absorbance of the Ni-only catalyst depends on the applied potential as metal ions in the film are oxidized before the onset of OER activity. In contrast, absorbance changes are negligible in a 25% Fe-doped catalyst up to the onset of OER activity. First-principles calculations of proton-coupled redox potentials and magnetizations reveal that the Ni-only system features oxidation of Ni2+ to Ni3+, followed by oxidation to a mixed Ni3+/4+ state at a potential coincident with the onset of OER activity. Calculations on the 25% Fe-doped system show the catalyst is redox inert before the onset of catalysis, which coincides with the formation of Fe4+ and mixed Ni oxidation states. The calculations indicate that introduction of Fe dopants changes the character of the conduction band minimum from Ni-oxide in the Ni-only to predominantly Fe-oxide in the NiFe electrocatalyst. These findings provide a unified experimental and theoretical description of the electrochemical and optical properties of Ni and NiFe oxyhydroxide electrocatalysts and serve as an important benchmark for computational characterization of mixed-metal oxidation states in heterogeneous catalysts. PMID:28265083

Theoretical investigation of the activity of cobalt oxides for the electrochemical oxidation of water.

PubMed

Bajdich, Michal; García-Mota, Mónica; Vojvodic, Aleksandra; Nørskov, Jens K; Bell, Alexis T

2013-09-11

The presence of layered cobalt oxides has been identified experimentally in Co-based anodes under oxygen-evolving conditions. In this work, we report the results of theoretical investigations of the relative stability of layered and spinel bulk phases of Co oxides, as well as the stability of selected surfaces as a function of applied potential and pH. We then study the oxygen evolution reaction (OER) on these surfaces and obtain activity trends at experimentally relevant electro-chemical conditions. Our calculated volume Pourbaix diagram shows that β-CoOOH is the active phase where the OER occurs in alkaline media. We calculate relative surface stabilities and adsorbate coverages of the most stable low-index surfaces of β-CoOOH: (0001), (0112), and (1014). We find that at low applied potentials, the (1014) surface is the most stable, while the (0112) surface is the more stable at higher potentials. Next, we compare the theoretical overpotentials for all three surfaces and find that the (1014) surface is the most active one as characterized by an overpotential of η = 0.48 V. The high activity of the (1014) surface can be attributed to the observation that the resting state of Co in the active site is Co(3+) during the OER, whereas Co is in the Co(4+) state in the less active surfaces. Lastly, we demonstrate that the overpotential of the (1014) surface can be lowered further by surface substitution of Co by Ni. This finding could explain the experimentally observed enhancement in the OER activity of Ni(y)Co(1-y)O(x) thin films with increasing Ni content. All energetics in this work were obtained from density functional theory using the Hubbard-U correction.

The Influence of Fe Substitution in Lanthanum Calcium Cobalt Oxide on the Oxygen Evolution Reaction in Alkaline Media

DOE PAGES

Abreu-Sepulveda, Maria A.; Dhital, Chetan; Huq, Ashfia; ...

2016-07-30

The effect due to systematic substitution of cobalt by iron in La 0.6Ca 0.4Co 1-xFe xO 3 towards the oxygen evolution reaction(OER) in alkaline media has been investigated. We synthesized these compounds by a facile glycine-nitrate synthesis and the phase formation was confirmed by X-ray diffraction and Neutron Diffraction elemental analysis. The apparent OER activity was evaluated by quasi steady state current measurements in alkaline media using a traditional three-electrode cell. X-ray photoelectron spectroscopy shows iron substitution causes an increase in the surface concentration of various cobalt oxidation states. Tafel slope in the vicinity of 60 mV/decade and electrochemical reactionmore » order towards OH- near unity were achieved for the unsubstituted La 0.6Ca 0.4CoO 3. Moreover, a decrease in the Tafel slope to 49 mV/decade was observed when iron is substituted in high amounts in the perovskite structure. The area specific current density showed dependence on the Fe fraction, however the relationship of specific current density with Fe fraction is not linear. High Fe substitutions, La 0.6Ca 0.4Co 0.2Fe 0.8O 3 and La 0.6Ca 0.4Co 0.1Fe 0.9O 3 showed higher area specific activity towards OER than La 0.6Ca 0.4CoO 3 or La 0.6Ca 0.4FeO 3. Finally, we believe iron inclusion in the cobalt sites of the perovskite helps decrease the electron transfer barrier and facilitates the formation of cobalt-hydroxide at the surface. Possible OER mechanisms based on the observed kinetic parameters will be discussed.« less

Descriptors of Oxygen-Evolution Activity for Oxides: A Statistical Evaluation

DOE PAGES

Hong, Wesley T.; Welsch, Roy E.; Shao-Horn, Yang

2015-12-16

Catalysts for oxygen electrochemical processes are critical for the commercial viability of renewable energy storage and conversion devices such as fuel cells, artificial photosynthesis, and metal-air batteries. Transition metal oxides are an excellent system for developing scalable, non-noble-metal-based catalysts, especially for the oxygen evolution reaction (OER). Central to the rational design of novel catalysts is the development of quantitative structure-activity relation-ships, which correlate the desired catalytic behavior to structural and/or elemental descriptors of materials. The ultimate goal is to use these relationships to guide materials design. In this study, 101 intrinsic OER activities of 51 perovskites were compiled from fivemore » studies in literature and additional measurements made for this work. We explored the behavior and performance of 14 descriptors of the metal-oxygen bond strength using a number of statistical approaches, including factor analysis and linear regression models. We found that these descriptors can be classified into five descriptor families and identify electron occupancy and metal-oxygen covalency as the dominant influences on the OER activity. However, multiple descriptors still need to be considered in order to develop strong predictive relationships, largely outperforming the use of only one or two descriptors (as conventionally done in the field). Here, we confirmed that the number of d electrons, charge-transfer energy (covalency), and optimality of eg occupancy play the important roles, but found that structural factors such as M-O-M bond angle and tolerance factor are relevant as well. With these tools, we demonstrate how statistical learning can be used to draw novel physical insights and combined with data mining to rapidly screen OER electrocatalysts across a wide chemical space.« less

Electrodeposited Co-doped NiSe2 nanoparticles film: a good electrocatalyst for efficient water splitting

NASA Astrophysics Data System (ADS)

Liu, Tingting; Asiri, Abdullah M.; Sun, Xuping

2016-02-01

In this communication, we report that a Co-doped NiSe2 nanoparticles film electrodeposited on a conductive Ti plate (Co0.13Ni0.87Se2/Ti) behaves as a robust electrocatalyst for both HER and OER in strongly basic media, with good activity over a NiSe2/Ti counterpart. This Co0.13Ni0.87Se2/Ti catalytic electrode delivers 10 mA cm-2 at an overpotential of 64 mV for HER and 100 mA cm-2 at an overpotential of 320 mV for OER in 1.0 M KOH. A voltage of only 1.62 V is required to drive 10 mA cm-2 for the two-electrode alkaline water electrolyzer using Co0.13Ni0.87Se2/Ti as an anode and cathode.In this communication, we report that a Co-doped NiSe2 nanoparticles film electrodeposited on a conductive Ti plate (Co0.13Ni0.87Se2/Ti) behaves as a robust electrocatalyst for both HER and OER in strongly basic media, with good activity over a NiSe2/Ti counterpart. This Co0.13Ni0.87Se2/Ti catalytic electrode delivers 10 mA cm-2 at an overpotential of 64 mV for HER and 100 mA cm-2 at an overpotential of 320 mV for OER in 1.0 M KOH. A voltage of only 1.62 V is required to drive 10 mA cm-2 for the two-electrode alkaline water electrolyzer using Co0.13Ni0.87Se2/Ti as an anode and cathode. Electronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c5nr07170d

Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I.

We report that identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Furthermore, we report for the very first time, F doped Cu 1.5Mn 1.5O 4, identified by exploiting theoretical first principles calculations for ORR and OERmore » in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO 2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO 2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.« less

Investigation of Thin Layered Cobalt Oxide Nano-Islands on Gold

NASA Astrophysics Data System (ADS)

Bajdich, Michal; Walton, Alex S.; Fester, Jakob; Arman, Mohammad A.; Osiecki, Jacek; Knudsen, Jan; Vojvodic, Aleksandra; Lauritsen, Jeppe V.

2015-03-01

Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER), but the synergistic effect of contact with gold is yet to be fully understood. The synthesis of three distinct types of thin-layered cobalt oxide nano-islands supported on a single crystal gold (111) substrate is confirmed by combination of STM and XAS methods. In this work, we present DFT+U theoretical investigation of above nano-islands using several previously known structural models. Our calculations confirm stability of two low-oxygen pressure phases: (a) rock-salt Co-O bilayer and (b) wurtzite Co-O quadlayer and single high-oxygen pressure phase: (c) O-Co-O trilayer. The optimized geometries agree with STM structures and calculated oxidation states confirm the conversion from Co2+ to Co3+ found experimentally in XAS. The O-Co-O trilayer islands have the structure of a single layer of CoOOH proposed to be the true active phase for OER catalyst. For that reason, the effect of water on the Pourbaix stabilities of basal planes and edge sites is fully investigated. Lastly, we also present the corresponding OER theoretical overpotentials.

Uniquely confining Cu2S nanoparticles in graphitized carbon fibers for enhanced oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Zhao, Xiaoqian; Liu, Li; Zhang, Yan; Zhang, Huijuan; Wang, Yu

2017-08-01

Up to now, the literature on Cu2S with specific morphology applied to oxygen evolution reaction (OER) in the electrocatalytic field has been limited. In this work, unique peapod-like Cu2S/C exhibiting superb electrocatalytic performance toward OER is successfully synthesized, by employing Cu(OH)2 nanorods as the template and nontoxic glucose as the carbon source and then annealing with sublimed sulfur. It can be seen that this work explores a new application area for Cu2S. More precisely, the novel morphology contributes to increasing the electrochemical active surface area effectively and promoting contact between the Cu2S nanoparticles and the electrolyte. During electrochemical measurements, the peapod-like Cu2S/C shows enhanced electrocatalytic activity with a low overpotential of 401 mV at the current density of 10 mA cm-2 and a Tafel slope of 52 mV dec-1. More importantly, our material is able to maintain stability for at least 8 h at constant potential and the current loss is negligible after 2000 cycles. Obviously, these striking properties fully demonstrate that the peapod-like Cu2S/C as an efficient catalyst shows great promise for OER.

Noble metal-free bifunctional oxygen evolution and oxygen reduction acidic media electro-catalysts

DOE PAGES

Patel, Prasad Prakash; Datta, Moni Kanchan; Velikokhatnyi, Oleg I.; ...

2016-07-06

We report that identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Furthermore, we report for the very first time, F doped Cu 1.5Mn 1.5O 4, identified by exploiting theoretical first principles calculations for ORR and OERmore » in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO 2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO 2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.« less

Systematic Doping of Cobalt into Layered Manganese Oxide Sheets Substantially Enhances Water Oxidation Catalysis.

PubMed

McKendry, Ian G; Thenuwara, Akila C; Shumlas, Samantha L; Peng, Haowei; Aulin, Yaroslav V; Chinnam, Parameswara Rao; Borguet, Eric; Strongin, Daniel R; Zdilla, Michael J

2018-01-16

The effect on the electrocatalytic oxygen evolution reaction (OER) of cobalt incorporation into the metal oxide sheets of the layered manganese oxide birnessite was investigated. Birnessite and cobalt-doped birnessite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and conductivity measurements. A cobalt:manganese ratio of 1:2 resulted in the most active catalyst for the OER. In particular, the overpotential (η) for the OER was 420 mV, significantly lower than the η = 780 mV associated with birnessite in the absence of Co. Furthermore, the Tafel slope for Co/birnessite was 81 mV/dec, in comparison to a Tafel slope of greater than 200 mV/dec for birnessite. For chemical water oxidation catalysis, an 8-fold turnover number (TON) was achieved (h = 70 mmol of O 2 /mol of metal). Density functional theory (DFT) calculations predict that cobalt modification of birnessite resulted in a raising of the valence band edge and occupation of that edge by holes with enhanced mobility during catalysis. Inclusion of extra cobalt beyond the ideal 1:2 ratio was detrimental to catalysis due to disruption of the layered structure of the birnessite phase.

Ni@Ru and NiCo@Ru Core-Shell Hexagonal Nanosandwiches with a Compositionally Tunable Core and a Regioselectively Grown Shell.

PubMed

Hwang, Hyeyoun; Kwon, Taehyun; Kim, Ho Young; Park, Jongsik; Oh, Aram; Kim, Byeongyoon; Baik, Hionsuck; Joo, Sang Hoon; Lee, Kwangyeol

2018-01-01

The development of highly active electrocatalysts is crucial for the advancement of renewable energy conversion devices. The design of core-shell nanoparticle catalysts represents a promising approach to boost catalytic activity as well as save the use of expensive precious metals. Here, a simple, one-step synthetic route is reported to prepare hexagonal nanosandwich-shaped Ni@Ru core-shell nanoparticles (Ni@Ru HNS), in which Ru shell layers are overgrown in a regioselective manner on the top and bottom, and around the center section of a hexagonal Ni nanoplate core. Notably, the synthesis can be extended to NiCo@Ru core-shell nanoparticles with tunable core compositions (Ni 3 Co x @Ru HNS). Core-shell HNS structures show superior electrocatalytic activity for the oxygen evolution reaction (OER) to a commercial RuO 2 black catalyst, with their OER activity being dependent on their core compositions. The observed trend in OER activity is correlated to the population of Ru oxide (Ru 4+ ) species, which can be modulated by the core compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intercalation of Cobalt into the Interlayer of Birnessite Improves Oxygen Evolution Catalysis

DOE PAGES

Thenuwara, Akila C.; Shumlas, Samantha L.; Attanayake, Nuwan H.; ...

2016-10-10

Here we show that the activity of cobalt for the oxygen evolution reaction (OER) can be enhanced by confining it in the interlayer region of birnessite (layered manganese oxide). The cobalt intercalation was verified by employing state-of-the-art characterization techniques such as XRD, Raman and electron microscopy. It is demonstrated that the Co 2+/birnessite electrocatalyst can reach 10 mA cm -2 at an overpotential of 360 mV with near unity Faradaic efficiency. This overpotential is lower than that which can be achieved by using a pure cobalt hydroxide electrocatalyst for the OER. Furthermore, the Co 2+/birnessite catalyst shows no degradation aftermore » 1000 electrochemical cycles.« less

Carbon-based electrocatalysts for advanced energy conversion and storage

PubMed Central

Zhang, Jintao; Xia, Zhenhai; Dai, Liming

2015-01-01

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

Strategic Integration of Open Educational Resources in Higher Education

NASA Astrophysics Data System (ADS)

Schaffert, Sandra

Open Educational Resources (OERs) can be seen as social movement but are also implemented as strategic measures in higher education institutions (HEIs). This chapter describes the current aims and experiences of OERs in HEIs. Starting with definitions and milestones in respect of the current status, this chapter gives an overview of projects and implementation objectives and it describes two concrete case studies, i.e., the Massachusetts Institute of Technology Open CourseWare project and the OpenLearn project at the Open University in the United Kingdom. The aim of this chapter is to give a comprehensive overview to decision makers and policy drivers within higher education organizations, and thus it develops a blueprint of an implementation model.

Natural and accelerated bioremediation research program plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-09-01

This draft plan describes a ten-year program to develop the scientific understanding needed to harness and develop natural and enhanced biogeochemical processes to bioremediate contaminated soils, sediments and groundwater at DOE facilities. The Office of Health and Environmental Research (OHER) developed this program plan, with advice and assistance from DOE`s Office of Environmental Management (EM). The program builds on OHER`s tradition of sponsoring fundamental research in the life and environmental sciences and was motivated by OHER`s and Office of Energy Research`s (OER`s) commitment to supporting DOE`s environmental management mission and the belief that bioremediation is an important part of themore » solution to DOE`s environmental problems.« less

Electrodeposition of Sn-Ni Alloy Coatings for Water-Splitting Application from Alkaline Medium

NASA Astrophysics Data System (ADS)

Shetty, Sandhya; Hegde, A. Chitharanjan

2017-02-01

In this work, Sn-Ni alloy coatings were developed onto the surface of copper from a newly formulated electrolytic bath by a simple and cost-effective electrodeposition technique using gelatin as an additive. The electrocatalytic behavior of coatings deposited at different current densities (c.d.'s) for water-splitting applications, in terms of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), has been researched. The experimental results showed that the electrocatalytic activity of Sn-Ni coatings has a close relationship with its composition, surface morphology, and phase structure depending on the c.d. used, supported by scanning electron microscopy (SEM-EDX) and X-ray diffraction (XRD) analyses. Cyclic voltammetry and chronopotentiometry techniques have demonstrated that Sn-Ni alloy deposited at 4.0 A dm-2 (having 37.6 wt pct Ni) and 1.0 A dm-2 (having 19.6 wt pct Ni) exhibit, respectively, the highest electrocatalytic behavior for HER and OER in 1.0-M KOH solution. Sn-Ni alloy coatings were found to be stable under working conditions of electrolysis, confirmed by electrochemical corrosion tests. High electrocatalytic activity of Sn-Ni alloy coatings for both HER and OER is specific to their composition, surface morphology, and active surface area.

Improved assessment of multiple sclerosis lesion segmentation agreement via detection and outline error estimates

PubMed Central

2012-01-01

Background Presented is the method “Detection and Outline Error Estimates” (DOEE) for assessing rater agreement in the delineation of multiple sclerosis (MS) lesions. The DOEE method divides operator or rater assessment into two parts: 1) Detection Error (DE) -- rater agreement in detecting the same regions to mark, and 2) Outline Error (OE) -- agreement of the raters in outlining of the same lesion. Methods DE, OE and Similarity Index (SI) values were calculated for two raters tested on a set of 17 fluid-attenuated inversion-recovery (FLAIR) images of patients with MS. DE, OE, and SI values were tested for dependence with mean total area (MTA) of the raters' Region of Interests (ROIs). Results When correlated with MTA, neither DE (ρ = .056, p=.83) nor the ratio of OE to MTA (ρ = .23, p=.37), referred to as Outline Error Rate (OER), exhibited significant correlation. In contrast, SI is found to be strongly correlated with MTA (ρ = .75, p < .001). Furthermore, DE and OER values can be used to model the variation in SI with MTA. Conclusions The DE and OER indices are proposed as a better method than SI for comparing rater agreement of ROIs, which also provide specific information for raters to improve their agreement. PMID:22812697

Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

PubMed

Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

2017-09-13

Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

Catalyst Stability Benchmarking for the Oxygen Evolution Reaction: The Importance of Backing Electrode Material and Dissolution in Accelerated Aging Studies.

PubMed

Geiger, Simon; Kasian, Olga; Mingers, Andrea M; Nicley, Shannon S; Haenen, Ken; Mayrhofer, Karl J J; Cherevko, Serhiy

2017-09-18

In searching for alternative oxygen evolution reaction (OER) catalysts for acidic water splitting, fast screening of the material intrinsic activity and stability in half-cell tests is of vital importance. The screening process significantly accelerates the discovery of new promising materials without the need of time-consuming real-cell analysis. In commonly employed tests, a conclusion on the catalyst stability is drawn solely on the basis of electrochemical data, for example, by evaluating potential-versus-time profiles. Herein important limitations of such approaches, which are related to the degradation of the backing electrode material, are demonstrated. State-of-the-art Ir-black powder is investigated for OER activity and for dissolution as a function of the backing electrode material. Even at very short time intervals materials like glassy carbon passivate, increasing the contact resistance and concealing the degradation phenomena of the electrocatalyst itself. Alternative backing electrodes like gold and boron-doped diamond show better stability and are thus recommended for short accelerated aging investigations. Moreover, parallel quantification of dissolution products in the electrolyte is shown to be of great importance for comparing OER catalyst feasibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption

NASA Astrophysics Data System (ADS)

Zheng, Xueli; Zhang, Bo; de Luna, Phil; Liang, Yufeng; Comin, Riccardo; Voznyy, Oleksandr; Han, Lili; García de Arquer, F. Pelayo; Liu, Min; Dinh, Cao Thang; Regier, Tom; Dynes, James J.; He, Sisi; Xin, Huolin L.; Peng, Huisheng; Prendergast, David; Du, Xiwen; Sargent, Edward H.

2018-02-01

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. We took the view that generating transition-metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Here, using density functional theory, we find that the formation energy of desired Ni4+ sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal P. We therefore synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics with in situ soft X-ray absorption spectroscopy (sXAS). In situ sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni4+ under low overpotential conditions. The NiCoFeP catalyst outperforms IrO2 and retains its performance following 100 h of operation. We showcase NiCoFeP in a membrane-free CO2 electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm-2, reducing CO2 into CO and oxidizing H2O to O2 with a 64% electricity-to-chemical-fuel efficiency.

Heteroatom (P, B, or S) incorporated NiFe-based nanocubes as efficient electrocatalysts for the oxygen evolution reaction

DOE PAGES

Xuan, Cuijuan; Wang, Jie; Xia, Weiwei; ...

2018-03-21

Exploring low-cost and highly efficient electrocatalysts toward the oxygen evolution reaction (OER) is of significant importance, although facing great challenges for sustainable energy systems. In this study, amorphous NiFe-based porous nanocubes (Ni–Fe–O–P, Ni–Fe–O–B, and Ni–Fe–O–S) are successfully synthesized via simple and cost-effective one-step calcination of Ni–Fe based metal–organic frameworks (MOFs) and heteroatom containing molecules. The resulting three materials maintain a well-defined porous nanocube morphology with heteroatoms uniformly distributed in the structure. The unique porous structure can effectively provide more active sites and shorten the mass transport distance. Additionally, the introduction of P, B or S can tune the electronic structure,more » which is favorable for accelerating the charge transfer, and may lead to the formation of the higher average oxidative valence of Ni species during the OER process. Benefiting from the above desirable properties, all three materials exhibit excellent OER electrocatalytic activities and outstanding long-term stability in a home-made zinc air battery. Lastly, this work not only provides a general approach for the synthesis of highly efficient electrocatalysts based on earth-abundant elements but also highlights the potential prospects of MOFs in energy conversion and storage devices.« less

General Strategy for the Synthesis of Transition-Metal Phosphide/N-Doped Carbon Frameworks for Hydrogen and Oxygen Evolution.

PubMed

Pu, Zonghua; Zhang, Chengtian; Amiinu, Ibrahim Saana; Li, Wenqiang; Wu, Lin; Mu, Shichun

2017-05-17

Transition metal phosphides (TMPs) have been identified as promising nonprecious metal electrocatalyst for hydrogen evolution reaction (HER) and other energy conversion reactions. Herein, we reported a general strategy for synthesis of a series of TMPs (Fe 2 P, FeP, Co 2 P, CoP, Ni 2 P, and Ni 12 P 5 ) nanoparticles (NPs) with different metal phases embedded in a N-doped carbon (NC) matrix using metal salt, ammonium dihydrogen phosphate, and melamine as precursor with varying molar ratios and thermolysis temperatures. The resultant TMPs can serve as highly active and durable bifunctional electrocatalyst toward HER and oxygen evolution reaction (OER). In particular, the Ni 2 P@NC phase only requires an overpotential of ∼138 mV to derive HER in 0.5 M H 2 SO 4, and ∼320 mV for OER in 1.0 M KOH at the current density of 10 mA cm -2 . Because of the encapsulation of NC that can effectively prevent corrosion of embedded TMP NPs, Ni 2 P@NC exhibits almost unfading catalytic performance even after 10 h under both acidic and alkaline solutions. This synthesis strategy provides a new avenue to exploring TMPs as highly active and stable electrocatalyst for the HER, OER, and other electrochemical applications.

Photoelectrochemical Water Oxidation by GaAs Nanowire Arrays Protected with Atomic Layer Deposited NiO x Electrocatalysts

NASA Astrophysics Data System (ADS)

Zeng, Joy; Xu, Xiaoqing; Parameshwaran, Vijay; Baker, Jon; Bent, Stacey; Wong, H.-S. Philip; Clemens, Bruce

2018-02-01

Photoelectrochemical (PEC) hydrogen production makes possible the direct conversion of solar energy into chemical fuel. In this work, PEC photoanodes consisting of GaAs nanowire (NW) arrays were fabricated, characterized, and then demonstrated for the oxygen evolution reaction (OER). Uniform and periodic GaAs nanowire arrays were grown on a heavily n-doped GaAs substrates by metal-organic chemical vapor deposition selective area growth. The nanowire arrays were characterized using cyclic voltammetry and impedance spectroscopy in a non-aqueous electrochemical system using ferrocene/ferrocenium (Fc/Fc+) as a redox couple, and a maximum oxidation photocurrent of 11.1 mA/cm2 was measured. GaAs NW arrays with a 36 nm layer of nickel oxide (NiO x ) synthesized by atomic layer deposition were then used as photoanodes to drive the OER. In addition to acting as an electrocatalyst, the NiO x layer served to protect the GaAs NWs from oxidative corrosion. Using this strategy, GaAs NW photoanodes were successfully used for the oxygen evolution reaction. This is the first demonstration of GaAs NW arrays for effective OER, and the fabrication and protection strategy developed in this work can be extended to study any other nanostructured semiconductor materials systems for electrochemical solar energy conversion.

Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption

DOE PAGES

Zheng, Xueli; Zhang, Bo; De Luna, Phil; ...

2017-11-20

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. Here, we took the view that generating transition metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Using density functional theory, we find that the formation energy of desired Ni 4+ sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal phosphorus. Here we synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics by employing in situ soft X-ray absorption (sXAS). In situmore » sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni 4+ under low overpotential conditions. NiCoFeP catalyst outperforms IrO 2 and retains its performance following 100 hours of operation. We showcase NiCoFeP in a membrane-free CO 2 electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm -2, reducing CO 2 into CO and oxidizing H 2O to O 2 with a 64% electricity-to-chemical-fuel efficiency.« less

Heteroatom (P, B, or S) incorporated NiFe-based nanocubes as efficient electrocatalysts for the oxygen evolution reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xuan, Cuijuan; Wang, Jie; Xia, Weiwei

Exploring low-cost and highly efficient electrocatalysts toward the oxygen evolution reaction (OER) is of significant importance, although facing great challenges for sustainable energy systems. In this study, amorphous NiFe-based porous nanocubes (Ni–Fe–O–P, Ni–Fe–O–B, and Ni–Fe–O–S) are successfully synthesized via simple and cost-effective one-step calcination of Ni–Fe based metal–organic frameworks (MOFs) and heteroatom containing molecules. The resulting three materials maintain a well-defined porous nanocube morphology with heteroatoms uniformly distributed in the structure. The unique porous structure can effectively provide more active sites and shorten the mass transport distance. Additionally, the introduction of P, B or S can tune the electronic structure,more » which is favorable for accelerating the charge transfer, and may lead to the formation of the higher average oxidative valence of Ni species during the OER process. Benefiting from the above desirable properties, all three materials exhibit excellent OER electrocatalytic activities and outstanding long-term stability in a home-made zinc air battery. Lastly, this work not only provides a general approach for the synthesis of highly efficient electrocatalysts based on earth-abundant elements but also highlights the potential prospects of MOFs in energy conversion and storage devices.« less

Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Xueli; Zhang, Bo; De Luna, Phil

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. Here, we took the view that generating transition metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Using density functional theory, we find that the formation energy of desired Ni 4+ sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal phosphorus. Here we synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics by employing in situ soft X-ray absorption (sXAS). In situmore » sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni 4+ under low overpotential conditions. NiCoFeP catalyst outperforms IrO 2 and retains its performance following 100 hours of operation. We showcase NiCoFeP in a membrane-free CO 2 electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm -2, reducing CO 2 into CO and oxidizing H 2O to O 2 with a 64% electricity-to-chemical-fuel efficiency.« less

Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption.

PubMed

Zheng, Xueli; Zhang, Bo; De Luna, Phil; Liang, Yufeng; Comin, Riccardo; Voznyy, Oleksandr; Han, Lili; García de Arquer, F Pelayo; Liu, Min; Dinh, Cao Thang; Regier, Tom; Dynes, James J; He, Sisi; Xin, Huolin L; Peng, Huisheng; Prendergast, David; Du, Xiwen; Sargent, Edward H

2018-02-01

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. We took the view that generating transition-metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Here, using density functional theory, we find that the formation energy of desired Ni 4+ sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal P. We therefore synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics with in situ soft X-ray absorption spectroscopy (sXAS). In situ sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni 4+ under low overpotential conditions. The NiCoFeP catalyst outperforms IrO 2 and retains its performance following 100 h of operation. We showcase NiCoFeP in a membrane-free CO 2 electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm -2 , reducing CO 2 into CO and oxidizing H 2 O to O 2 with a 64% electricity-to-chemical-fuel efficiency.

Fluorine substituted (Mn,Ir)O 2:F high performance solid solution oxygen evolution reaction electro-catalysts for PEM water electrolysis

DOE PAGES

Ghadge, Shrinath Dattatray; Patel, Prasad Prakash; Datta, Moni Kanchan; ...

2017-03-20

Identification and development of high performance with reduced overpotential (i.e. reduced operating electricity cost) oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane (PEM) based water electrolysis with ultra-low noble metal content (i.e. reduced materials cost) is of significant interest for economic hydrogen production, thus increasing the commercialization potential of PEM water electrolysis. Accordingly, a novel electrocatalyst should exhibit low overpotential, excellent electrochemical activity and durability superior to state of the art noble metal based electro-catalysts (e.g. Pt, IrO 2, RuO 2). Here in this paper, for the very first time to the best of our knowledge, exploiting first-principles theoreticalmore » calculations of the total energies and electronic structures, we have identified a reduced noble metal content fluorine doped solid solution of MnO 2 and IrO 2, denoted as (Mn 1-xIr x)O 2:F (x = 0.2, 0.3, 0.4), OER electrocatalyst system exhibiting lower overpotential and higher current density than the state of the art IrO 2 and other previously reported systems for PEM water electrolysis. The doped solid solution displays an excellent electrochemical performance with a lowest reported onset potential to date of ~1.35 V (vs. RHE), ~80 mV lower than that of IrO 2 (~1.43 V vs. RHE) and ~15 fold (x = 0.3 and 0.4) higher electrochemical activity compared to pure IrO 2. In addition, the system displays excellent long term electrochemical durability, similar to that of IrO 2 in harsh acidic OER operating conditions. Our study therefore demonstrates remarkable, ~60–80% reduction in noble metal content along with lower overpotential and excellent electrochemical performance clearly demonstrating the potential of the (Mn 1-xIr x)O 2:F system as an OER electro-catalyst for PEM water electrolysis.« less

Tracking Catalyst Redox States and Reaction Dynamics in Ni-Fe Oxyhydroxide Oxygen Evolution Reaction Electrocatalysts: The Role of Catalyst Support and Electrolyte pH.

PubMed

Görlin, Mikaela; Ferreira de Araújo, Jorge; Schmies, Henrike; Bernsmeier, Denis; Dresp, Sören; Gliech, Manuel; Jusys, Zenonas; Chernev, Petko; Kraehnert, Ralph; Dau, Holger; Strasser, Peter

2017-02-08

Ni-Fe oxyhydroxides are the most active known electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes and are therefore of great scientific and technological importance in the context of electrochemical energy conversion. Here we uncover, investigate, and discuss previously unaddressed effects of conductive supports and the electrolyte pH on the Ni-Fe(OOH) catalyst redox behavior and catalytic OER activity, combining in situ UV-vis spectro-electrochemistry, operando electrochemical mass spectrometry (DEMS), and in situ cryo X-ray absorption spectroscopy (XAS). Supports and pH > 13 strongly enhanced the precatalytic voltammetric charge of the Ni-Fe oxyhydroxide redox peak couple, shifted them more cathodically, and caused a 2-3-fold increase in the catalytic OER activity. Analysis of DEMS-based faradaic oxygen efficiency and electrochemical UV-vis traces consistently confirmed our voltammetric observations, evidencing both a more cathodic O 2 release and a more cathodic onset of Ni oxidation at higher pH. Using UV-vis, which can monitor the amount of oxidized Ni +3/+4 in situ, confirmed an earlier onset of the redox process at high electrolyte pH and further provided evidence of a smaller fraction of Ni +3/+4 in mixed Ni-Fe centers, confirming the unresolved paradox of a reduced metal redox activity with increasing Fe content. A nonmonotonic super-Nernstian pH dependence of the redox peaks with increasing Fe content-displaying Pourbaix slopes as steep as -120 mV/pH-suggested a two proton-one electron transfer. We explain and discuss the experimental pH effects using refined coupled (PCET) and decoupled proton transfer-electron transfer (PT/ET) schemes involving negatively charged oxygenate ligands generated at Fe centers. Together, we offer new insight into the catalytic reaction dynamics and associated catalyst redox chemistry of the most important class of alkaline OER catalysts.

Fluorine substituted (Mn,Ir)O 2:F high performance solid solution oxygen evolution reaction electro-catalysts for PEM water electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghadge, Shrinath Dattatray; Patel, Prasad Prakash; Datta, Moni Kanchan

Identification and development of high performance with reduced overpotential (i.e. reduced operating electricity cost) oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane (PEM) based water electrolysis with ultra-low noble metal content (i.e. reduced materials cost) is of significant interest for economic hydrogen production, thus increasing the commercialization potential of PEM water electrolysis. Accordingly, a novel electrocatalyst should exhibit low overpotential, excellent electrochemical activity and durability superior to state of the art noble metal based electro-catalysts (e.g. Pt, IrO 2, RuO 2). Here in this paper, for the very first time to the best of our knowledge, exploiting first-principles theoreticalmore » calculations of the total energies and electronic structures, we have identified a reduced noble metal content fluorine doped solid solution of MnO 2 and IrO 2, denoted as (Mn 1-xIr x)O 2:F (x = 0.2, 0.3, 0.4), OER electrocatalyst system exhibiting lower overpotential and higher current density than the state of the art IrO 2 and other previously reported systems for PEM water electrolysis. The doped solid solution displays an excellent electrochemical performance with a lowest reported onset potential to date of ~1.35 V (vs. RHE), ~80 mV lower than that of IrO 2 (~1.43 V vs. RHE) and ~15 fold (x = 0.3 and 0.4) higher electrochemical activity compared to pure IrO 2. In addition, the system displays excellent long term electrochemical durability, similar to that of IrO 2 in harsh acidic OER operating conditions. Our study therefore demonstrates remarkable, ~60–80% reduction in noble metal content along with lower overpotential and excellent electrochemical performance clearly demonstrating the potential of the (Mn 1-xIr x)O 2:F system as an OER electro-catalyst for PEM water electrolysis.« less

Bimetallic NiFe2O4 synthesized via confined carburization in NiFe-MOFs for efficient oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Fang, Zhiqiang; Hao, Zhaomin; Dong, Qingsong; Cui, Yong

2018-04-01

Transition metal oxides that derived from metal-organic framework (MOF) precursor have intensively received attention because of their numerous electrochemical applications. Bimetallic Ni-Fe oxides have been rarely reported on the basis of MOF-related strategy. Herein, a bimetallic NiFe2O4 was successfully synthesized via confined carburization in NiFe-MOF precursors and characterized by XRD, XPS, SEM, and TEM. After conducting an investigation of oxygen evolution reaction (OER), the as-synthesized NiFe2O4 material exhibited good catalytic efficiency and high stability and durability in alkaline media. The as-synthesized NiFe2O4 material would promote the development of MOFs in non-noble-metal OER catalyst.

Enhanced activity of CaFeMg layered double hydroxides-supported gold nanodendrites for the electrochemical evolution of oxygen and hydrogen in alkaline media

NASA Astrophysics Data System (ADS)

Havakeshian, Elaheh; Salavati, Hossein; Taei, Masoumeh; Hasheminasab, Fatemeh; Seddighi, Mohadeseh

2018-02-01

In this study, Au was electrodeposited on a support of CaFeMg layered double hydroxide and then, its catalytic activity was investigated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Field emission scanning electron microscopy images showed that a uniform porous film of aggregated nano-particles of the LDH has been decorated with Au nanodendrite-like structures (AuNDs@LDH). The results obtained from polarization curves, Tafel plots and electrochemical impedance spectroscopy showed that the AuNDs@LDH exhibits lower overpotential, higher current density, faster kinetics and enhanced stability for both of the OER and HER, in comparison with the single AuNPs and LDH catalysts.

Electrochemical investigations of Co3Fe-RGO as a bifunctional catalyst for oxygen reduction and evolution reactions in alkaline media

NASA Astrophysics Data System (ADS)

Kumar, Surender; Kumar, Divyaratan; Kishore, Brij; Ranganatha, Sudhakar; Munichandraiah, Nookala; Venkataramanan, Natarajan S.

2017-10-01

Nanoparticles of Co3Fe alloy is prepared on reduced graphene oxide (RGO) sheets by modified polyol method. Synthesized alloy particles are characterized by various physicochemical techniques. TEM and SEM pictures showed homogeneously dispersed alloy nanoparticles on the RGO sheets. Electrochemistry of alloy nanoparticles is investigated in alkaline medium. The result shows that oxygen evaluation reaction (OER) activity of Co3Fe-RGO is higher than Pt-black particles. RDE studies in alkaline medium shows that oxygen reduction reaction (ORR) follow four electron pathway. It is suggest that Co3Fe-RGO is an efficient non-precious catalyst for oxygen (ORR/OER) reactions in alkaline electrolyte for PEMFC applications.

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE PAGES

Du, Lei; Luo, Langli; Feng, Zhenxing; ...

2017-07-05

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarcity. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides are their low electronic conductivity and durability. The carbon encapsulating transition metal nanoparticles are expected to address these challenges. However, the relationship between precursor compositions and catalyst properties, and the intrinsic functions of each component has been rarely studied. In this paper,more » we report a highly durable (no degradation after 20,000 cycles) and highly active (360 mV overpotential at 10 mA cm –2 GEO) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron–donation/deviation from Fe and tuned lattice and electronic structures of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. Finally, we further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

Single-Crystalline Ultrathin Co 3O 4 Nanosheets with Massive Vacancy Defects for Enhanced Electrocatalysis

DOE PAGES

Cai, Zhao; Bi, Yongmin; Hu, Enyuan; ...

2017-09-18

The role of vacancy defects is demonstrated to be positive in various energy-related processes. However, introducing vacancy defects into single-crystalline nanostructures with given facets and studying their defect effect on electrocatalytic properties remains a great challenge. Here this paper deliberately introduces oxygen defects into single-crystalline ultrathin Co 3O 4 nanosheets with O-terminated {111} facets by mild solvothermal reduction using ethylene glycol under alkaline condition. As-prepared defect-rich Co 3O 4 nanosheets show a low overpotential of 220 mV with a small Tafel slope of 49.1 mV dec -1 for the oxygen evolution reaction (OER), which is among the best Co-based OERmore » catalysts to date and even more active than the state-of-the-art IrO 2 catalyst. Such vacancy defects are formed by balancing with reducing environments under solvothermal conditions, but are surprisingly stable even after 1000 cycles of scanning under OER working conditions. Density functional theory plus U calculation attributes the enhanced performance to the oxygen vacancies and consequently exposed second-layered Co metal sites, which leads to the lowered OER activation energy of 2.26 eV and improved electrical conductivity. Finally, this mild solvothermal reduction concept opens a new door for the understanding and future designing of advanced defect-based electrocatalysts.« less

A lyophilized and thermal two step synthesis of CoFe alloy nanoparticles embedded in N-doped carbon nanosheets/carbon nanotubes for highly-efficient oxygen evolution reaction.

PubMed

Liu, Yang; Li, Feng; Yang, Haidong; Li, Jing; Ma, Ping; Zhu, Yan; Ma, Jiantai

2018-05-22

There is a vital need to explore highly-efficient and stable nonprecious-metal catalysts for oxygen evolution reaction (OER) to reduce the overpotential and further improve the energy conversion efficiency. Herein, we report a unique and cost-effective lyophilized and thermal two step procedure to synthesize high-performance CoFe alloy nanoparticles embedded in N-doped carbon nanosheets interspersed with carbon nanotubes (CoFe-N-CN/CNTs) hybrid. The lyophilization step during catalysts preparation is beneficial to uniform the dispersion of carbon-like precursors and avoid the agglomeration of metal particles. Meanwhile, the inserted CNTs and doped N in this hybrid provide better electrical conductivity, more chemically active sites, improved mass transport capability and effective gas adsorption/release channels. And all these lead to a high specific surface area of 240.67 m2 g-1, favorable stability and remarkable OER activities with an overpotential of only 285 mV at the current density of 10 mA cm-2 and a Tafel slope of 51.09 mV dec-1 in 1.0 M KOH electrolyte, which is even superior to commercial IrO2 catalysts. The CoFe-N-CN/CNTs hybrid thus exhibits great potential as a highly efficient and earth-abundant anode OER electrocatalyst. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrocatalytic performances of LaNi1-xMgxO3 perovskite oxides as bi-functional catalysts for lithium air batteries

NASA Astrophysics Data System (ADS)

Du, Zhenzhen; Yang, Peng; Wang, Long; Lu, Yuhao; Goodenough, J. B.; Zhang, Jian; Zhang, Dawei

2014-11-01

Mg-doped perovskite oxides LaNi1-xMgxO3 (x = 0, 0.08, 0.15) electrocatalysts are synthesized by a sol-gel method using citric acid as complex agent and ethylene glycol as thickening agent. The intrinsic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity of as-prepared perovskite oxides in aqueous electrolyte are examined on a rotating disk electrode (RDE) set up. Li-air primary batteries on the basis of Mg-doped perovskite oxides LaNi1-xMgxO3 (x = 0, 0.08, 0.15) and nonaqueous electrolyte are also fabricated and tested. In terms of the ORR current densities and OER current densities, the performance is enhanced in the order of LaNiO3, LaNi0.92Mg0.08O3 and LaNi0.85Mg0.15O3. Most notably, partially substituting nickel with magnesium suppresses formation of Ni2+ and ensures high concentration of both OER and ORR reaction energy favorable Ni3+ (eg = 1) on the surface of perovskite catalysts. Nonaqueous Li-air primary battery using LaNi0.92Mg0.08O3 and LaNi0.85Mg0.15O3 as the cathode catalysts exhibit improved performances compared with LaNiO3 catalyst, which are consistent with the ORR current densities.

Crumpled rGO-supported Pt-Ir bifunctional catalyst prepared by spray pyrolysis for unitized regenerative fuel cells

NASA Astrophysics Data System (ADS)

Kim, In Gyeom; Nah, In Wook; Oh, In-Hwan; Park, Sehkyu

2017-10-01

Three-dimensional (3D) crumpled reduced graphene oxide supported Pt-Ir alloys that served as bifunctional oxygen catalysts for use in untized regenerative fuel cells were synthesized by a facile spray pyrolysis method. Pt-Ir catalysts supported on rGO (Pt-Ir/rGOs) were physically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) to observe change in composition by heat treatment, alloying, and morphological transition of the catalysts. Their catalytic activities and stabilities for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) conditions were electrochemically investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), potential cycling and hold tests on the rotating disk electrode (RDE). Pt-Ir/rGO with no post heat-treatment (Pt-Ir/rGO_NP) showed a lower activity for ORR and OER although metal nanoparticles decorated on the support are relatively small. However, Pt-Ir/rGO showed remarkably enhanced activity following heat treatment, depending on temperature. Pt-Ir/rGO heat-treated at 600 °C after spray pyrolysis (Pt-Ir/rGO_P600) exhibited a higher activity and stability than a commercially available Pt/C catalyst kept under the ORR condition, and it also revealed a comparable OER activity and durability versus the commercial unsupported Ir catalyst.

Reaction mechanism for oxygen evolution on RuO 2, IrO 2, and RuO 2@IrO 2 core-shell nanocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Zhong; Zhang, Yu; Liu, Shizhong

Iridium dioxide, IrO 2, is second to the most active RuO 2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. In order to improve the activity of IrO 2-based catalysts, we prepared RuO 2@IrO 2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO 2@IrO 2 is threefold that of IrO 2. While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps ofmore » most active catalysts is important for further activity enhancement. Here, we verified theory-proposed sequential water dissociation pathway in which the O—O bond forms on a single metal site, not via coupling of two adsorbed intermediates, by fitting measured polarization curves using a kinetic equation with the free energies of adsorption and activation as the parameters. Consistent with theoretical calculations, we show that the OER activities of IrO 2 and RuO 2@IrO 2 are limited by the formation of O adsorbed phase, while the OOH formation on the adsorbed O limits the reaction rate on RuO 2.« less

Reaction mechanism for oxygen evolution on RuO 2, IrO 2, and RuO 2@IrO 2 core-shell nanocatalysts

DOE PAGES

Ma, Zhong; Zhang, Yu; Liu, Shizhong; ...

2017-10-28

Iridium dioxide, IrO 2, is second to the most active RuO 2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. In order to improve the activity of IrO 2-based catalysts, we prepared RuO 2@IrO 2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO 2@IrO 2 is threefold that of IrO 2. While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps ofmore » most active catalysts is important for further activity enhancement. Here, we verified theory-proposed sequential water dissociation pathway in which the O—O bond forms on a single metal site, not via coupling of two adsorbed intermediates, by fitting measured polarization curves using a kinetic equation with the free energies of adsorption and activation as the parameters. Consistent with theoretical calculations, we show that the OER activities of IrO 2 and RuO 2@IrO 2 are limited by the formation of O adsorbed phase, while the OOH formation on the adsorbed O limits the reaction rate on RuO 2.« less

Sol-flame synthesis of cobalt-doped TiO2 nanowires with enhanced electrocatalytic activity for oxygen evolution reaction.

PubMed

Cai, Lili; Cho, In Sun; Logar, Manca; Mehta, Apurva; He, Jiajun; Lee, Chi Hwan; Rao, Pratap M; Feng, Yunzhe; Wilcox, Jennifer; Prinz, Fritz B; Zheng, Xiaolin

2014-06-28

Doping nanowires (NWs) is of crucial importance for a range of applications due to the unique properties arising from both impurities' incorporation and nanoscale dimensions. However, existing doping methods face the challenge of simultaneous control over the morphology, crystallinity, dopant distribution and concentration at the nanometer scale. Here, we present a controllable and reliable method, which combines versatile solution phase chemistry and rapid flame annealing process (sol-flame), to dope TiO2 NWs with cobalt (Co). The sol-flame doping method not only preserves the morphology and crystallinity of the TiO2 NWs, but also allows fine control over the Co dopant profile by varying the concentration of Co precursor solution. Characterizations of the TiO2:Co NWs show that Co dopants exhibit 2+ oxidation state and substitutionally occupy Ti sites in the TiO2 lattice. The Co dopant concentration significantly affects the oxygen evolution reaction (OER) activity of TiO2:Co NWs, and the TiO2:Co NWs with 12 at% of Co on the surface show the highest OER activity with a 0.76 V reduction of the overpotential with respect to undoped TiO2 NWs. This enhancement of OER activity for TiO2:Co NWs is attributed to both improved surface charge transfer kinetics and increased bulk conductivity.

Cobalt Nanoparticle-Embedded Porous Carbon Nanofibers with Inherent N- and F-Doping as Binder-Free Bifunctional Catalysts for Oxygen Reduction and Evolution Reactions.

PubMed

Singhal, Richa; Kalra, Vibha

2017-01-18

Efficient, low-cost, non-precious metal-based, and stable bifunctional electrocatalysts are key to various energy storage and conversion devices such as regenerative fuel cells and metal-air batteries. In this work, we report cobalt nanoparticle-embedded porous carbon nanofibers with inherent N- and F-doping as binder-free bifunctional electrocatalysts with excellent activity for both the oxygen reduction and oxygen evolution reaction (ORR/OER) in an alkaline medium. Single-step electrospinning of a solution of the polymer mixture (carbon precursor) and the cobalt precursor followed by controlled pyrolysis with an intermediate reduction step in H 2 (to reduce cobalt oxides to cobalt) was utilized to synthesize an integrated freestanding catalyst. The fabricated catalyst with effective structural and electronic interaction between the cobalt metal nanoparticles and the N- and F-doped carbon defect sites showed enhanced catalytic properties compared to the benchmark catalysts for ORR and OER (Pt, Ir, and Ru). The ORR potential at the current density of -3 mA cm -2 was 0.81 V RHE and the OER potential at a current density of 10 mA cm -2 was 1.595 V RHE , resulting in a ΔE of only 0.785 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-Crystalline Ultrathin Co 3O 4 Nanosheets with Massive Vacancy Defects for Enhanced Electrocatalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Zhao; Bi, Yongmin; Hu, Enyuan

The role of vacancy defects is demonstrated to be positive in various energy-related processes. However, introducing vacancy defects into single-crystalline nanostructures with given facets and studying their defect effect on electrocatalytic properties remains a great challenge. Here this paper deliberately introduces oxygen defects into single-crystalline ultrathin Co 3O 4 nanosheets with O-terminated {111} facets by mild solvothermal reduction using ethylene glycol under alkaline condition. As-prepared defect-rich Co 3O 4 nanosheets show a low overpotential of 220 mV with a small Tafel slope of 49.1 mV dec -1 for the oxygen evolution reaction (OER), which is among the best Co-based OERmore » catalysts to date and even more active than the state-of-the-art IrO 2 catalyst. Such vacancy defects are formed by balancing with reducing environments under solvothermal conditions, but are surprisingly stable even after 1000 cycles of scanning under OER working conditions. Density functional theory plus U calculation attributes the enhanced performance to the oxygen vacancies and consequently exposed second-layered Co metal sites, which leads to the lowered OER activation energy of 2.26 eV and improved electrical conductivity. Finally, this mild solvothermal reduction concept opens a new door for the understanding and future designing of advanced defect-based electrocatalysts.« less

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Lei; Luo, Langli; Feng, Zhenxing

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarcity. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides are their low electronic conductivity and durability. The carbon encapsulating transition metal nanoparticles are expected to address these challenges. However, the relationship between precursor compositions and catalyst properties, and the intrinsic functions of each component has been rarely studied. In this paper,more » we report a highly durable (no degradation after 20,000 cycles) and highly active (360 mV overpotential at 10 mA cm –2 GEO) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron–donation/deviation from Fe and tuned lattice and electronic structures of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. Finally, we further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

Cellular glutathione depletion by diethyl maleate or buthionine sulfoximine: no effect of glutathione depletion on the oxygen enhancement ratio

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, J.B.; Russo, A.; Biaglow, J.E.

1983-11-01

The hypoxic and euoxic radiation response for Chinese hamster lung and A549 human lung carcinoma cells was obtained under conditions where their nonprotein thiols, consisting primarily of glutathione (GSH), were depleted by different mechanisms. The GSH conjugating reagent diethylmaleate (DEM) was compared to DL-buthionine-S,R-sulfoximine (BSO), an inhibitor of glutathionine biosynthesis. Each reagent depleted cellular GSH to less than 5% of control values. A 2-h exposure to 0.5 mM DEM or a 4- or 24-h exposure to BSO at 10 or 1 mM, respectively, depleted cellular GSH to less than 5% of control values. Both agents sensitized cells irradiated under airmore » or hypoxic conditions. When GSH levels are lowered to < 5% by both agents, hypoxic DEM-treated cells exhibited slightly greater x-ray sensitization than hypoxic BSO-treated cells. The aerobic and anoxic sensitization of the cells results in the OER's of 2.8 and 3.0 for the DEM- and BSO-treated cells compared to 2.9 for the V79 control A549. BSO-treated cells showed an OER of 3.3 versus 3 for the control. Our results suggest that GSH depletion by either BSO or DEM sensitizes aerobic cells to radiation but does not appreciably alter the OER.« less

When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting.

PubMed

Wang, Dewen; Li, Qun; Han, Ce; Xing, Zhicai; Yang, Xiurong

2018-01-24

The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS 2 nanosheet array on carbon cloth (NiO@Ni/WS 2 /CC) composite. This composite serves as a unique three-dimensional (3D) synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS 2 , but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS 2 . This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO 2 , as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm -2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS 2 . Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

Ni xWO 2.72 nanorods as an efficient electrocatalyst for oxygen evolution reaction

DOE PAGES

Xi, Zheng; Mendoza-Garcia, Adriana; Zhu, Huiyuan; ...

2017-01-13

Ni xWO 2.72 nanorods (NRs) are synthesized by a one-pot reaction of Ni(acac) 2 and WCl 4. In the rod structure, Ni(II) intercalates in the defective perovskite-type WO 2.72 and is stabilized. The Ni xWO 2.72 NRs show the x-dependent electrocatalysis for the oxygen evolution reaction (OER) in 0.1M KOH with Ni 0.78WO 2.72 being the most efficient, even outperforming the commercial Ir-catalyst. Lastly, the synthesis is not limited to Ni xWO 2.72 but can be extended to M xWO 2.72 (M = Co, Fe) as well, providing a new class of oxide-based catalysts for efficient OER and other energymore » conversion reactions.« less

Highly-active oxygen evolution electrocatalyzed by an Fe-doped NiCr2O4 nanoparticle film.

PubMed

Zhao, Jinxiu; Li, Xianghong; Cui, Guanwei; Sun, Xuping

2018-05-11

Alkaline water splitting offers a simple method for the mass production of hydrogen but suffers from the sluggish kinetics of the anodic oxygen evolution reaction (OER). Here, we report on the development of an Fe-doped NiCr2O4 nanoparticle film on Ni foam (Fe-NiCr2O4/NF) as a non-noble-metal OER electrocatalyst with superior catalytic activity at alkaline pH. Such Fe-NiCr2O4/NF demands overpotentials as low as 228 and 318 mV to drive current densities of 20 and 500 mA cm-2, respectively, in 1.0 M KOH. Notably, it also shows strong long-term electrochemical durability with its activity being retained for at least 60 h.

Multi-documents summarization based on clustering of learning object using hierarchical clustering

NASA Astrophysics Data System (ADS)

Mustamiin, M.; Budi, I.; Santoso, H. B.

2018-03-01

The Open Educational Resources (OER) is a portal of teaching, learning and research resources that is available in public domain and freely accessible. Learning contents or Learning Objects (LO) are granular and can be reused for constructing new learning materials. LO ontology-based searching techniques can be used to search for LO in the Indonesia OER. In this research, LO from search results are used as an ingredient to create new learning materials according to the topic searched by users. Summarizing-based grouping of LO use Hierarchical Agglomerative Clustering (HAC) with the dependency context to the user’s query which has an average value F-Measure of 0.487, while summarizing by K-Means F-Measure only has an average value of 0.336.

The S factor--a new derived hemodynamic oxygenation parameter--a useful tool for simplified mathematical modeling of global problems of oxygen transport.

PubMed

Farrell, K; Wasser, T

1997-01-01

We describe a new derived hemodynamic oxygenation parameter, the S factor (S). The factor is based on oxygen delivery and oxygen consumption and can range from -3 to 1. It allows simplified mathematical modeling of clinical problems of oxygen transport and can be applied to many clinical situations. A new hemodynamic oxygenation parameter, the S factor (S), is introduced as an aid to mathematical modeling. It is defined as follows: [formula: see text] (DO2 = oxygen delivery, VO2 = oxygen consumption) S can theoretically vary from -3 (DO2 = VO2) to +1 (VO2 = 0). When DO2/VO2 = 4 (ie. OER = 0.25), S = 0. An S < 0 implies utilization of reserve oxygen transport capacity. An S > 0 implies increased oxygen delivery in relation to oxygen consumption (ie. "shunted oxygen delivery"). By algebraic manipulation and substitution of the components of DO2 into Equation 1: DO2 = Q x Ca x 10 DO2 = Q [(Hb)(Sat)(1.36) + PaO2(.0031)] 10 (2) the following equations can be derived: [formula: see text] [formula: see text] Ca - Cv (Ca = arterial content, Cv = venous content) can be determined by substituting components of oxygen consumption: VO2 = Q (Ca - Cv) x 10 (5) into equation 1 and solving for Ca - Cv. [formula: see text] Equation 6 can be simplified to: [formula: see text] A previously defined relationship between mixed venous PO2 (PvO2) and DO2/VO2 (where calculated P50 is 26.6 +/- 1.0) can be used to modify S in a clinically relevant manner. PvO2 = 5.44D O2/VO2 + 18.16 (8) The relationship between S and PvO2 can be defined by substituting Equation 4 into Equation 1 and solving for PvO2 PvO2 = [21.76/(1-S)] + 18.16 (9) As an example, at a PvO2 of 28 torr (anaerobic threshold), S = -1.2. The relationship between PvO2 and S is shown in Figure 1. S, which can also be defined as 1-4(VO2/DO2) or 1-4(OER), is a useful tool for mathematical modeling of global problems of oxygen transport because the previously derived equations with the S value allow the components of oxygen transport to be interrelated in a clinically relevant manner. Additional advantages of using S in mathematical modeling are: 1. Conceptually it 'fits' in that in regards to the sign (+ or -), as a -S implies utilization of reserve oxygen transport capacity and a +S implies wasted or excess oxygen delivery (shunted). 2. These concepts are easily quantified using the S factor. 3. It 'spreads out' the difference between values for parameters (OER or S) integrating components of oxygen transport, ie. in the 'normal state' regarding oxygen transport, OER = 0.25 and S = 0. At the anaerobic threshold (PvO2 = 28 torr), OER = 0.55 and S = -1.2. Thus, the change in OER from 'normal state' to anaerobic threshold is 0.3 (0.55-0.25) and the change in S is 1.2. This represents a four-fold increase. Four examples of mathematical modeling of global problems of oxygen transport using the S factor are described below.

NOAA Office of Exploration and Research > Public Affairs > OER Symposium

Science.gov Websites

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Controllable Synthesis of Ni xSe (0.5 ≤ x ≤ 1) Nanocrystals for Efficient Rechargeable Zinc-Air Batteries and Water Splitting.

PubMed

Zheng, Xuerong; Han, Xiaopeng; Liu, Hui; Chen, Jianjun; Fu, Dongju; Wang, Jihui; Zhong, Cheng; Deng, Yida; Hu, Wenbin

2018-04-25

The development of earth-abundant, highly active, and corrosion-resistant electrocatalysts to promote the oxygen reduction reaction (ORR) and oxygen and hydrogen evolution reactions (OER/HER) for rechargeable metal-air batteries and water-splitting devices is urgently needed. In this work, Ni x Se (0.5 ≤ x ≤ 1) nanocrystals with different crystal structures and compositions have been controllably synthesized and investigated as potential electrocatalysts for multifunctional ORR, OER, and HER in alkaline conditions. A novel hot-injection process at ambient pressure was developed to control the phase and composition of a series of Ni x Se by simply adjusting the added molar ratio of the nickel resource to triethylenetetramine. Electrochemical analysis reveals that Ni 0.5 Se nanocrystalline exhibits superior OER activity compared to its counterparts and is comparable to RuO 2 in terms of the low overpotential required to reach a current density of 10 mA cm -2 (330 mV), which may benefit from the pyrite-type crystal structure and Se enrichment in Ni 0.5 Se. For the ORR and HER, Ni 0.75 Se nanoparticles achieve the best performance including lower overpotentials and larger apparent current densities. Further investigations demonstrate that Ni 0.75 Se could not only provide an enhanced electrochemical active area but also facilitate electron transfer during the electrocatalytic process, thus contributing to the remarkable catalytic activity. As a practical application, the Ni 0.75 Se electrode enables rechargeable Zn-air battery with a considerable performance including a long cycling lifetime (200 cycles), high specific capacity (609 mA h g -1 based on the consumed Zn), and low overpotential (0.75 V) at 10 mA cm -2 . Meanwhile, the water-splitting cell setup with an anode of Ni 0.5 Se for the HER and a cathode of Ni 0.75 Se for the OER exhibits a considerable performance with low decay in activity of 12.9% under continuous polarization for 10 h. These results suggest the promising potential of nickel selenide nanocrystals as earth-abundant and high-performance electrocatalysts for metal-air batteries and alkaline water splitting.

Morphology Control of Carbon-Free Spinel NiCo 2 O 4 Catalysts for Enhanced Bifunctional Oxygen Reduction and Evolution in Alkaline Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devaguptapu, Surya V.; Hwang, Sooyeon; Karakalos, Stavros

Spinel NiCo 2O 4 is considered a promising precious metal-free catalyst that is also carbon-free for oxygen electrocatalysis. Current efforts mainly focus on optimal chemical doping and substituent to tune its electronic structures for enhanced activity. Here, we study its morphology control and elucidate the morphology-dependent catalyst performance for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Three types of NiCo 2O 4 catalysts with significantly distinct morphologies were prepared using temple-free, Pluronic-123 (P-123) soft, and SiO 2 hard templates, respectively, via hydrothermal methods following by a calcination. While the hard-template yields sphere-like dense structures, soft-template assists themore » formation of a unique nano-needle cluster assembly containing abundant meso- and macro pores. Furthermore, the effect of morphology of NiCo 2O 4 on their corresponding bifunctional catalytic performance was systematically investigated. The flower-like nano-needle assembly NiCo 2O 4 catalyst via the soft template method exhibited the highest catalytic activity and stability for both ORR and OER. In particular, it exhibited an onset and half-wave potentials of 0.94 and 0.82 V vs. RHE, respectively, for the ORR in alkaline media. Although it is still inferior to Pt, the NiCo 2O 4 represents one of the best ORR catalyst compared to other reported carbon-free oxides. Meanwhile, remarkable OER activity and stability were achieved with an onset potential of 1.48 V and a current density of 15 mA/cm 2 at 1.6 V, showing no activity loss after 20,000 potential cycles (0 to 1.9 V). The demonstrated stability is even superior to Ir for the OER. The morphology-controlled approach provides an effective solution to create a robust 3D architecture with increased surface areas and enhanced mass transfer. More importantly, the soft template can yield high degree of spinel crystallinity with ideal stoichiometric ratios between Ni and Co, thus promoting structural integrity with enhanced electrical conductivity and catalytic properties.« less

Morphology Control of Carbon-Free Spinel NiCo 2 O 4 Catalysts for Enhanced Bifunctional Oxygen Reduction and Evolution in Alkaline Media

DOE PAGES

Devaguptapu, Surya V.; Hwang, Sooyeon; Karakalos, Stavros; ...

2017-12-06

Spinel NiCo 2O 4 is considered a promising precious metal-free catalyst that is also carbon-free for oxygen electrocatalysis. Current efforts mainly focus on optimal chemical doping and substituent to tune its electronic structures for enhanced activity. Here, we study its morphology control and elucidate the morphology-dependent catalyst performance for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Three types of NiCo 2O 4 catalysts with significantly distinct morphologies were prepared using temple-free, Pluronic-123 (P-123) soft, and SiO 2 hard templates, respectively, via hydrothermal methods following by a calcination. While the hard-template yields sphere-like dense structures, soft-template assists themore » formation of a unique nano-needle cluster assembly containing abundant meso- and macro pores. Furthermore, the effect of morphology of NiCo 2O 4 on their corresponding bifunctional catalytic performance was systematically investigated. The flower-like nano-needle assembly NiCo 2O 4 catalyst via the soft template method exhibited the highest catalytic activity and stability for both ORR and OER. In particular, it exhibited an onset and half-wave potentials of 0.94 and 0.82 V vs. RHE, respectively, for the ORR in alkaline media. Although it is still inferior to Pt, the NiCo 2O 4 represents one of the best ORR catalyst compared to other reported carbon-free oxides. Meanwhile, remarkable OER activity and stability were achieved with an onset potential of 1.48 V and a current density of 15 mA/cm 2 at 1.6 V, showing no activity loss after 20,000 potential cycles (0 to 1.9 V). The demonstrated stability is even superior to Ir for the OER. The morphology-controlled approach provides an effective solution to create a robust 3D architecture with increased surface areas and enhanced mass transfer. More importantly, the soft template can yield high degree of spinel crystallinity with ideal stoichiometric ratios between Ni and Co, thus promoting structural integrity with enhanced electrical conductivity and catalytic properties.« less

Electrochemical performances of graphene nanoribbons interlacing hollow NiCo oxide nanocages

NASA Astrophysics Data System (ADS)

Zhao, Xiyu; Li, Xinlu; Huang, Yanchun; Su, Zelong; Long, Junjun; Zhang, Shilei; Sha, Junwei; Wu, Tianli; Wang, Ronghua

2017-12-01

A hybrid of graphene nanoribbons (GNRs) interlacing hollow NiCoO2 (G-HNCO) nanocages in a size range of 300 500 nm with rough surface is synthesized by a chemical etching Cu2O templates and followed by GNR interlacing process. The G-HNCO showed high electrochemical performance of oxygen evolution reaction (OER), which exhibited small onset potential of 1.50 V and achieved current densities of 10 mA cm-2 at potentials of 1.62 V. Also, the hybrid delivered high capacitance of 937.8 F g-1 at 1 A g-1 in supercapacitor (SC) tests as well as stable cycling performance in both OER and SC measurements. The approach to synthesize the hybrid is simple and scalable for other graphene nanoribbon-based electrocatalysts. [Figure not available: see fulltext.

Metal-Organic-Framework-Derived Yolk-Shell-Structured Cobalt-Based Bimetallic Oxide Polyhedron with High Activity for Electrocatalytic Oxygen Evolution.

PubMed

Yu, Zhou; Bai, Yu; Liu, Yuxuan; Zhang, Shimin; Chen, Dandan; Zhang, Naiqing; Sun, Kening

2017-09-20

The development of inexpensive, efficient, and environmentally friendly catalysts for oxygen evolution reaction (OER) is of great significant for green energy utilization. Herein, binary metal oxides (M x Co 3-x O 4 , M = Zn, Ni, and Cu) with yolk-shell polyhedron (YSP) structure were fabricated by facile pyrolysis of bimetallic zeolitic imidazolate frameworks (MCo-ZIFs). Benefiting from the synergistic effects of metal ions and the unique yolk-shell structure, M x Co 3-x O 4 YSP displays good OER catalytic activity in alkaline media. Impressively, Zn x Co 3-x O 4 YSP shows a comparable overpotential of 337 mV at 10 mA cm -2 to commercial RuO 2 and exhibits superior long-term durability. The high activity and good stability reveals its promising application.

Two-dimensional boron: Lightest catalyst for hydrogen and oxygen evolution reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mir, Showkat H.; Chakraborty, Sudip, E-mail: sudiphys@gmail.com, E-mail: prakash.jha@cug.ac.in; Wärnå, John

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) have been envisaged on a two-dimensional (2D) boron sheet through electronic structure calculations based on a density functional theory framework. To date, boron sheets are the lightest 2D material and, therefore, exploring the catalytic activity of such a monolayer system would be quite intuitive both from fundamental and application perspectives. We have functionalized the boron sheet (BS) with different elemental dopants like carbon, nitrogen, phosphorous, sulphur, and lithium and determined the adsorption energy for each case while hydrogen and oxygen are on top of the doping site of themore » boron sheet. The free energy calculated from the individual adsorption energy for each functionalized BS subsequently guides us to predict which case of functionalization serves better for the HER or the OER.« less

α-MnO2 nanorods supported on porous graphitic carbon nitride as efficient electrocatalysts for lithium-air batteries

NASA Astrophysics Data System (ADS)

Hang, Yang; Zhang, Chaofeng; Luo, Xiaoman; Xie, Yingshen; Xin, Sen; Li, Yutao; Zhang, Dawei; Goodenough, John B.

2018-07-01

Synthesis of α-MnO2 nanorods grown on porous graphitic carbon nitride (g-C3N4) sheets via a facile hydrothermal treatment gives a porous composite exhibiting higher activity for an air cathode than the individual component of α-MnO2 or porous g-C3N4 for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The porous g-C3N4/α-MnO2 composite also exhibits better performance in a Li-air battery than pure α-MnO2 or XC-72 carbon catalysts, which includes superior discharge capacity, low voltage gap and high cycle stability. The α-MnO2 nanorods catalyze the OER and the porous g-C3N4 sheets catalyze the ORR.

Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

PubMed Central

Knutsen, Turid

2010-01-01

The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM) is investigated. The alkaline oxygen evolution reaction (OER) was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS) in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

Self-Supported Copper Oxide Electrocatalyst for Water Oxidation at Low Overpotential and Confirmation of Its Robustness by Cu K-edge X-ray Absorption Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiang; Cui, Shengsheng; Sun, Zijun

Developing efficient water oxidation catalysts made of earth-abundant elements is a demanding challenge that should be met to fulfill the promise of water splitting for clean energy. Herein we report an annealing approach to synthesize binder-free, self-supported heterogeneous copper oxide (CuO) on conductive electrodes for oxygen evolution reaction (OER), producing electrodes with excellent electrocatalytic properties such as high efficiency, low overpotential, and good stability. The catalysts were grown in situ on fluorine-doped tin oxide (FTO) by electrodeposition from a simple Cu(II) salt solution, followed by annealing at a high temperature. Under optimal conditions, the CuO-based OER catalyst shows an onsetmore » potential of <0.58 V (vs Ag/AgCl) in 1.0 M KOH at pH 13.6. From the Tafel plot, the required overpotentials for current densities of 0.1 and 1.0 mA/cm2 are only 360 and 430 mV, respectively. The structure and the presence of a CuO motif in the catalyst have been identified by high-energy X-ray diffraction (HE-XRD), Cu K-edge X-ray absorption (XAS) spectra including X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). To the best of our knowledge, this represents the best catalytic activity for CuO-based OER catalysts to date.« less

Electrochemical trapping of metastable Mn3+ ions for activation of MnO2 oxygen evolution catalysts.

PubMed

Morgan Chan, Zamyla; Kitchaev, Daniil A; Nelson Weker, Johanna; Schnedermann, Christoph; Lim, Kipil; Ceder, Gerbrand; Tumas, William; Toney, Michael F; Nocera, Daniel G

2018-06-05

Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn 3+ We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn 3+ may be introduced into MnO 2 by an electrochemically induced comproportionation reaction with Mn 2+ and that Mn 3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn 3+ -activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies show that Mn 3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn 3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn 3+ (T d ) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the δ-MnO 2 polymorph incorporating Mn 3+ ions.

Metal-Organic-Framework-Derived Hybrid Carbon Nanocages as a Bifunctional Electrocatalyst for Oxygen Reduction and Evolution.

PubMed

Liu, Shaohong; Wang, Zhiyu; Zhou, Si; Yu, Fengjiao; Yu, Mengzhou; Chiang, Chang-Yang; Zhou, Wuzong; Zhao, Jijun; Qiu, Jieshan

2017-08-01

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are cornerstone reactions for many renewable energy technologies. Developing cheap yet durable substitutes of precious-metal catalysts, especially the bifunctional electrocatalysts with high activity for both ORR and OER reactions and their streamlined coupling process, are highly desirable to reduce the processing cost and complexity of renewable energy systems. Here, a facile strategy is reported for synthesizing double-shelled hybrid nanocages with outer shells of Co-N-doped graphitic carbon (Co-NGC) and inner shells of N-doped microporous carbon (NC) by templating against core-shell metal-organic frameworks. The double-shelled NC@Co-NGC nanocages well integrate the high activity of Co-NGC shells into the robust NC hollow framework with enhanced diffusion kinetics, exhibiting superior electrocatalytic properties to Pt and RuO 2 as a bifunctional electrocatalyst for ORR and OER, and hold a promise as efficient air electrode catalysts in Zn-air batteries. First-principles calculations reveal that the high catalytic activities of Co-NGC shells are due to the synergistic electron transfer and redistribution between the Co nanoparticles, the graphitic carbon, and the doped N species. Strong yet favorable adsorption of an OOH* intermediate on the high density of uncoordinated hollow-site C atoms with respect to the Co lattice in the Co-NGC structure is a vital rate-determining step to achieve excellent bifunctional electrocatalytic activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hollow TiO2@Co9S8 Core–Branch Arrays as Bifunctional Electrocatalysts for Efficient Oxygen/Hydrogen Production

PubMed Central

Deng, Shengjue; Zhong, Yu; Zeng, Yinxiang; Wang, Yadong; Wang, Xiuli; Tu, Jiangping

2017-01-01

Abstract Designing ever more efficient and cost‐effective bifunctional electrocatalysts for oxygen/hydrogen evolution reactions (OER/HER) is greatly vital and challenging. Here, a new type of binder‐free hollow TiO2@Co9S8 core–branch arrays is developed as highly active OER and HER electrocatalysts for stable overall water splitting. Hollow core–branch arrays of TiO2@Co9S8 are readily realized by the rational combination of crosslinked Co9S8 nanoflakes on TiO2 core via a facile and powerful sulfurization strategy. Arising from larger active surface area, richer/shorter transfer channels for ions/electrons, and reinforced structural stability, the as‐obtained TiO2@Co9S8 core–branch arrays show noticeable exceptional electrocatalytic performance, with low overpotentials of 240 and 139 mV at 10 mA cm−2 as well as low Tafel slopes of 55 and 65 mV Dec−1 for OER and HER in alkaline medium, respectively. Impressively, the electrolysis cell based on the TiO2@Co9S8 arrays as both cathode and anode exhibits a remarkably low water splitting voltage of 1.56 V at 10 mA cm−2 and long‐term durability with no decay after 10 d. The versatile fabrication protocol and smart branch‐core design provide a new way to construct other advanced metal sulfides for energy conversion and storage. PMID:29593976

Facile sonochemical synthesis of amorphous NiFe-(oxy)hydroxide nanoparticles as superior electrocatalysts for oxygen evolution reaction.

PubMed

Lee, Eunjik; Park, Ah-Hyeon; Park, Hyun-Uk; Kwon, Young-Uk

2018-01-01

In this work, we present facile synthesis of amorphous Ni/Fe mixed (oxy)hydroxide (NiFe(H)) nanoparticles (NPs) and their electrocatalytic performance for oxygen evolution reaction (OER) in alkaline media. a-NiFe(H) NPs have received lots of attention as OER electrocatalysts with many desirable properties. By using a simple sonochemical route, we prepared amorphous Ni and Fe-alkoxide (NiFe(A)) NPs whose composition can be controlled in the entire composition range (Ni 100-x Fe x , 0≤x≤1). These samples are composed of extremely small NiFe(A) NPs with Ni and Fe atoms homogeneously distributed. NiFe(A) NPs are readily converted into corresponding electrocatalytically active NiFe(H) NP by a simple electrochemical treatment. Electrochemical analysis data show that the OER activity of amorphous NiFe(H) samples follows the volcano-type trend when plotted against the Fe content. Ni 70 Fe 30 (H) sample showed the lowest overpotential of 292mV at 10mAcm -2 geo and the lowest Tafel slope of 30.4mVdec -1 , outperforming IrO x /C (326mV, 41.7mVdec -1 ). Our samples are highly durable based on the chronopotentiometry data at the current density of 10mAcm -2 geo for 2h which show that Ni 70 Fe 30 sample maintains the steady-state potential, contrary to the time-varying IrO x /C. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical Trapping of Metastable Mn3+ Ions for Activation of MnO2 Oxygen Evolution Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumas, William; Chan, Zamyla Morgan; Kitchaev, Daniil A.

Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn3+. We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn3+ may be introduced into MnO2 by an electrochemically induced comproportionation reaction with Mn2+ and that Mn3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn3+-activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies showmore » that Mn3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn3+(Td) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the d-MnO2 polymorph incorporating Mn3+ ions.« less

Two orders of magnitude enhancement in oxygen evolution reactivity on amorphous Ba0.5Sr0.5Co0.8Fe0.2O3−δ nanofilms with tunable oxidation state

PubMed Central

Chen, Gao; Zhou, Wei; Guan, Daqin; Sunarso, Jaka; Zhu, Yanping; Hu, Xuefeng; Zhang, Wei; Shao, Zongping

2017-01-01

Perovskite oxides exhibit potential for use as electrocatalysts in the oxygen evolution reaction (OER). However, their low specific surface area is the main obstacle to realizing a high mass-specific activity that is required to be competitive against the state-of-the-art precious metal–based catalysts. We report the enhanced performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) for the OER with intrinsic activity that is significantly higher than that of the benchmark IrO2, and this result was achieved via fabrication of an amorphous BSCF nanofilm on a surface-oxidized nickel substrate by magnetron sputtering. The surface nickel oxide layer of the Ni substrate and the thickness of the BSCF film were further used to tune the intrinsic OER activity and stability of the BSCF catalyst by optimizing the electronic configuration of the transition metal cations in BSCF via the interaction between the nanofilm and the surface nickel oxide, which enables up to 315-fold enhanced mass-specific activity compared to the crystalline BSCF bulk phase. Moreover, the amorphous BSCF–Ni foam anode coupled with the Pt–Ni foam cathode demonstrated an attractive small overpotential of 0.34 V at 10 mA cm−2 for water electrolysis, with a BSCF loading as low as 154.8 μg cm−2. PMID:28691090

Hollow TiO2@Co9S8 Core-Branch Arrays as Bifunctional Electrocatalysts for Efficient Oxygen/Hydrogen Production.

PubMed

Deng, Shengjue; Zhong, Yu; Zeng, Yinxiang; Wang, Yadong; Wang, Xiuli; Lu, Xihong; Xia, Xinhui; Tu, Jiangping

2018-03-01

Designing ever more efficient and cost-effective bifunctional electrocatalysts for oxygen/hydrogen evolution reactions (OER/HER) is greatly vital and challenging. Here, a new type of binder-free hollow TiO 2 @Co 9 S 8 core-branch arrays is developed as highly active OER and HER electrocatalysts for stable overall water splitting. Hollow core-branch arrays of TiO 2 @Co 9 S 8 are readily realized by the rational combination of crosslinked Co 9 S 8 nanoflakes on TiO 2 core via a facile and powerful sulfurization strategy. Arising from larger active surface area, richer/shorter transfer channels for ions/electrons, and reinforced structural stability, the as-obtained TiO 2 @Co 9 S 8 core-branch arrays show noticeable exceptional electrocatalytic performance, with low overpotentials of 240 and 139 mV at 10 mA cm -2 as well as low Tafel slopes of 55 and 65 mV Dec -1 for OER and HER in alkaline medium, respectively. Impressively, the electrolysis cell based on the TiO 2 @Co 9 S 8 arrays as both cathode and anode exhibits a remarkably low water splitting voltage of 1.56 V at 10 mA cm -2 and long-term durability with no decay after 10 d. The versatile fabrication protocol and smart branch-core design provide a new way to construct other advanced metal sulfides for energy conversion and storage.

Electronic Modulation of Electrocatalytically Active Center of Cu7S4 Nanodisks by Cobalt-Doping for Highly Efficient Oxygen Evolution Reaction.

PubMed

Li, Qun; Wang, Xianfu; Tang, Kai; Wang, Mengfan; Wang, Chao; Yan, Chenglin

2017-12-26

Cu-based electrocatalysts have seldom been studied for water oxidation because of their inferior activity and poor stability regardless of their low cost and environmentally benign nature. Therefore, exploring an efficient way to improve the activity of Cu-based electrocatalysts is very important for their practical application. Modifying electronic structure of the electrocatalytically active center of electrocatalysts by metal doping to favor the electron transfer between catalyst active sites and electrode is an important approach to optimize hydrogen and oxygen species adsorption energy, thus leading to the enhanced intrinsic electrocatalytic activity. Herein, Co-doped Cu 7 S 4 nanodisks were synthesized and investigated as highly efficient electrocatalyst for oxygen evolution reaction (OER) due to the optimized electronic structure of the active center. Density-functional theory (DFT) calculations reveal that Co-engineered Cu 7 S 4 could accelerate electron transfer between Co and Cu sites, thus decrease the energy barriers of intermediates and products during OER, which are crucial for enhanced catalytic properties. As expected, Co-engineered Cu 7 S 4 nanodisks exhibit a low overpotential of 270 mV to achieve current density of 10 mA cm -2 as well as decreased Tafel slope and enhanced turnover frequencies as compared to bare Cu 7 S 4 . This discovery not only provides low-cost and efficient Cu-based electrocatalyst by Co doping, but also exhibits an in-depth insight into the mechanism of the enhanced OER properties.

Morphology controlled synthesis of 2-D Ni-Ni3S2 and Ni3S2 nanostructures on Ni foam towards oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Chaudhari, Nitin Kaduba; Oh, Aram; Sa, Young Jin; Jin, Haneul; Baik, Hionsuck; Kim, Sang Gu; Lee, Suk Joong; Joo, Sang Hoon; Lee, Kwangyeol

2017-03-01

Catalysts for oxygen evolution reactions (OER) are at the heart of key renewable energy technologies, and development of non-precious metal catalysts with high activity and stability remain a great challenge in this field. Among various material candidates, metal sulfides are receiving increasing attention. While morphology-dependent catalytic performances are well established in noble metal-based catalysts, relatively little is known for the morphology‒catalytic performance relationship in metal sulfide catalysts. In this study, uniform spider web-like Ni nanosheets-Ni3S2 and honeycomb-like Ni3S2 structures are deposited on nickel foam (Ni3S2/NF) by a facile one-step hydrothermal synthetic route. When used as an oxygen evolution electrode, the spider web-like Ni-Ni3S2/NF with the large exposed surface area shown excellent catalytic activity and stability with an overpotential of 310 mV to achieve at 10 mA/cm2 and a Tafel slope of 63 mV/dec in alkaline media, which is superior to the honeycomb-like structure without Ni nanosheet. The low Tafel slope of the spider web-like Ni-Ni3S2/NF represents one of the best OER kinetics among nickel sulfide-based OER catalysts. The results point to the fact that performance of the metal sulfide electrocatalysts might be fine-tuned and optimized with morphological controls.

Decorating unoxidized-carbon nanotubes with homogeneous Ni-Co spinel nanocrystals show superior performance for oxygen evolution/reduction reactions

NASA Astrophysics Data System (ADS)

Yang, Jun; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

2017-03-01

We present a new concept for homogeneous spinel nanocrystal-coating on high crystalline pristine-carbon nanotubes (CNTs) for efficient and durable oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Oxidized CNTs have widely been used to functionalize with metal or metal oxides since the defect sites act as anchoring for metal oxide binding. However, such defects on the tubes cause the decrease in electrical conductivity and stability, leading to lower catalyst performance. In the present study, at first, pristine multi-walled carbon nanotubes (MWNTs) were wrapped by pyridine-based polybenzimidazole (PyPBI) to which uniform NixCo3-xO4 nanocrystals were homogeneously deposited by the solvothermal method without damaging the MWNTs, in which PyPBI acted as efficient anchoring sites for the deposition of spinel oxide nanocrystals with ~5 nm size. The obtained catalyst (MWNT-PyPBI-NixCo3-xO4) outperformed most state-of-the-art non-precious metal-based bifunctional catalysts; namely, for OER, the potential at 10 mA cm-2 and Tafel slope in 1 M KOH solution were 1.54 V vs. RHE and 42 mV dec-1, respectively. For ORR, the onset and half-wave potentials are 0.918 V and 0.811 V vs. RHE, respectively. Moreover, the MWNT-PyPBI-NixCo3-xO4 demonstrates an excellent durability for both ORR and OER.

NOAA Ocean Exploration: Science, Education and Ocean Literacy Online and in Social Media

NASA Astrophysics Data System (ADS)

Keener-Chavis, P.

2012-12-01

"Engagement" in ocean science initially might seem like a simple concept, however within an agency like NOAA, with a broad mission and a wide variety of stakeholders, the concept of engagement becomes quite complex. Several years ago, a Kellogg Commission Report was submitted to NOAA's Science Advisory Board to assist the Agency with more closely defining-and refining-how it could more effectively engage with the multiple audiences with which it works. For NOAA, engagement is a two-way relationship that unfolds in a commitment of service to society. It is an Enterprise-wide capability represented in NOAA's Next Generation Strategic Plan and carries the same weight across the Agency as science and technology. NOAA's Office of Ocean Exploration and Research (OER) engages scientists, educators and the public through a variety of online and social media offerings explicitly tied to the exploration science of its expeditions. The principle platform for this engagement is the Ocean Explorer website (http://oceanexplorer.noaa.gov). It is the single point of entry for formal and informal educators and the public to chronicled OER expeditions to little known regions of the world ocean. The site also enables access to live streaming video and audio from the United States' first ship solely dedicated to ocean exploration, the NOAA Ship Okeanos Explorer and the Institute for Exploration's E/V Nautilus. Video includes footage from the remotely operated vehicles, sonar displays, navigation displays, and mapping data displays. Through telepresence technologies and other online communication tools, scientists at remote locations around the world, including Exploration Command Centers, collaborate in deep-sea exploration conducted by the Okeanos Explorer. Those wanting access to the ship's track, oceanographic data, daily updates, web logs, and imagery during an expedition can access the online Okeanos Explorer Digital Atlas. Information on archived expeditions can be accessed through the OER Digital Atlas, a Google map application that displays expedition locations searchable by year, expedition theme or by a text-entry. Information on expedition-specific collection data, education and outreach is also provided. Educators have access to online interactive courses; entitled Why Do We Explore? and How Do We Explore?; that convey the exploration science, capabilities, and assets of the Okeanos Explorer. Hundreds of online lessons, multimedia learning tools, OceanAGE Career Connections and other resources assist educators with bringing authentic ocean exploration and the scientists behind it into classrooms. Live webcasts by San Francisco's Exploratorium and the use of social media; including Twitter, YouTube, Facebook, the Apple iTunes Channel, and conversations with ITunes University have had immediate and profound impacts on OER's ability to successfully engage diverse partners with a ride range of ocean exploration science and education needs. This presentation will highlight several OER's approaches to engaging scientists, educators and others in ocean exploration, including efforts associated with the upcoming Fall 2012 Submarine Ring of Fire: Lau Basin Expedition onboard the Scripps Institution of Oceanography R/V Roger Revelle.

Odor Sampling: Techniques and Strategies for the Estimation of Odor Emission Rates from Different Source Types

PubMed Central

Capelli, Laura; Sironi, Selena; Rosso, Renato Del

2013-01-01

Sampling is one of the main issues pertaining to odor characterization and measurement. The aim of sampling is to obtain representative information on the typical characteristics of an odor source by means of the collection of a suitable volume fraction of the effluent. The most important information about an emission source for odor impact assessment is the so-called Odor Emission Rate (OER), which represents the quantity of odor emitted per unit of time, and is expressed in odor units per second (ou·s−1). This paper reviews the different odor sampling strategies adopted depending on source type. The review includes an overview of odor sampling regulations and a detailed discussion of the equipment to be used as well as the mathematical considerations to be applied to obtain the OER in relation to the sampled source typology. PMID:23322098

Electrodeposited-film electrodes derived from a precursor dinitrosyl iron complex for electrocatalytic water splitting.

PubMed

Li, Wei-Liang; Chiou, Tzung-Wen; Chen, Chien-Hong; Yu, Yi-Ju; Chu, Li-Kang; Liaw, Wen-Feng

2018-05-29

In artificial photosynthesis, water splitting plays an important role for the conversion and storage of renewable energy sources. Here, we report a study on the electrocatalytic properties of the electrodeposited-film electrodes derived from irreversible electro-reduction/-oxidation of a molecular dinitrosyl iron complex (DNIC) {Fe(NO)2}9 [(Me6tren)Fe(NO)2]+ (Me6tren = tris[2-(dimethylamino)ethyl]amine) for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline solution, individually. For HER, the overpotential and Tafel slope for the electrodeposited-film cathode are lower than those of the equiv.-weight Pt/C electrode. The electrodeposited-film anode for the OER is stable for 139 h. Integration of the electrodeposited-film cathode and anode into a single electrode-pair device for electrocatalytic water splitting exhibits an onset voltage of 1.77 V, achieving a geometrical current density of 10 mA cm-2.

Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances.

PubMed

Gao, Qiuyue; Shi, Zhenyu; Xue, Kaiming; Ye, Ziran; Hong, Zhanglian; Yu, Xinyao; Zhi, Mingjia

2018-05-25

This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co 9 S 8 aerogel with a high surface area (274.2 m 2 g -1 ) and large pore volume (0.87 cm 3 g -1 ) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co 9 S 8 aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g -1 at 1 A g -1 ), good rate capability (74.3% capacitance retention from 1 to 20 A g -1 ) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances

NASA Astrophysics Data System (ADS)

Gao, Qiuyue; Shi, Zhenyu; Xue, Kaiming; Ye, Ziran; Hong, Zhanglian; Yu, Xinyao; Zhi, Mingjia

2018-05-01

This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co9S8 aerogel with a high surface area (274.2 m2 g‑1) and large pore volume (0.87 cm3 g‑1) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co9S8 aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g‑1 at 1 A g‑1), good rate capability (74.3% capacitance retention from 1 to 20 A g‑1) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

Stabilized CdSe-CoPi composite photoanode for light-assisted water oxidation by transformation of a CdSe/cobalt metal thin film.

PubMed

Costi, Ronny; Young, Elizabeth R; Bulović, Vladimir; Nocera, Daniel G

2013-04-10

Integration of water splitting catalysts with visible-light-absorbing semiconductors would enable direct solar-energy-to-fuel conversion schemes such as those based on water splitting. A disadvantage of some common semiconductors that possess desirable optical bandgaps is their chemical instability under the conditions needed for oxygen evolution reaction (OER). In this study, we demonstrate the dual benefits gained from using a cobalt metal thin-film as the precursor for the preparation of cobalt-phosphate (CoPi) OER catalyst on cadmium chalcogenide photoanodes. The cobalt layer protects the underlying semiconductor from oxidation and degradation while forming the catalyst and simultaneously facilitates the advantageous incorporation of the cadmium chalcogenide layer into the CoPi layer during continued processing of the electrode. The resulting hybrid material forms a stable photoactive anode for light-assisted water splitting.

Pulse electrodeposition of CoFe thin films covered with layered double hydroxides as a fast route to prepare enhanced catalysts for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Sakita, Alan M. P.; Noce, Rodrigo Della; Vallés, Elisa; Benedetti, Assis V.

2018-03-01

A novel, ultra-fast, and one-step method for obtaining an effective catalyst for oxygen evolution reaction is proposed. The procedure consists in direct electrodeposition, in a free-nitrate bath, of CoFe alloy films covered with layered double hydroxides (LDH), by potentiostatic mode, in continuous or pulsed regime. The catalyst is directly formed on glassy carbon substrates. The best-prepared catalyst material reveals a mixed morphology with granular and dendritic CoFe alloy covered with a sponge of CoFe-LDH containing a Cl interlayer. An overpotential of η10 mA = 286 mV, with a Tafel slope of 48 mV dec-1, is obtained for the OER which displays the enhanced properties of the catalyst. These improved results demonstrate the competitiveness and efficacy of our proposal for the production of OER catalysts.

Odor sampling: techniques and strategies for the estimation of odor emission rates from different source types.

PubMed

Capelli, Laura; Sironi, Selena; Del Rosso, Renato

2013-01-15

Sampling is one of the main issues pertaining to odor characterization and measurement. The aim of sampling is to obtain representative information on the typical characteristics of an odor source by means of the collection of a suitable volume fraction of the effluent. The most important information about an emission source for odor impact assessment is the so-called Odor Emission Rate (OER), which represents the quantity of odor emitted per unit of time, and is expressed in odor units per second (ou∙s-1). This paper reviews the different odor sampling strategies adopted depending on source type. The review includes an overview of odor sampling regulations and a detailed discussion of the equipment to be used as well as the mathematical considerations to be applied to obtain the OER in relation to the sampled source typology.

A multiscale physical model for the transient analysis of PEM water electrolyzer anodes.

PubMed

Oliveira, Luiz Fernando L; Laref, Slimane; Mayousse, Eric; Jallut, Christian; Franco, Alejandro A

2012-08-07

Polymer electrolyte membrane water electrolyzers (PEMWEs) are electrochemical devices that can be used for the production of hydrogen. In a PEMWE the anode is the most complex electrode to study due to the high overpotential of the oxygen evolution reaction (OER), not widely understood. A physical bottom-up multi-scale transient model describing the operation of a PEMWE anode is proposed here. This model includes a detailed description of the elementary OER kinetics in the anode, a description of the non-equilibrium behavior of the nanoscale catalyst-electrolyte interface, and a microstructural-resolved description of the transport of charges and O(2) at the micro and mesoscales along the whole anode. The impact of different catalyst materials on the performance of the PEMWE anode, and a study of sensitivity to the operation conditions are evaluated from numerical simulations and the results are discussed in comparison with experimental data.

One-Dimensional RuO2/Mn2O3 Hollow Architectures as Efficient Bifunctional Catalysts for Lithium-Oxygen Batteries.

PubMed

Yoon, Ki Ro; Lee, Gil Yong; Jung, Ji-Won; Kim, Nam-Hoon; Kim, Sang Ouk; Kim, Il-Doo

2016-03-09

Rational design and massive production of bifunctional catalysts with fast oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics are critical to the realization of highly efficient lithium-oxygen (Li-O2) batteries. Here, we first exploit two types of double-walled RuO2 and Mn2O3 composite fibers, i.e., (i) phase separated RuO2/Mn2O3 fiber-in-tube (RM-FIT) and (ii) multicomposite RuO2/Mn2O3 tube-in-tube (RM-TIT), by controlling ramping rate during electrospinning process. Both RM-FIT and RM-TIT exhibited excellent bifunctional electrocatalytic activities in alkaline media. The air electrodes using RM-FIT and RM-TIT showed enhanced overpotential characteristics and stable cyclability over 100 cycles in the Li-O2 cells, demonstrating high potential as efficient OER and ORR catalysts.

High-Performance Overall Water Splitting Electrocatalysts Derived from Cobalt-Based Metal–Organic Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Bo; Jiang, Nan; Sheng, Meili

2015-11-05

The design of active, robust, and nonprecious electrocatalysts with both H 2 and O 2 evolution reaction (HER and OER) activities for overall water splitting is highly desirable but remains a grand challenge. Here in this article, we report a facile two-step method to synthesize porous Co-P/NC nanopolyhedrons composed of CoP x (a mixture of CoP and Co 2P) nanoparticles embedded in N-doped carbon matrices as electrocatalysts for overall water splitting. The Co-P/NC catalysts were prepared by direct carbonization of Co-based zeolitic imidazolate framework (ZIF-67) followed by phosphidation. Benefiting from the large specific surface area, controllable pore texture, and highmore » nitrogen content of ZIF (a subclass of metal–organic frameworks), the optimal Co-P/NC showed high specific surface area of 183 m 2 g -1 and large mesopores, and exhibited remarkable catalytic performance for both HER and OER in 1.0 M KOH, affording a current density of 10 mA cm -2 at low overpotentials of -154 mV for HER and 319 mV for OER, respectively. Furthermore, a Co-P/NC-based alkaline electrolyzer approached 165 mA cm -2 at 2.0 V, superior to that of Pt/IrO 2 couple, along with strong stability. Various characterization techniques including X-ray absorption spectroscopy (XAS) revealed that the superior activity and strong stability of Co-P/NC originated from its 3D interconnected mesoporosity with high specific surface area, high conductivity, and synergistic effect of CoP x encapsulated within N-doped carbon matrices.« less

Extraction of nickel from NiFe-LDH into Ni2P@NiFe hydroxide as a bifunctional electrocatalyst for efficient overall water splitting† †Electronic supplementary information (ESI) available: Experimental and computational details and additional data. See DOI: 10.1039/c7sc04569g

PubMed Central

Zhang, Fang-Shuai; Wang, Jia-Wei; Luo, Jun; Liu, Rui-Rui

2017-01-01

The development of highly efficient, low-cost and stable electrocatalysts for overall water splitting is highly desirable for the storage of intermittent solar energy and wind energy sources. Herein, we show for the first time that nickel can be extracted from NiFe-layered double hydroxide (NiFe-LDH) to generate an Ni2P@FePOx heterostructure. The Ni2P@FePOx heterostructure was converted to an Ni2P@NiFe hydroxide heterostructure (P-NiFe) during water splitting, which displays high electrocatalytic performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH solution, with an overpotential of 75 mV at 10 mA cm–2 for HER, and overpotentials of 205, 230 and 430 mV at 10, 100 and 1000 mA cm–2 for OER, respectively. Moreover, it could afford a stable current density of 10 mA cm–2 for overall water splitting at 1.51 V in 1.0 M KOH with long-term durability (100 h). This cell voltage is among the best reported values for bifunctional electrocatalysts. The results of theoretical calculations demonstrate that P-NiFe displays optimized adsorption energies for both HER and OER intermediates at the nickel active sites, thus dramatically enhancing its electrocatalytic activity. PMID:29675186

Sugar Blowing-Induced Porous Cobalt Phosphide/Nitrogen-Doped Carbon Nanostructures with Enhanced Electrochemical Oxidation Performance toward Water and Other Small Molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Chengzhou; Fu, Shaofang; Xu, Bo Z.

Finely controlled synthesis of high active and robust nonprecious metal catalysts with excellent catalytic efficiency in oxygen evolution reaction (OER) is extremely vital for making the water splitting process more energy-efficient and economical. Among these noble metal-free catalysts, transition-metal-based nanomaterials are considered as one of the most promising OER catalysts due to their relatively low-cost intrinsic activities, high abundance and diversity in terms of structure and morphology. In this work, we reported a facile sugar-blowing technique and low-temperature phosphorization to generate 3D self-supported metal involved carbon nanostructures, which termed as Co2P@Co/nitrogen-doped carbon (Co2P@Co/N-C). By capitalizing on the 3D porous nanostructuresmore » with high surface area, generously dispersed active sites, the intimate interaction between active sites and 3D N-doped carbon, the resultant Co2P@Co/N-C exhibited satisfying OER performance superior to CoO@Co/N-C, delivering 10 mA cm-2 at overpotential of 0.32 V. It is noting that in contrast to the substantial current density loss of RuO2, Co2P@Co/N-C showed much enhanced catalytic activity during the stability test and the 1.8-fold increase in current density was observed after stability test. Furthermore, the obtained Co2P@Co/N-C can also be served as an excellent nonprecious metal catalyst for methanol and glucose electrooxidation in alkaline media, further extending their potential applications.« less

Single-Site Active Iron-Based Bifunctional Oxygen Catalyst for a Compressible and Rechargeable Zinc-Air Battery.

PubMed

Ma, Longtao; Chen, Shengmei; Pei, Zengxia; Huang, Yan; Liang, Guojin; Mo, Funian; Yang, Qi; Su, Jun; Gao, Yihua; Zapien, Juan Antonio; Zhi, Chunyi

2018-02-27

The exploitation of a high-efficient, low-cost, and stable non-noble-metal-based catalyst with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) simultaneously, as air electrode material for a rechargeable zinc-air battery is significantly crucial. Meanwhile, the compressible flexibility of a battery is the prerequisite of wearable or/and portable electronics. Herein, we present a strategy via single-site dispersion of an Fe-N x species on a two-dimensional (2D) highly graphitic porous nitrogen-doped carbon layer to implement superior catalytic activity toward ORR/OER (with a half-wave potential of 0.86 V for ORR and an overpotential of 390 mV at 10 mA·cm -2 for OER) in an alkaline medium. Furthermore, an elastic polyacrylamide hydrogel based electrolyte with the capability to retain great elasticity even under a highly corrosive alkaline environment is utilized to develop a solid-state compressible and rechargeable zinc-air battery. The creatively developed battery has a low charge-discharge voltage gap (0.78 V at 5 mA·cm -2 ) and large power density (118 mW·cm -2 ). It could be compressed up to 54% strain and bent up to 90° without charge/discharge performance and output power degradation. Our results reveal that single-site dispersion of catalytic active sites on a porous support for a bifunctional oxygen catalyst as cathode integrating a specially designed elastic electrolyte is a feasible strategy for fabricating efficient compressible and rechargeable zinc-air batteries, which could enlighten the design and development of other functional electronic devices.

Les cooperatives et l'electrification rurale du Quebec, 1945--1964

NASA Astrophysics Data System (ADS)

Dorion, Marie-Josee

Cette these est consacree a l'histoire de l'electrification rurale du Quebec, et, plus particulierement, a l'histoire des cooperatives d'electricite. Fondees par vagues successives a partir de 1945, les cooperatives rurales d'electricite ont ete actives dans plusieurs regions du Quebec et elles ont electrifie une partie significative des zones rurales. Afin de comprendre le contexte de la creation des cooperatives d'electricite, notre these debute (premiere partie) par une analyse du climat sociopolitique des annees precedant la naissance du systeme cooperatif d'electrification rurale. Nous y voyons de quelle facon l'electrification rurale devient progressivement, a partir de la fin des annees 1920, une question d'actualite a laquelle les divers gouvernements qui se succedent tentent de trouver une solution, sans engager---ou si peu---les fonds de l'Etat. En ce sens, la premiere etatisation et la mise sur pied d'Hydro-Quebec, en 1944, marquent une rupture quant au mode d'action privilegie jusque-la. La nouvelle societe d'Etat se voit cependant retirer son mandat d'electrifier le monde rural un an apres sa fondation, car le gouvernement Duplessis, de retour au pouvoir, prefere mettre en place son propre modele d'electrification rurale. Ce systeme repose sur des cooperatives d'electricite, soutenues par un organisme public, l'Office de l'electrification rurale (OER). L'OER suscite de grandes attentes de la part des ruraux et c'est par centaines qu'ils se manifestent. Cet engouement pour les cooperatives complique la tache de l'OER, qui doit superviser de nouvelles societes tout en assurant sa propre organisation. Malgre des hesitations et quelques delais introduits par un manque de connaissances techniques et de personnel qualifie, les commissaires de l'OER se revelent perspicaces et parviennent a mettre sur pied un systeme cooperatif d'electrification rurale qui produit des resultats rapides. Il leur faudra cependant compter sur l'aide des autres acteurs engages dans l'electrification, les organismes publics et les compagnies privees d'electricite. Cette periode de demarrage et d'organisation, traitee dans la deuxieme partie de la these, se termine en 1947-48, au moment ou l'OER et les cooperatives raffermissent leur maitrise du systeme cooperatif d'electrification rurale. Les annees 1948 a 1955 (troisieme partie de these) correspondent a une periode de croissance pour le mouvement cooperatif. Cette partie scrute ainsi le developpement des cooperatives, les vastes chantiers de construction et l'injection de millions de dollars dans l'electrification rurale. Cette troisieme partie prend egalement acte des premiers signes que quelque chose ne va pas si bien dans le monde cooperatif. Nous y verrons egalement les ruraux a l'oeuvre: comme membres, d'abord, mais aussi en tant que benevoles, puis a l'emploi des cooperatives. La quatrieme et derniere partie, les annees 1956 a 1964, aborde les changements majeurs qui ont cours dans l'univers cooperatif; il s'agit d'une ere nouvelle et difficile pour le mouvement cooperatif, dont les reseaux paraissent inadaptes aux changements de profil de la consommation d'electricite des usagers. L'OER sent alors le besoin de raffermir son controle des cooperatives, car il pressent les problemes et les defis auxquels elles auront a faire face. Notre etude se termine par l'acquisition des cooperatives par Hydro-Quebec, en 1963-64. Fondee sur des sources riches et variees, notre demarche propose un eclairage inedit sur une dimension importante de l'histoire de l'electricite au Quebec. Elle permet, ce faisant, de saisir les rouages et l'action de l'Etat sous un angle particulier, avant sa profonde transformation amorcee au cours des annees 1960. De meme, elle apporte quelques cles nouvelles pour une meilleure comprehension de la dynamique des milieux ruraux de cette periode.

The Role of Ocean Exploration and Research in the Creation and Management of Marine Protected Areas (MPAs)

NASA Astrophysics Data System (ADS)

Valette-Silver, N. J.; Pomponi, S.; Smith, J. R.; Potter, J.

2012-12-01

Over the past decades, the NOAA Office of Ocean Exploration and Research (OER), through its programs (Ocean Exploration Program and National Undersea Research Program), and in collaboration with its federal and academic partners, has contributed to the discovery of new ocean features, species, ecosystems, habitats and processes. These new discoveries have led to the development of new policies and management actions. Exploration, research and technology advancement have contributed to the characterization and the designation of marine sanctuaries, reserves, restricted fishing areas, and monuments in US waters. For example, the collaborative efforts of OER and partners from the Cooperative Institute for Ocean Exploration, Research and Technology (CIOERT) have resulted in the discovery of new species of deep sea corals on the outer continental shelf and upper slope of the South Atlantic Bight. The species of coral found in these deep sea reefs are growing very slowly and provide habitat for many commercially valuable species of fish and other living resources. It is not yet completely clear how these habitats connect with the shallower reefs and habitats and if they could be playing a role of refugia for shallower species. Unfortunately, signs of fishing destruction on these unique and fragile habitats are obvious (e.g., abandoned nets, completely decimated habitats by trawling). OER funded research on mesophotic and deep-sea Lophelia coral reefs off the southeastern US was instrumental in the designation of the deep-water Coral Habitat Area of Particular Concern (CHAPC) that is now protecting these fragile reefs. Other examples of OER's contribution to discoveries leading to the designation of protected areas include the characterization and boundary determination of new designated Marine National Monuments and Marine Sanctuaries in the Pacific Ocean. After designation of a protected area, it is imperative to monitor the resource, improve understanding of its functioning, and thus be in a position to better protect it. While most of the reef fish surveys are conducted in shallow areas (0-20 m), it is recognized that many commercially exploited fish stocks also utilize deeper habitats (50-400m). However, traditional methods (e.g., hook-and-line) for sampling these bottom fish species cannot be used in many areas of the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve [now a Monument] and other restricted fishing areas. Our ability to assess and monitor ocean living marine resources is important for ecosystem management as well as for determining the effectiveness of Marine Protected Areas (MPAs). The development and deployment of non-extractive sampling methods such as autonomous camera systems to collect information about the spatial distribution and relative abundance of bottom fish species is one of the preferred methods. In addition, OER and the Hawaii Undersea Research Lab (HURL) were two of the first groups to conduct scientific research in the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve after it was established in 2000. Submersible dives (down to 2000 m) or ROV dives into the depths surrounding the remote islands, banks, and atolls have led to dozens of discoveries of new and yet to be identified species.

NOAA Office of Exploration and Research > Exploration > Systematic

Science.gov Websites

Exploration Systematic Exploration Marine Archaeology Ocean and Coastal Mapping Advancing Technology Overview Exploration Marine Archaeology Ocean and Coastal Mapping Exploration Systematic Exploration Home About OER Systematic Exploration Marine Archaeology Ocean and Coastal Mapping Advancing Technology Overview Technology

Guide to Canadian Aerospace Related Industries,

DTIC Science & Technology

1984-03-01

manufacturing per- North America If, is tnus PaissiOre !or PT toc Oer a- exle- sonnel depending upon the product aird customer require- sive range af t...the Brazilian government-owned telecommunications Patrol Frigate. company. The project known as Sistema Brasiliero de Telecomunicacoes por Satelite

A New Era of Multidisciplinary Expeditions: Recent Opportunities and Progress to Advance the Telepresence Paradigm

NASA Astrophysics Data System (ADS)

Cantwell, K. L.; Kennedy, B. R.; Malik, M.; Gray, L. M.; Elliott, K.; Lobecker, E.; Drewniak, J.; Reser, B.; Crum, E.; Lovalvo, D.

2016-02-01

Since it's commissioning in 2008, NOAA Ship Okeanos Explorer has used telepresence technology both as an outreach tool and as a new way to conduct interdisciplinary science expeditions. NOAA's Office of Ocean Exploration and Research (OER) has developed a set of collaboration tools and protocols to enable extensive shore-based participation. Telepresence offers unique advantages including access to a large pool of expertise on shore and flexibility to react to new discoveries as they occur. During early years, the telepresence experience was limited to Internet 2 enabled Exploration Command Centers, but with advent of improved bandwidth and new video transcoders, scientists from anywhere with an internet connection can participate in a telepresence expedition. Scientists have also capitalized on social media (Twitter, Facebook, Reddit etc.) by sharing discoveries to leverage the intellectual capital of scientists worldwide and engaging the general public in real-time. Aside from using telepresence to stream video off the ship, the high-bandwidth satellite connection allows for the transfer of large quantities of data in near real-time. This enables not only ship - shore data transfers, but can also support ship - ship collaborations as demonstrated during the 2015 and 2014 seasons where Okeanos worked directly with science teams onboard other vessels to share data and immediately follow up on features of interest, leading to additional discoveries. OER continues to expand its use of telepresence by experimenting with procedures to offload roles previously tied to the ship, such as data acquisition watch standers; prototyping tools for distributed user data analysis and video annotation; and incorporating in-situ sampling devices. OER has also developed improved tools to provide access to archived data to increase data distribution and facilitate additional discoveries post-expedition.

ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua

Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wamore » Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.« less

Influence of Binders and Solvents on Stability of Ru/RuOx Nanoparticles on ITO Nanocrystals as Li-O2 Battery Cathodes.

PubMed

Vankova, Svetoslava; Francia, Carlotta; Amici, Julia; Zeng, Juqin; Bodoardo, Silvia; Penazzi, Nerino; Collins, Gillian; Geaney, Hugh; O'Dwyer, Colm

2017-02-08

Fundamental research on Li-O 2 batteries remains critical, and the nature of the reactions and stability are paramount for realising the promise of the Li-O 2 system. We report that indium tin oxide (ITO) nanocrystals with supported 1-2 nm oxygen evolution reaction (OER) catalyst Ru/RuO x nanoparticles (NPs) demonstrate efficient OER processes, reduce the recharge overpotential of the cell significantly and maintain catalytic activity to promote a consistent cycling discharge potential in Li-O 2 cells even when the ITO support nanocrystals deteriorate from the very first cycle. The Ru/RuO x nanoparticles lower the charge overpotential compared with those for ITO and carbon-only cathodes and have the greatest effect in DMSO electrolytes with a solution-processable F-free carboxymethyl cellulose (CMC) binder (<3.5 V) instead of polyvinylidene fluoride (PVDF). The Ru/RuO x /ITO nanocrystalline materials in DMSO provide efficient Li 2 O 2 decomposition from within the cathode during cycling. We demonstrate that the ITO is actually unstable from the first cycle and is modified by chemical etching, but the Ru/RuO x NPs remain effective OER catalysts for Li 2 O 2 during cycling. The CMC binders avoid PVDF-based side-reactions and improve the cyclability. The deterioration of the ITO nanocrystals is mitigated significantly in cathodes with a CMC binder, and the cells show good cycle life. In mixed DMSO-EMITFSI [EMITFSI=1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide] ionic liquid electrolytes, the Ru/RuO x /ITO materials in Li-O 2 cells cycle very well and maintain a consistently very low charge overpotential of 0.5-0.8 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Copper(II) tungstate nanoflake array films: sacrificial template synthesis, hydrogen treatment, and their application as photoanodes in solar water splitting.

PubMed

Hu, Dianyi; Diao, Peng; Xu, Di; Xia, Mengyang; Gu, Yue; Wu, Qingyong; Li, Chao; Yang, Shubin

2016-03-21

We report the preparation of CuWO4 nanoflake (NF) array films by using a solid phase reaction method in which WO3 NFs were employed as sacrificial templates. The SEM, TEM and XRD results demonstrated that the obtained CuWO4 films possessed a network structure that was composed of single crystalline NFs intersected with each other. The CuWO4 NF films showed superior photoelectrochemical (PEC) activity to other CuWO4 photoanodes reported recently for the oxygen evolution reaction (OER). We attributed the high activity to the unique morphological and crystalline structure of the CuWO4 film, which enhanced the photoactivity by providing a large specific area, a short hole transport distance from the inside of CuWO4 to the CuWO4/solution interface, and a low grain boundary density. Hydrogen treatment by annealing the CuWO4 NF film in mixed gases of H2 and Ar could further enhance the photoactivity, as hydrogen treatment significantly increased the electron density of CuWO4 by generating oxygen vacancy in the lattice. The photocurrent density for OER obtained on the hydrogen-treated (H-treated) CuWO4 NF film is the largest ever reported on CuWO4 photoanodes in the literature. Moreover, the CuWO4 photoanodes exhibit good stability in weak alkaline solution, while the H-treated CuWO4 photoanodes exhibit acceptable stability. This work not only reveals the potential of CuWO4 as a photoanode material for solar water splitting but also shows that the construction of nanostructured CuWO4 photoanodes is a promising method to achieve high PEC activity toward OER.

Quaternary FeCoNiMn-Based Nanocarbon Electrocatalysts for Bifunctional Oxygen Reduction and Evolution: Promotional Role of Mn Doping in Stabilizing Carbon

DOE PAGES

Gupta, Shiva; Zhao, Shuai; Wang, Xiao Xia; ...

2017-10-31

The intrinsic instability of carbon largely limits its use for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a bifunctional catalyst in reversible fuel cells or water electrolyzers. In this paper, we discovered that Mn doping has a promotional role in stabilizing nanocarbon catalysts for the ORR/OER in alkaline media. Stable nanocarbon composites are derived from an inexpensive carbon/nitrogen precursor (i.e., dicyandiamide) and quaternary FeCoNiMn alloy via a template-free carbonization process. In addition to FeCoNiMn metal alloys/oxides, the carbon composites comprise substantial carbon tube forests growing on a thick and dense graphitic substrate. The dense carbon substratemore » with high degree of graphitization results from Mn doping, while active nitrogen-doped carbon tubes stem from FeCoNi. Catalyst structures and performance are greatly dependent on the doping content of Mn. Various accelerated stress tests (AST) and life tests verify the encouraging ORR/OER stability of the nanocarbon composite catalyst with optimal Mn doping. Extensive characterization before and after ASTs elucidates the mechanism of stability enhancement resulting from Mn doping, which is attributed to (i) hybrid carbon nanostructures with enhanced resistance to oxidation and (ii) the in situ formation of the β-MnO 2 and FeCoNi-based oxides capable of preventing carbon corrosion and promoting activity. Note that the improvement in stability due to Mn doping is accompanied by a slight activity loss due to a decrease in surface area. Finally, this work provides a strategy to stabilize carbon catalysts by appropriately integrating transition metals and engineering carbon structures.« less

Quaternary FeCoNiMn-Based Nanocarbon Electrocatalysts for Bifunctional Oxygen Reduction and Evolution: Promotional Role of Mn Doping in Stabilizing Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Shiva; Zhao, Shuai; Wang, Xiao Xia

The intrinsic instability of carbon largely limits its use for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a bifunctional catalyst in reversible fuel cells or water electrolyzers. In this paper, we discovered that Mn doping has a promotional role in stabilizing nanocarbon catalysts for the ORR/OER in alkaline media. Stable nanocarbon composites are derived from an inexpensive carbon/nitrogen precursor (i.e., dicyandiamide) and quaternary FeCoNiMn alloy via a template-free carbonization process. In addition to FeCoNiMn metal alloys/oxides, the carbon composites comprise substantial carbon tube forests growing on a thick and dense graphitic substrate. The dense carbon substratemore » with high degree of graphitization results from Mn doping, while active nitrogen-doped carbon tubes stem from FeCoNi. Catalyst structures and performance are greatly dependent on the doping content of Mn. Various accelerated stress tests (AST) and life tests verify the encouraging ORR/OER stability of the nanocarbon composite catalyst with optimal Mn doping. Extensive characterization before and after ASTs elucidates the mechanism of stability enhancement resulting from Mn doping, which is attributed to (i) hybrid carbon nanostructures with enhanced resistance to oxidation and (ii) the in situ formation of the β-MnO 2 and FeCoNi-based oxides capable of preventing carbon corrosion and promoting activity. Note that the improvement in stability due to Mn doping is accompanied by a slight activity loss due to a decrease in surface area. Finally, this work provides a strategy to stabilize carbon catalysts by appropriately integrating transition metals and engineering carbon structures.« less

Rochester Epidemiology Project Data Exploration Portal

PubMed Central

Grossardt, Brandon R.; Finney Rutten, Lila J.; Roger, Veronique L.; Majerus, Michelle; Jensen, Daniel W.; Brue, Scott M.; Bock-Goodner, Cynthia M.; Rocca, Walter A.

2018-01-01

Introduction The goal of this project was to develop an interactive, web-based tool to explore patterns of prevalence and co-occurrence of diseases using data from the expanded Rochester Epidemiology Project (E-REP) medical records-linkage system. Methods We designed the REP Data Exploration Portal (REP DEP) to include summary information for people who lived in a 27-county region of southern Minnesota and western Wisconsin on January 1, 2014 (n = 694,506; 61% of the entire population). We obtained diagnostic codes of the International Classification of Diseases, 9th edition, from the medical records-linkage system in 2009 through 2013 (5 years) and grouped them into 717 disease categories. For each condition or combination of 2 conditions (dyad), we calculated prevalence by dividing the number of persons with a specified condition (numerator) by the total number of persons in the population (denominator). We calculated observed-to-expected ratios (OERs) to test whether 2 conditions co-occur more frequently than would co-occur as a result of chance alone. Results We launched the first version of the REP DEP in May 2017. The REP DEP can be accessed at http://rochesterproject.org/portal/. Users can select 2 conditions of interest, and the REP DEP displays the overall prevalence, age-specific prevalence, and sex-specific prevalence for each condition and dyad. Also displayed are OERs overall and by age and sex and maps of county-specific prevalence of each condition and OER. Conclusion The REP DEP draws upon a medical records-linkage system to provide an innovative, rapid, interactive, free-of-charge method to examine the prevalence and co-occurrence of 717 diseases and conditions in a geographically defined population. PMID:29654640

The Trouble with Textbooks

ERIC Educational Resources Information Center

Frederiksen, Linda

2013-01-01

Proponents of Open Educational Resources (OER) point to numerous ways that a new approach to thinking about teaching and learning can break down barriers, making education accessible, available, and affordable to all. Digitized educational material that can be used, reused, translated, customized, and shared by faculty, students, and researchers…

40 CFR 1.45 - Office of Research and Development.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the fate, transport, and environmental levels which may result in human exposure and exposure of nonhuman components of the environment, resulting from the discharge of pollutants, singly or in...; managing grant projects; and ensuring project quality and optimum dissemination of results. The OER is...

40 CFR 1.45 - Office of Research and Development.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the fate, transport, and environmental levels which may result in human exposure and exposure of nonhuman components of the environment, resulting from the discharge of pollutants, singly or in...; managing grant projects; and ensuring project quality and optimum dissemination of results. The OER is...

40 CFR 1.45 - Office of Research and Development.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the fate, transport, and environmental levels which may result in human exposure and exposure of nonhuman components of the environment, resulting from the discharge of pollutants, singly or in...; managing grant projects; and ensuring project quality and optimum dissemination of results. The OER is...

40 CFR 1.45 - Office of Research and Development.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the fate, transport, and environmental levels which may result in human exposure and exposure of nonhuman components of the environment, resulting from the discharge of pollutants, singly or in...; managing grant projects; and ensuring project quality and optimum dissemination of results. The OER is...

40 CFR 1.45 - Office of Research and Development.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the fate, transport, and environmental levels which may result in human exposure and exposure of nonhuman components of the environment, resulting from the discharge of pollutants, singly or in...; managing grant projects; and ensuring project quality and optimum dissemination of results. The OER is...

Si photoanode protected by a metal modified ITO layer with ultrathin NiO(x) for solar water oxidation.

PubMed

Sun, Ke; Shen, Shaohua; Cheung, Justin S; Pang, Xiaolu; Park, Namseok; Zhou, Jigang; Hu, Yongfeng; Sun, Zhelin; Noh, Sun Young; Riley, Conor T; Yu, Paul K L; Jin, Sungho; Wang, Deli

2014-03-14

We report an ultrathin NiOx catalyzed Si np(+) junction photoanode for a stable and efficient solar driven oxygen evolution reaction (OER) in water. A stable semi-transparent ITO/Au/ITO hole conducting oxide layer, sandwiched between the OER catalyst and the Si photoanode, is used to protect the Si from corrosion in an alkaline working environment, enhance the hole transportation, and provide a pre-activation contact to the NiOx catalyst. The NiOx catalyzed Si photoanode generates a photocurrent of 1.98 mA cm(-2) at the equilibrium water oxidation potential (EOER = 0.415 V vs. NHE in 1 M NaOH solution). A thermodynamic solar-to-oxygen conversion efficiency (SOCE) of 0.07% under 0.51-sun illumination is observed. The successful development of a low cost, highly efficient, and stable photoelectrochemical electrode based on earth abundant elements is essential for the realization of a large-scale practical solar fuel conversion.

Surface Engineering of a Nickel Oxide-Nickel Hybrid Nanoarray as a Versatile Catalyst for Both Superior Water and Urea Oxidation.

PubMed

Yue, Zhihao; Zhu, Wenxin; Li, Yuanzhen; Wei, Ziyi; Hu, Na; Suo, Yourui; Wang, Jianlong

2018-04-16

Developing efficient and low-cost oxygen evolution reaction (OER) electrodes is a pressing but still challenging task for energy conversion technologies such as water electrolysis, regenerative fuel cells, and rechargeable metal-air batteries. Hence, this study reports that a nickel oxide-nickel hybrid nanoarray on nickel foam (NiO-Ni/NF) could act as a versatile anode for superior water and urea oxidation. Impressively, this anode could attain high current densities of 50 and 100 mA cm -2 at extremely low overpotentials of 292 and 323 mV for OER, respectively. Besides, this electrode also shows excellent activity for urea oxidation with the need for just 0.28 and 0.36 V (vs SCE) to attain 10 and 100 mA cm -2 in 1.0 M KOH with 0.33 M urea, respectively. The enhanced oxidation performance should be due to the synergistic effect of NiO and Ni, improved conductivity, and enlarged active surface area.

Role of strain and conductivity in oxygen electrocatalysis on LaCoO3 thin films

DOE PAGES

Stoerzinger, Kelsey; Choi, Woo Seok; Jeen, Hyoung Jeen; ...

2015-01-19

The slow kinetics of the oxygen reduction and evolution reactions (ORR, OER) hinder energy conversion and storage in alkaline fuel cells and electrolyzers employing abundant transition metal oxide catalysts. Systematic studies linking material properties to catalytic activity are lacking, in part due to the heterogeneous nature of powder-based electrodes. We demonstrate, for the first time, that epitaxial strain can tune the activity of oxygen electrocatalysis in alkaline solutions, focusing on the model chemistry of LaCoO 3, where moderate tensile strain can further induce changes in the electronic structure via spin state to increase activity. The resultant decrease in charge transfermore » resistance to the electrolyte reduces the overpotential in the ORR more notably than the OER and suggests a different dependence of the respective rate-limiting steps on electron transfer. This provides new insight into the reaction mechanism applicable to a range of perovskite chemistries, key to the rational design of highly active catalysts.« less

One-step electrochemical deposition of Schiff base cobalt complex as effective water oxidation catalyst

NASA Astrophysics Data System (ADS)

Huang, Binbin; Wang, Yan; Zhan, Shuzhong; Ye, Jianshan

2017-02-01

Schiff base metal complexes have been applied in many fields, especially, a potential homogeneous catalyst for water splitting. However, the high overpotential, time consumed synthesis process and complicated working condition largely limit their application. In the present work, a one-step approach to fabricate Schiff base cobalt complex modified electrode is developed. Microrod clusters (MRC) and rough spherical particles (RSP) can be obtained on the ITO electrode through different electrochemical deposition condition. Both of the MRC and RSP present favorable activity for oxygen evolution reaction (OER) compared to the commercial Co3O4, taking an overpotential of 650 mV and 450 mV to drive appreciable catalytic current respectively. The highly active and stable RSP shows a Tafel plot of 84 mV dec-1 and negligible decrease of the current density for 12 h bulk electrolysis. The synthesis strategy of effective and stable catalyst in this work provide a simple method to fabricate heterogeneous OER catalyst with Schiff base metal complex.

Functional Independent Scaling Relation for ORR/OER Catalysts

DOE PAGES

Christensen, Rune; Hansen, Heine A.; Dickens, Colin F.; ...

2016-10-11

A widely used adsorption energy scaling relation between OH* and OOH* intermediates in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), has previously been determined using density functional theory and shown to dictate a minimum thermodynamic overpotential for both reactions. Here, we show that the oxygen–oxygen bond in the OOH* intermediate is, however, not well described with the previously used class of exchange-correlation functionals. By quantifying and correcting the systematic error, an improved description of gaseous peroxide species versus experimental data and a reduction in calculational uncertainty is obtained. For adsorbates, we find that the systematic error largelymore » cancels the vdW interaction missing in the original determination of the scaling relation. An improved scaling relation, which is fully independent of the applied exchange–correlation functional, is obtained and found to differ by 0.1 eV from the original. Lastly, this largely confirms that, although obtained with a method suffering from systematic errors, the previously obtained scaling relation is applicable for predictions of catalytic activity.« less

The development of a new methodology for knowledge sharing in the interface between university and society--an example from the meat sector.

PubMed

Algers, Anne; Silva-Fletcher, Ayona; Gregory, Neville; Hunt, Melvin

2013-11-01

Design science research was used for the generation, use and evaluation of a model for knowledge sharing in the user community through open educational resources (OER). The focus of interest was on the development process of a model for knowledge sharing that emphasizes the characteristics and the needs of the user community; the empowerment and democratic issues of openness; the collaboration between institutions and dialog with society; and the consideration of quality and sustainability issues. Initially, the community needs were analyzed through surveys and workshops, and the findings used, through negotiations, to formulate the development process. An open-training platform served as an infrastructure and included a repository with OER, a wiki and a discussion forum. The purpose of this article is an attempt to provide universities with a plan and template for integrated knowledge sharing that responds to societal needs. Usability and usefulness has not been evaluated. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multi-component Fe–Ni hydroxide nanocatalyst for oxygen evolution and methanol oxidation reactions under alkaline conditions

DOE PAGES

Candelaria, Stephanie L.; Bedford, Nicholas M.; Woehl, Taylor J.; ...

2016-11-29

Here, iron-incorporated nickel-based materials show promise as catalysts for the oxygen evolution reac-tion (OER) half-reaction of water electrolysis. Nickel has also exhibited high catalytic activity for methanol oxidation, particularly when in the form of a bimetallic catalyst. In this work, bimetallic iron-nickel nanoparticles were synthesized using a multi-step procedure in water under ambient conditions. When compared to monometallic iron and nickel nanoparticles, Fe-Ni nanoparticles show enhanced catalytic activity for both OER and methanol oxidation under alkaline conditions. At 1 mA/cm 2, the overpotential for monometallic iron and nickel nanoparticles was 421 mV and 476 mV, respectively, while the bimetallic Fe-Nimore » nanoparticles had a greatly reduced overpotential of 256 mV. At 10 mA/cm 2, bimetallic Fe-Ni nanoparticles had an overpotential of 311 mV. Spec-troscopy characterization suggests that the primary phase of nickel in Fe-Ni nanoparticles is the more disordered alpha phase of nickel hydroxide.« less

Electrocatalytic performances of g-C3N4-LaNiO3 composite as bi-functional catalysts for lithium-oxygen batteries

PubMed Central

Wu, Yixin; Wang, Taohuan; Zhang, Yidie; Xin, Sen; He, Xiaojun; Zhang, Dawei; Shui, Jianglan

2016-01-01

A low cost and non-precious metal composite material g-C3N4-LaNiO3 (CNL) was synthesized as a bifunctional electrocatalyst for the air electrode of lithium-oxygen (Li-O2) batteries. The composition strategy changed the electron structure of LaNiO3 and g-C3N4, ensures high Ni3+/Ni2+ ratio and more absorbed hydroxyl on the surface of CNL that can promote the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The composite catalyst presents higher activities than the individual components g-C3N4 and LaNiO3 for both ORR and OER. In non-aqueous Li-O2 batteries, CNL shows higher capacity, lower overpotentials and better cycling stability than XC-72 carbon and LaNiO3 catalysts. Our results suggest that CNL composite is a promising cathode catalyst for Li-O2 batteries. PMID:27074882

Chemical dynamics of the first proton-coupled electron transfer of water oxidation on TiO2 anatase.

PubMed

Chen, Jia; Li, Ye-Fei; Sit, Patrick; Selloni, Annabella

2013-12-18

Titanium dioxide (TiO2) is a prototype, water-splitting (photo)catalyst, but its performance is limited by the large overpotential for the oxygen evolution reaction (OER). We report here a first-principles density functional theory study of the chemical dynamics of the first proton-coupled electron transfer (PCET), which is considered responsible for the large OER overpotential on TiO2. We use a periodic model of the TiO2/water interface that includes a slab of anatase TiO2 and explicit water molecules, sample the solvent configurations by first principles molecular dynamics, and determine the energy profiles of the two electronic states involved in the electron transfer (ET) by hybrid functional calculations. Our results suggest that the first PCET is sequential, with the ET following the proton transfer. The ET occurs via an inner sphere process, which is facilitated by a state in which one electronic hole is shared by the two oxygen ions involved in the transfer.

Amorphous cobalt potassium phosphate microclusters as efficient photoelectrochemical water oxidation catalyst

NASA Astrophysics Data System (ADS)

Zhang, Ye; Zhao, Chunsong; Dai, Xuezeng; Lin, Hong; Cui, Bai; Li, Jianbao

2013-12-01

A novel amorphous cobalt potassium phosphate hydrate compound (KCoPO4·H2O) is identified to be active photocatalyst for oxygen evolution reaction (OER) to facilitate hydrogen generation from water photolysis. It has been synthesized through a facile and cost-effective solution-based precipitation method using earth-abundant materials. Its highly porous structure and large surface areas are found to be responsible for the excellent electrochemical performance featuring a low OER onset at ∼550 mVSCE and high current density in alkaline condition. Unlike traditional cobalt-based spinel oxides (Co3O4, NiCo2O4) and phosphate (Co-Pi, Co(PO3)2) electrocatalysts, with proper energy band alignment for light-assisted water oxidation, cobalt potassium phosphate hydrate also exhibits robust visible-light response, generating a photocurrent density of ∼200 μA cm-2 at 0.7 VSCE. This catalyst could thus be considered as a promising candidate to perform photoelectrochemical water splitting.

Assessing the Potential toward Open Educational Practices in Kyrgyzstan

ERIC Educational Resources Information Center

Walz, Anita R.; Bekbalaeva, Jyldyz

2018-01-01

The study was undertaken to understand the propensity for increased engagement with open educational practices (OEP), to include methods prioritizing student-centered teaching & learning, and awareness, use, and development of open educational resources (OER) among higher education faculty in Kyrgyzstan. The study employed a mixed-methods…

Positioning the OER Business Model for Open Education

ERIC Educational Resources Information Center

de Langen, F. H. T.; Bitter-Rijkema, M. E.

2012-01-01

The enabling power of technology, especially information technology and social software, prompts a radical shift in economic and social interactions in societies around the globe. Existing traditional school based, formalized learning formats are unable to accommodate specific new learning needs. Hence, customized to the respective purposes of…

LCTLs and Technology: The Promise of Open Education

ERIC Educational Resources Information Center

Blyth, Carl

2013-01-01

LCTL educators are beginning to participate in the Open Education movement by developing and sharing their own pedagogical materials referred to as open educational resources (OERs). This new generation of collaborative LCTL materials will invariably challenge longstanding hegemonies in the fields of foreign language education and educational…

Clarifying the Controversial Catalytic Performance of Co(OH)2 and Co3O4 for Oxygen Reduction/Evolution Reactions toward Efficient Zn-Air Batteries.

PubMed

Song, Zhishuang; Han, Xiaopeng; Deng, Yida; Zhao, Naiqin; Hu, Wenbin; Zhong, Cheng

2017-07-12

Cobalt-based nanomaterials have been widely studied as catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to their remarkable bifunctional catalytic activity, low cost, and easy availability. However, controversial results concerning OER/ORR performance exist between different types of cobalt-based catalysts, especially for Co(OH) 2 and Co 3 O 4 . To address this issue, we develop a facile electrochemical deposition method to grow Co(OH) 2 directly on the skeleton of carbon cloth, and further Co 3 O 4 was obtained by post thermal treatment. The entire synthesis strategy removes the use of any binders and also avoids the additional preparation process (e.g., transfer and slurry coating) of final electrodes. This leads to a true comparison of the ORR/OER catalytic performance between Co(OH) 2 and Co 3 O 4 , eliminating uncertainties arising from the electrode preparation procedures. The surface morphologies, microstructures, and electrochemical behaviors of prepared Co(OH) 2 and Co 3 O 4 catalysts were systemically investigated by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and electrochemical characterization methods. The results revealed that the electrochemically deposited Co(OH) 2 was in the form of vertically aligned nanosheets with average thickness of about 4.5 nm. After the thermal treatment in an air atmosphere, Co(OH) 2 nanosheets were converted into mesoporous Co 3 O 4 nanosheets with remarkably increased electrochemical active surface area (ECSA). Although the ORR/OER activity normalized by the geometric surface area of mesoporous Co 3 O 4 nanosheets is higher than that of Co(OH) 2 nanosheets, the performance normalized by the ECSA of the former is lower than that of the latter. Considering the superior apparent overall activity and durability, the Co 3 O 4 catalyst has been further evaluated by integrating it into a Zn-air battery prototype. The Co 3 O 4 nanosheets in situ supported on carbon cloth cathode enable the assembled Zn-air cells with large peak power density of 106.6 mW cm -2 , low charge and discharge overpotentials (0.67 V), high discharge rate capability (1.18 V at 20 mA cm -2 ), and long cycling stability (400 cycles), which are comparable or even superior to the mixture of state-of-the-art Pt/C and RuO 2 cathode.

SISGR-Fundamental Experimental and Theoretical Studies on a Novel Family of Oxide Catalyst Supports for Water Electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumta, Prashant

2014-10-03

Identification and development of non-noble metal based electro-catalysts or electro-catalysts with significant reduction of expensive noble metal contents (E.g. IrO2, Pt) with comparable electrochemical performance as the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would constitute a major breakthrough in the generation of hydrogen by water electrolysis. Accomplishing such a system would not only result reduction of the overall capital costs of PEM based water electrolyzers, but also help attain the targeted hydrogen production cost [< $ 3.0 / gallon gasoline equivalent (gge)] comparable to conventional liquid fuels. In line with these goals, it wasmore » demonstrated that fluorine doped IrO2 thin films and nanostructured high surface area powders display remarkably higher electrochemical activity, and comparable durability as pure IrO2 electro-catalyst for the oxygen evolution reaction (OER) in PEM based water electrolysis. Furthermore, corrosion resistant SnO2 and NbO2 support has been doped with F and coupled with IrO2 or RuO2 for use as an OER electro-catalyst. A solid solution of SnO2:F or NbO2:F with only 20 - 30 mol.% IrO2 or RuO2 yielding a rutile structure in the form of thin films and bulk nanoparticles displays similar electrochemical activity and stability as pure IrO2/RuO2. This would lead to more than 70 mol.% reduction in the noble metal oxide content. Novel nanostructured ternary (Ir,Sn,Nb)O2 thin films of different compositions FUNDAMENTAL STUDY OF NANOSTRUCTURED ELECTRO-CATALYSTS WITH REDUCED NOBLE METAL CONTENT FOR PEM BASED WATER ELECTROLYSIS 4 have also been studied. It has been shown that (Ir0.40Sn0.30Nb0.30)O2 shows similar electrochemical activity and enhanced chemical robustness as compared to pure IrO2. F doping of the ternary (Ir,Sn,Nb)O2 catalyst helps in further decreasing the noble metal oxide content of the catalyst. As a result, these reduced noble metal oxide catalyst systems would potentially be preferred as OER electro-catalysts for PEM electrolysis. The excellent performance of the catalysts coupled with its robustness would make them great candidates for contributing to significant reduction in the overall capital costs of PEM based water electrolyzers. This s.thesis provides a detailed fundamental study of the synthesis, materials, characterization, theoretical studies and detailed electrochemical response and potential mechanisms of these novel electro-catalysts for OER processes.« less

Sharing Resources in Open Educational Communities

ERIC Educational Resources Information Center

Tosato, Paolo; Arranz, Beatriz Carramolino; Avi, Bartolomé Rubia

2014-01-01

The spread of Internet and the latest Web developments have promoted the relationships between teachers, learners and institutions, as well as the creation and sharing of new Open Educational Resources (OERs). Despite this fact, many projects and research efforts paid more attention to content distribution focusing on their format and description,…

NOAA Office of Exploration and Research > Data Access > Overview

Science.gov Websites

Management of Environmental Data and Information and related Procedural Directives inform OER INFORMATION ON THE NOAA OFFICE OF OCEAN EXPLORATION AND RESEARCH, VISIT: OCEANEXPLORER.NOAA.GOV weather oceans Science Overview Data Access Overview Operational Data Management Publications Education Overview Alliance

Investigating an Open Methodology for Designing Domain-Specific Language Collections

ERIC Educational Resources Information Center

Fitzgerald, Alannah; Wu, Shaoqun; Barge, Martin

2014-01-01

With this research and design paper, we are proposing that Open Educational Resources (OERs) and Open Access (OA) publications give increasing access to high quality online educational and research content for the development of powerful domain-specific language collections that can be further enhanced linguistically with the Flexible Language…

Open Educational Resources for Call Teacher Education: The iTILT Interactive Whiteboard Project

ERIC Educational Resources Information Center

Whyte, Shona; Schmid, Euline Cutrim; van Hazebrouck Thompson, Sanderin; Oberhofer, Margret

2014-01-01

This paper discusses challenges and opportunities arising during the development of open educational resources (OERs) to support communicative language teaching (CLT) with interactive whiteboards (IWBs). iTILT (interactive Technologies in Language Teaching), a European Lifelong Learning Project, has two main aims: (a) to promote "best…

The Infrastructure of Open Educational Resources

ERIC Educational Resources Information Center

Smith, Marshall S.; Wang, Phoenix M.

2007-01-01

The success of OER is likely to depend on a flexible, extendable infrastructure that will meet the challenges of an evolving World Wide Web. In this article, the authors examine three key dimensions of this infrastructure--technical, legal/cultural/social/political, and research--and discuss possible directions for development. (Contains 1 table…

Rethinking OER and Their Use: Open Education as Bildung

ERIC Educational Resources Information Center

Deimann, Markus; Farrow, Robert

2013-01-01

Despite the recent increases of interest in open education, notably in massive open online courses (MOOCs) (Fini, 2009), it has been continuously asserted that this form of social knowledge production lacks a philosophical or theoretical foundation (Vandenberg, 1975). Similar accusations have been made with respect to distance education, such as…

Integration of Open Educational Resources in Undergraduate Chemistry Teaching--A Mapping Tool and Lecturers' Considerations

ERIC Educational Resources Information Center

Feldman-Maggor, Yael; Rom, Amira; Tuvi-Arad, Inbal

2016-01-01

This study examines chemistry lecturers' considerations for using open educational resources (OER) in their teaching. Recent technological developments provide innovative approaches for teaching chemistry and visualizing chemical phenomena. End users' improved ability to upload information online enables integration of various pedagogical models…

Identifying Tensions in the Use of Open Licenses in OER Repositories

ERIC Educational Resources Information Center

Amiel, Tel; Soares, Tiago Chagas

2016-01-01

We present an analysis of 50 repositories for educational content conducted through an "audit system" that helped us classify these repositories, their software systems, promoters, and how they communicated their licensing practices. We randomly accessed five resources from each repository to investigate the alignment of licensing…

NOAA Office of Exploration and Research > Exploration > Ocean and Coastal

Science.gov Websites

Exploration Systematic Exploration Marine Archaeology Ocean and Coastal Mapping Advancing Technology Overview Exploration Marine Archaeology Ocean and Coastal Mapping Exploration Ocean and Coastal Mapping Home About OER Systematic Exploration Marine Archaeology Ocean and Coastal Mapping Advancing Technology Overview Technology

Generating OER by Recording Lectures: A Case Study

ERIC Educational Resources Information Center

Llamas-Nistal, Martín; Mikic-Fonte, Fernando A.

2014-01-01

The University of Vigo, Vigo, Spain, has the objective of making all the teaching material generated by its teachers freely available. To attain this objective, it encourages the development of Open Educational Resources, especially videos. This paper presents an experience of recording lectures and generating the corresponding videos as a step…

Open Educational Resources: Staff Attitudes and Awareness

ERIC Educational Resources Information Center

Rolfe, Vivien

2012-01-01

Attitudes are changing in education globally to promote the open sharing of educational courses and resources. The aim of this study was to explore staff awareness and attitudes towards "open educational resources" (OER) as a benchmark for monitoring future progress. Faculty staff (n = 6) were invited to participate in semi-structured…

Digital Divide in Post-Primary Schools

ERIC Educational Resources Information Center

Marcus-Quinn, Ann; McGarr, Oliver

2013-01-01

This research study developed curricular specific open educational resources (OERs) for the teaching of poetry at Junior Certificate level in Irish post-primary schools. It aimed to capture the collaborative design and development process used in the development of the digital resources and describe and evaluate the implementation of the resources…

NOAA Office of Exploration and Research > Education > NOAA Initiatives

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Evaluation Education NOAA Initiatives Home About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan 2014 Funding Opportunities Contact Us Program

NOAA Office of Exploration and Research > Education > Alliance Partners

Science.gov Websites

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Evaluation Education Alliance Partners Home About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan 2014 Funding Opportunities Contact Us Program

OER "Produsage" as a Model to Support Language Teaching and Learning

ERIC Educational Resources Information Center

MacKinnon, Teresa; Pasfield-Neofitou, Sarah

2016-01-01

Language education faculty face myriad challenges in finding teaching resources that are suitable, of high quality, and allow for the modifications needed to meet the requirements of their course contexts and their learners. The article elaborates the grassroots model of "produsage" (a portmanteau of "production" and…

Environmental Technology Verification Report for Applikon MARGA Semi-Continuous Ambient Air Monitoring System

EPA Science Inventory

The verification test was conducted oer a period of 30 days (October 1 to October 31, 2008) and involved the continuous operation of duplicate semi-continuous monitoring technologies at the Burdens Creek Air Monitoring Site, an existing ambient-air monitoring station located near...

78 FR 25717 - Applications for New Awards; Strengthening Institutions Program (SIP)

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-02

... use of time, staff, money, or other resources while improving student learning or other educational... migrant, or who have disabilities. Open educational resources (OER) means teaching, learning, and research... awards for individual development grants in rank order from the funding slate according to the average...

Facile synthesis of electrospun MFe2O4 (M = Co, Ni, Cu, Mn) spinel nanofibers with excellent electrocatalytic properties for oxygen evolution and hydrogen peroxide reduction

NASA Astrophysics Data System (ADS)

Li, Mian; Xiong, Yueping; Liu, Xiaotian; Bo, Xiangjie; Zhang, Yufan; Han, Ce; Guo, Liping

2015-05-01

Designing and preparing porous transition metal ferrites without using any template, shape-directing agent, and surfactant is a challenge. Herein, heterojunction MFe2O4 (M = Co, Ni, Cu, Mn) nanofiber (NF) based films with three-dimensional configurations were synthesized by electrospinning and the subsequent thermal treatment processes. Characterization results indeed show the 3D net-like textural structures of the electrospun spinel-type MFe2O4 NFs. In particular, the resulting MFe2O4 NFs have lengths up to several dozens of micrometers with an average diameter size of about 150 nm and possess abundant micro/meso/macropores on both the surface and within the films. The hierarchically porous structures and high surface areas of these MFe2O4 NFs (for example, the CoFe2O4 NFs possess a larger BET specific surface area (61.48 m2 g-1) than those of the CoFe2O4 NPs (5.93 m2 g-1)) can afford accessible transport channels for effectively decreasing the mass transport resistances, enhancing the electrical conductivity, and increasing the density and reactivity of the exposed catalytic active sites. All these advantages will be responsible for the better electrocatalytic performances of these MFe2O4 NFs compared with their structural isomers (i.e. the MFe2O4 NPs) for the oxygen evolution reaction (OER) and H2O2 reduction in alkaline solution. Meanwhile, both the OER and H2O2 reduction catalytic activities for these MFe2O4 NFs obey the order of CoFe2O4 NFs > CuFe2O4 NFs > NiFe2O4 NFs > MnFe2O4 NFs > Fe2O3 NFs. The CoFe2O4 NFs represent a new class of highly efficient non-noble-metal catalysts for both OER and H2O2 reduction/detection in alkaline media.Designing and preparing porous transition metal ferrites without using any template, shape-directing agent, and surfactant is a challenge. Herein, heterojunction MFe2O4 (M = Co, Ni, Cu, Mn) nanofiber (NF) based films with three-dimensional configurations were synthesized by electrospinning and the subsequent thermal treatment processes. Characterization results indeed show the 3D net-like textural structures of the electrospun spinel-type MFe2O4 NFs. In particular, the resulting MFe2O4 NFs have lengths up to several dozens of micrometers with an average diameter size of about 150 nm and possess abundant micro/meso/macropores on both the surface and within the films. The hierarchically porous structures and high surface areas of these MFe2O4 NFs (for example, the CoFe2O4 NFs possess a larger BET specific surface area (61.48 m2 g-1) than those of the CoFe2O4 NPs (5.93 m2 g-1)) can afford accessible transport channels for effectively decreasing the mass transport resistances, enhancing the electrical conductivity, and increasing the density and reactivity of the exposed catalytic active sites. All these advantages will be responsible for the better electrocatalytic performances of these MFe2O4 NFs compared with their structural isomers (i.e. the MFe2O4 NPs) for the oxygen evolution reaction (OER) and H2O2 reduction in alkaline solution. Meanwhile, both the OER and H2O2 reduction catalytic activities for these MFe2O4 NFs obey the order of CoFe2O4 NFs > CuFe2O4 NFs > NiFe2O4 NFs > MnFe2O4 NFs > Fe2O3 NFs. The CoFe2O4 NFs represent a new class of highly efficient non-noble-metal catalysts for both OER and H2O2 reduction/detection in alkaline media. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07243j

Structural implications for oxygen electrocatalysis in earthabundant transition metal oxides

NASA Astrophysics Data System (ADS)

Gardner, Graeme Patrick

Transition metal oxides and related nitrides/nitride-oxides represent a class of materials that have shown great promise as oxygen electrocatalysts to replace the otherwise non-scalable noble metal-based catalysts currently implemented in commercial technologies. That is, compounds in this class of materials have shown promise as electrocatalysts for both the oxygen evolution (OER) and oxygen reduction reactions (ORR). The two aforementioned half-reactions are at the cornerstone of most renewable energy transformations, as oxygen is an inherently practical and abundant source and sink for electrons. In water electrolysis to produce hydrogen, oxygen is inevitably formed, and in a fuel cell the driving force for extracting electrochemical energy from hydrogen is pairing it with the reduction of oxygen to water. If this can be accomplished reversibly, the problem of "transient" renewable energy and its storage can be mitigated. We have examined many metal oxides and related compounds based upon Earth- abundant transition metals (primarily first row) that are crystalline, yet high surface area, for these important electrocatalytic reactions, and found that crystal structure plays a crucial role in determining activity. In fact, while most studies on heterogeneous catalysis focus on the synthesis of defect-rich, high surface area, practically amorphous materials to elicit high activity, we have found that particular crystalline phases possess not only the appropriate activity, but to some degree more importantly, the stability to be named good catalysts. In Chapter 2, we demonstrate that of the two structural types of lithium cobalt oxide (LiCoO2) - layered (R-3m) and cubic (Fd-3m) - only the cubic phase is revealed to be an efficient and stable catalyst for OER. Whether water oxidation is driven photochemically, or electrochemically, the cubic phase LiCoO2 possessing a spinel-like structure (AB 2O4) with [Co4O4] subunits within the crystal is more active. It is seen that electrochemically, both the cubic and layered phases transform to the spinel LiCo2O4 at surface and subsurface levels. This coincides with partial delithiation that is more extensive in layered LiCoO2. It is revealed that the oxidation of CoMn3+ to Co4+ is accompanied by delithiation in aqueous electrolyte to form the active state of the LiCoO2 catalyst. The electronic properties of the cubic spinel allow for localization of electron holes at cubic core active sites to effect water oxidation, whereas holes are more extensively delocalized in layered LiCoO2 in concert with the Li+ deintercalation reaction. In Chapter 3, we investigate the influence of chemical composition on the catalytic water oxidation activity of Co-substituted spinel LiMn 2O4 and Mn-substituted cubic LiCoO2. We find that in the spinel LiMn2O4, CoMn3+ substitution occurs at the B-site for MnMn3+, and the solid solution limit for starts at 1:1 Co:Mn ratio, where Co begins to go into the A-site. The activity for OER increases with increasing Co, owing to the symmetrization of the M4O4 core structure (Jahn-Teller distortions suppressed), which allows for hole delocalization that enables CoMn 3+/4+ oxidation. The more positive redox potential of Co4+ makes for facile water oxidation. Substituting Mn for Co in cubic LiCoO2 allows for retention of MnMn3+, which has been correlated with water oxidation activity in many catalysts. The solid solution limit in this series is also near 1:1 at the B- site. However, the increase in Mn content corresponds to decreasing activity in both water oxidation and oxygen reduction, which correlates well with decreases in pre- catalytic oxidation and reduction peak yields. The results show replacement of CoMn 3+ with MnMn3+ effectively eliminates active sites. Therefore, MnMn3+ in this electronic and structural environment is not active, which agrees well with a recent literature report on corner- shared MnMn3+ octahedral being necessary to produce OER activity in Mn oxides. Finally, in chapter 4, bifunctional oxygen electrocatalysts are explored in depth with a series of cobalt-molybdenum oxides/nitrides. We demonstrate that CoMoN2, with relatively strong M-N interactions, has ideal electronic properties for ORR, and upon oxidation of the surface, yields an active OER catalyst. However, the surface oxidation is found to be irreversible and once oxidized, the activity for ORR significantly decreases. The surface both before and after catalysis was analyzed by XPS, which showed the suppression of Mo and N signals after exposure to OER conditions, meaning the active catalyst is a Co oxide of high valency (3/4+). The results from this study suggests truly reversible, bifunctional oxygen electrocatalysis may be obtained by designing a catalyst whose surface is only partly oxidized and/or can be reversibly reduced in the potential window relevant to OER and ORR.

Critical Spaces for Critical Times: Global Conversations in Literacy Research as an Open Professional Development and Practices Resource

ERIC Educational Resources Information Center

Albers, Peggy; Cho, A. Ram; Shin, Ji Hye; Pang, Myoung Eun; Angay-Crowder, Tuba; Jung, Jin Kyeong; Pace, Christi L.; Sena, Mandi; Turnbull, Sarah

2015-01-01

This paper reflects an OER (Open Educational Resources) critical literacy project, Global Conversations in Literacy Research (GCLR), (www.globalconversationsinliteracy.wordpress.com), now in its fourth year. GCLR annually hosts seven web seminars presented by internationally recognized literacy and education scholars. We outline key dimensions of…

Web Applications That Promote Learning Communities in Today's Online Classrooms

ERIC Educational Resources Information Center

Reigle, Rosemary R.

2015-01-01

The changing online learning environment requires that instructors depend less on the standard tools built into most educational learning platforms and turn their focus to use of Open Educational Resources (OERs) and free or low-cost commercial applications. These applications permit new and more efficient ways to build online learning communities…

Extending the Territory: From Open Educational Resources to Open Educational Practices

ERIC Educational Resources Information Center

Ehlers, Ulf-Daniel

2011-01-01

This article examines the findings of the recent OPAL report "Beyond OER: Shifting Focus from Resources to Practices". In doing so, it defines current understanding of open educational resources and open educational practices, and highlights the shift from open content to open practice. The article includes a framework for supporting…

OER Approach for Specific Student Groups in Hardware-Based Courses

ERIC Educational Resources Information Center

Ackovska, Nevena; Ristov, Sasko

2014-01-01

Hardware-based courses in computer science studies require much effort from both students and teachers. The most important part of students' learning is attending in person and actively working on laboratory exercises on hardware equipment. This paper deals with a specific group of students, those who are marginalized by not being able to…

Curriculum, Intellectual Property Rights and Open Educational Resources in British Universities--and Beyond

ERIC Educational Resources Information Center

Hawkridge, David; Armellini, Alejandro; Nikoi, Samuel; Rowlett, Tania; Witthaus, Gabi

2010-01-01

Is the curriculum in British universities being influenced by decisions about ownership of intellectual property rights (IPR) in "open educational resources" (OERs) that are available online under Creative Commons licenses, free of charge? This paper provides the context for, describes and analyses three significant examples in British…

Analyzing Historical Primary Source Open Educational Resources: A Blended Pedagogical Approach

ERIC Educational Resources Information Center

Oliver, Kevin M.; Purichia, Heather R.

2018-01-01

This qualitative case study addresses the need for pedagogical approaches to working with open educational resources (OER). Drawing on a mix of historical thinking heuristics and case analysis approaches, a blended pedagogical strategy and primary source database were designed to build student understanding of historical records with transfer of…

Harnessing OER to Develop Teachers: The Guyana Experience

ERIC Educational Resources Information Center

Butcher, Neil; Moore, Andrew; Hoosen, Sarah

2014-01-01

The Ministry of Education in Guyana has prioritised increasing the number of qualified teachers by providing opportunities to both pre- and in-service teachers to gain relevant qualifications. This paper describes the process used to redesign the teacher training curriculum in Guyana to achieve the goals of a newly-developed ICT Professional…

Understanding and Exploring Signature Pedagogies for TESOL Teacher Education

ERIC Educational Resources Information Center

Eaton, Sarah Elaine; Wagner, Santoi; Hirashiki, Jennifer; Ciancio, Julie

2018-01-01

Purpose: The purpose of this report is to elevate the collective understanding of what it means to be and become a TESOL professional and what differentiates "TESOLers" from other teachers. We have intentionally prepared this report as an Open Educational Resource (OER), so it can be freely shared with an international audience. Methods:…

Open Data as Open Educational Resources: Towards Transversal Skills and Global Citizenship

ERIC Educational Resources Information Center

Atenas, Javiera; Havemann, Leo; Priego, Ernesto

2015-01-01

Open Data is the name given to datasets which have been generated by international organisations, governments, NGOs and academic researchers, and made freely available online and openly-licensed. These datasets can be used by educators as Open Educational Resources (OER) to support different teaching and learning activities, allowing students to…

Towards Networked Knowledge: The Learning Registry, an Infrastructure for Sharing Online Learning Resources

ERIC Educational Resources Information Center

Lee, Ashley; Hobson, Joe; Bienkowski, Marie; Midgley, Steve; Currier, Sarah; Campbell, Lorna M.; Novoselova, Tatiana

2012-01-01

In this article, the authors describe an open-source, open-data digital infrastructure for sharing information about open educational resources (OERs) across disparate systems and platforms. The Learning Registry, which began as a project funded by the U.S. Departments of Education and Defense, currently has an active international community…

Open Educational Resources: A Bridge to Education in the Developing World

ERIC Educational Resources Information Center

Pereira, Mike

2007-01-01

Leveraging ICT to equalize access to education is critical in a world with over four billion poor people who have little access to formal education. Mainstreaming OER as a public good throughout the developing world could make an enormous contribution. The Development Gateway Foundation has established an online OER…

An Open and Scalable Learning Infrastructure for Food Safety

ERIC Educational Resources Information Center

Manouselis, Nikos; Thanopoulos, Charalampos; Vignare, Karen; Geith, Christine

2013-01-01

In the last several years, a variety of approaches and tools have been developed for giving access to open educational resources (OER) related to food safety, security, and food standards, as well to various targeted audiences (e.g., farmers, agronomists). The aim of this paper is to present a technology infrastructure currently in demonstration…

Fostering the Exploitation of Open Educational Resources

ERIC Educational Resources Information Center

Richter, Thomas; Veith, Patrick

2014-01-01

The central concept behind Open Educational Resources (OER) is opening up the access to educational resources for stakeholders who are not the usual target user group. This concept must be perceived as innovative because it describes a general economic and social paradigm shift: Education, which formerly was limited to a specific group of…

When Educational Resources Are Open

ERIC Educational Resources Information Center

Breck, Judy

2007-01-01

This article is a partial look at what the future of education might be if educational resources become open online. Intertwingularity is discussed as a general term for what OER will do online. Predictions about an open education future are based on nine quotations from books by popular writers about our networked age. When the network mechanisms…

Impact of OpenCourseWare Publication on Higher Education Participation and Student Recruitment

ERIC Educational Resources Information Center

Carson, Stephen; Kanchanaraksa, Sukon; Gooding, Ira; Mulder, Fred; Schuwer, Robert

2012-01-01

The free and open publication of course materials (OpenCourseWare or OCW) was initially undertaken by Massachusetts Institute of Technology (MIT) and other universities primarily to share educational resources among educators (Abelson, 2007). OCW, however, and more in general open educational resources (OER), have also provided well-documented…

Rubrics for Evaluating Open Education Resource (OER) Objects

ERIC Educational Resources Information Center

Achieve, Inc., 2011

2011-01-01

The rubrics presented in this report represent an evaluation system for objects found within Open Education Resources. An object could include images, applets, lessons, units, assessments and more. For the purpose of this evaluation, any component that can exist as a stand-alone qualifies as an object. The rubrics in this packet can be applied…

Temoa: An Open Educational Resources Portal to Seek, Investigate and Inquire

ERIC Educational Resources Information Center

Gómez-Zermeño, Marcela Georgina; de la Garza, Lorena Yadira Alemán

2015-01-01

Temoa is a distributor of knowledge that provides a multilingual public catalog of collections of Open Educational Resources (OER). Temoa seeks to support the educational community to find the resources and materials that meet their needs for teaching and learning, through a specialized search system and collaborative social tools. Temoa was…

"Digital Futures in Teacher Education": Exploring Open Approaches towards Digital Literacy

ERIC Educational Resources Information Center

Gruszczynska, Anna; Merchant, Guy; Pountney, Richard,

2013-01-01

This paper reports the findings of a project "Digital Futures in Teacher Education" (DeFT) undertaken as part of the third phase of the Joint Information Systems Committee (JISC) UK Open Educational Resources (OER) programme. It builds on previous work (Gruszczynska and Pountney, 2012, 2013) that has addressed attempts to embed OER…

Developing a User Oriented Design Methodology for Learning Activities Using Boundary Objects

ERIC Educational Resources Information Center

Fragou, ?lga; Kameas, Achilles

2013-01-01

International Standards in High and Open and Distance Education are used for developing Open Educational Resources (OERs). Current issues in e-learning community are the specification of learning chunks and the definition of describing designs for different units of learning (activities, units, courses) in a generic though expandable format.…

The Open Course Library: Using Open Educational Resources to Improve Community College Access

ERIC Educational Resources Information Center

Goodwin, Mary Ann Lund

2011-01-01

Community colleges are committed to meeting the educational needs of the communities they serve and they have increased access to higher education by offering new and innovative services to students often unable to attend traditional baccalaureate institutions. An innovation known as Open Educational Resources (OER) promises to make college more…

Atolls, Islands, and Archipelagos: The California OER Council and the New Landscape for Open Education in California

ERIC Educational Resources Information Center

Hanley, Lawrence Francis; Bonilla, Diego

2016-01-01

California's three public higher education systems (University of California, California State University, the California Community College System) enroll nearly 3 million undergraduate students and employ almost 100 thousand faculty. In 2012, the California State Legislature directed the three systems to create an online library of open…

Enhancing Teaching and Learning: Libraries and Open Educational Resources in the Classroom

ERIC Educational Resources Information Center

Davis, Erin; Cochran, Dory; Fagerheim, Britt; Thoms, Becky

2016-01-01

Academic libraries continually adjust services to adapt to the ever-changing landscape in higher education. In response to the broken textbook market, libraries are becoming actively involved in the open educational resources (OER) movement. Although there is not a formal program in place, librarians at Utah State University explored a…

Social Networking: A Collaborative Open Educational Resource

ERIC Educational Resources Information Center

Toetenel, Lisette

2014-01-01

Studies undertaken since the introduction of Web 2.0 have focussed mainly on open educational resources (OERs) such as email, blogging and virtual learning environments. No consistent efforts have been undertaken to study the use of social networking sites as a tool for learning in the second language classroom. This study examined the use of…

Making Academic OER Easy: Reflections on Technology and Openness at Oxford University

ERIC Educational Resources Information Center

Highton, Melissa; Fresen, Jill; Wild, Joanna

2011-01-01

Due to its stringent entry requirements, academic reputation and world ranking, Oxford University in the United Kingdom is perceived by some as being a closed, exclusive, and elitist institution. As learning technologists working in the institution, we have experienced an enthusiasm amongst academic colleagues for openness in publication and…

Open Educational Partnerships and Collective Learning

ERIC Educational Resources Information Center

Macintyre, Ronald

2013-01-01

At the Open University in Scotland "openness" is part of our sense of self; our engagement with Open Educational Resources and Practices (OER/OEP) seems obvious. In this paper we explore some of those obvious aspects and using our partnership with a third sector organisation explore some of the less apparent aspects of openness. In…

Open Distribution of Virtual Containers as a Key Framework for Open Educational Resources and STEAM Subjects

ERIC Educational Resources Information Center

Corbi, Alberto; Burgos, Daniel

2017-01-01

This paper presents how virtual containers enhance the implementation of STEAM (science, technology, engineering, arts, and math) subjects as Open Educational Resources (OER). The publication initially summarizes the limitations of delivering open rich learning contents and corresponding assignments to students in college level STEAM areas. The…

On the Role of Openness in Education: A Historical Reconstruction

ERIC Educational Resources Information Center

Peter, Sandra; Deimann, Markus

2013-01-01

In the context of education, "open(ness)" has become the watermark for a fast growing number of learning materials and associated platforms and practices from a variety of institutions and individuals. Open Educational Resources (OER), Massive Open Online Courses (MOOC), and more recently, initiatives such as Coursera are just some of…

Open Educational Resources (OER): Opportunities and Challenges for Indian Higher Education

ERIC Educational Resources Information Center

Dutta, Indrajeet

2016-01-01

Creation of knowledge workers holds key for success of a country. Unfortunately, many of the countries though having chain of human resources yet are unable to transform human resources to their advantage as they face multiple challenges like poverty, poor economy, poor infrastructure, limited access to education and inadequate technological…

Project Familia. Final Evaluation Report, 1993-94. OER Report.

ERIC Educational Resources Information Center

New York City Board of Education, Brooklyn, NY. Office of Educational Research.

Project Familia was an Elementary and Secondary Education Act Title VII project in its second year in 1993-94 in New York City. Project Familia served 77 children at 3 schools who were identified as limited English proficient, special education students in prekindergarten through fifth grade and their parents. The project provided after-school…

ASK-LDT 2.0: A Web-Based Graphical Tool for Authoring Learning Designs

ERIC Educational Resources Information Center

Zervas, Panagiotis; Fragkos, Konstantinos; Sampson, Demetrios G.

2013-01-01

During the last decade, Open Educational Resources (OERs) have gained increased attention for their potential to support open access, sharing and reuse of digital educational resources. Therefore, a large amount of digital educational resources have become available worldwide through web-based open access repositories which are referred to as…

The Limitations of Access Alone: Moving Towards Open Processes in Education Technology

ERIC Educational Resources Information Center

Knox, Jeremy

2013-01-01

"Openness" has emerged as one of the foremost themes in education, within which an open education movement has enthusiastically embraced digital technologies as the central means of participation and inclusion. Open Educational Resources (OERs) and Massive Open Online Courses (MOOCs) have surfaced at the forefront of this development,…

Understanding Motivational System in Open Learning: Learners' Engagement with a Traditional Chinese-Based Open Educational Resource System

ERIC Educational Resources Information Center

Huang, Wenhao David; Wu, Chorng-Guang

2017-01-01

Learning has embraced the "open" process in recent years, as many educational resources are made available for free online. Existing research, however, has not provided sufficient evidence to systematically improve open learning interactions and engagement in open educational resource (OER) systems. This deficiency presents two…

A Path Analysis of Educator Perceptions of Open Educational Resources Using the Technology Acceptance Model

ERIC Educational Resources Information Center

Kelly, Hope

2014-01-01

Open educational resources (OER) are making their way into a variety of educational contexts from formal lesson planning to just in time learning. Educators and training professionals have been recognized as an important audience for these materials. The concepts of "self-efficacy" and "outcome judgment" from social cognitive…

OOPS! A Miracle Created by Confucius

ERIC Educational Resources Information Center

Chang, Agnes; Chu, Lucifer

2007-01-01

The story is told of the conception and creation of OOPS (Opensource Opencourseware Prototype System), which is a massive, worldwide volunteer project that translates OER into Mandarin. The founder and leader, Lucifer Chu, describes how the project grew from his own solo translation work to over 2,400 volunteers in 22 countries. In 2005 and 2006…

A Framework for Open Textbooks Analytics System

ERIC Educational Resources Information Center

Prasad, Deepak; Totaram, Rajneel; Usagawa, Tsuyoshi

2016-01-01

In the last few years, open textbook development has picked up dramatically due both to the expense of commercially published textbooks and the increasing availability of high-quality OER alternatives. While this offers a tremendous benefit in terms of lowering student textbook costs, the question remains, to what extent (if any) do open textbooks…

Higher Education Faculty Perceptions of Open Textbook Adoption

ERIC Educational Resources Information Center

Jung, Eulho; Bauer, Christine; Heaps, Allan

2017-01-01

The high cost of tuition and textbooks can have a negative impact on potential students from lower socioeconomic backgrounds. Open Educational Resources (OER) offers students a way to save educational costs while utilizing high-quality open textbooks. Up until now, there have been few studies focused on a specific provider of open textbooks. This…

A Taxonomy of Massive Open Online Courses

ERIC Educational Resources Information Center

Pilli, Olga; Admiraal, Wilfried

2016-01-01

Massive Open Online Courses (MOOCs) as a new approach to distance education, which originated from the open education resources (OER) movement, are becoming widespread throughout the world. Over time, early versions of cMOOCs have undergone changes in terms of use, name and structure. In their short life, MOOCs have been categorized into different…

Government Support for Open Educational Resources: Policy, Funding, and Strategies

ERIC Educational Resources Information Center

Stacey, Paul

2013-01-01

Foundations like Hewlett, Mellon, and Gates provided start-up funding and support that nurtured the field of open educational resources (OER) from infancy to a robust early adolescence characterized by energy and idealism (Casserly & Smith, 2008). However, foundation grants typically focus on establishing exemplars and cannot be relied on for…

Exploring Open Educational Resources for College Algebra

ERIC Educational Resources Information Center

Chiorescu, Marcela

2017-01-01

It is estimated that the average student spends around 1200 USD on books and supplies every school year; thus, textbook affordability has become more and more of a challenge for students. Replacing traditionally expensive learning resources with open educational resources (OER) can have a great impact in the reduction of cost for post-secondary…

A Framework for the Ethics of Open Education

ERIC Educational Resources Information Center

Farrow, Robert

2016-01-01

What difference does openness make to the ethics of teaching and research? This paper approaches this question both from the perspective of research into the use of open educational resources (OER) in teaching and learning. An outline of the nature and importance of ethics in education research is provided before the basic principles of research…

75 FR 55585 - Proposed Collection; Comment Request; Generic Clearance for Surveys of Customers and Partners of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-13

... Request; Generic Clearance for Surveys of Customers and Partners of the Office of Extramural Research of... collection projects, the Office of Extramural Research (OER), the National Institutes of Health (NIH) will... and Partners of the Office of Extramural Research of the National Institutes of Health. Type of...

Transgenic Learning for STEAM Subjects and Virtual Containers for OER

ERIC Educational Resources Information Center

Burgos, Daniel; Corbí, Alberto

2018-01-01

Transgenic learning is a disruptive approach in education. It encourages modification of moving parts of the educational chain. This article provides a view of transgenic learning focused on the delivery of enriched learning contents in STEAM areas. It discusses the mutagenic role that the virtual containers may play in current distance education.…

Harvesting Alternative Credit Transfer Students: Redefining Selectivity in Your Online Learning Program Enrollment Leads

ERIC Educational Resources Information Center

Corlett, Bradly

2014-01-01

Several recent issues and trends in online education have resulted in consolidation of efforts for Massive Open Online Courses (MOOCs), increased Open Educational Resources (OER) in the form of asynchronous course repositories, with noticeable increases in governance and policy amplification. These emerging enrollment trends in alternative online…

Open Educational Resources: American Ideals, Global Questions

ERIC Educational Resources Information Center

Weiland, Steven

2015-01-01

Educational relations between societies and cultures that begin with benevolent intentions can come to be seen as threats to national autonomy and local preferences. Indeed, side by side with the growth since the first years of this century of Open Educational Resources (OER) there has been worry about their impact on global educational…

Synthesis and characterization of different MnO2 morphologies for lithium-air batteries

NASA Astrophysics Data System (ADS)

Choi, Hyun-A.; Jang, Hyuk; Hwang, Hyein; Choi, Mincheol; Lim, Dongwook; Shim, Sang Eun; Baeck, Sung-Hyeon

2014-09-01

Manganese dioxide (MnO2) was synthesized in the forms of nanorods, nanoparticles, and mesoporous structures and the characteristics of these materials were investigated. Crystallinities were studied by x-ray diffraction and morphologies by scanning and transmission electron microscopy. Average pore sizes and specific surface areas were analyzed using the Barret-Joyner-Halenda and Brunauer-Emmett-Teller methods, respectively. Samples were also studied by cyclic voltammetry using 1M aqueous KOH solution saturated with either O2 or N2 as electrolytes to investigate their ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) activities. Of the samples produced, mesoporous MnO2 exhibited the highest ORR and OER catalytic activities. Mesoporous MnO2 supported on a gas diffusion layer was also used as a catalyst on the air electrode (cathode) of a lithium-air battery in organic electrolyte. The charge-discharge behavior of mesoporous MnO2 was investigated at a current density 0.2 mAcm-2 in a pure oxygen environment. Mesoporous MnO2 electrodes showed stable cycleability up to 65 cycles at a cell capacity of 700 mAhg-1.

Core–Shell Au@Metal-Oxide Nanoparticle Electrocatalysts for Enhanced Oxygen Evolution

DOE PAGES

Strickler, Alaina L.; Escudero-Escribano, Marı́a; Jaramillo, Thomas F.

2017-09-25

Enhanced catalysis for electrochemical oxygen evolution is essential for the efficacy of many renewable energy technologies, including water electrolyzers and metal–air batteries. Recently, Au supports have been shown to enhance the activity of many 3d transition metal-oxide thin films for the oxygen evolution reaction (OER) in alkaline media. In this paper, we translate the beneficial impact of Au supports to high surface area, device-ready core–shell nanoparticles consisting of a Au-core and a metal-oxide shell (Au@M xO y where M = Ni, Co, Fe, and CoFe). Through a systematic evaluation, we establish trends in performance and illustrate the universal activity enhancementmore » when employing the Au-core in the 3d transition metal-oxide nanoparticles. Finally, the highest activity particles, Au@CoFeO x, demonstrate an overpotential of 328 ± 3 mV over a 2 h stability test at 10 mA cm –2, illustrating that strategically coupling Au support and mixed metal-oxide effects in a core–shell nanoparticle morphology is a promising avenue to achieve device-ready, high-performance OER catalysts.« less

Core–Shell Au@Metal-Oxide Nanoparticle Electrocatalysts for Enhanced Oxygen Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strickler, Alaina L.; Escudero-Escribano, Marı́a; Jaramillo, Thomas F.

Enhanced catalysis for electrochemical oxygen evolution is essential for the efficacy of many renewable energy technologies, including water electrolyzers and metal–air batteries. Recently, Au supports have been shown to enhance the activity of many 3d transition metal-oxide thin films for the oxygen evolution reaction (OER) in alkaline media. In this paper, we translate the beneficial impact of Au supports to high surface area, device-ready core–shell nanoparticles consisting of a Au-core and a metal-oxide shell (Au@M xO y where M = Ni, Co, Fe, and CoFe). Through a systematic evaluation, we establish trends in performance and illustrate the universal activity enhancementmore » when employing the Au-core in the 3d transition metal-oxide nanoparticles. Finally, the highest activity particles, Au@CoFeO x, demonstrate an overpotential of 328 ± 3 mV over a 2 h stability test at 10 mA cm –2, illustrating that strategically coupling Au support and mixed metal-oxide effects in a core–shell nanoparticle morphology is a promising avenue to achieve device-ready, high-performance OER catalysts.« less

High-index faceted Ni3S2 nanosheet arrays as highly active and ultrastable electrocatalysts for water splitting.

PubMed

Feng, Liang-Liang; Yu, Guangtao; Wu, Yuanyuan; Li, Guo-Dong; Li, Hui; Sun, Yuanhui; Asefa, Tewodros; Chen, Wei; Zou, Xiaoxin

2015-11-11

Elaborate design of highly active and stable catalysts from Earth-abundant elements has great potential to produce materials that can replace the noble-metal-based catalysts commonly used in a range of useful (electro)chemical processes. Here we report, for the first time, a synthetic method that leads to in situ growth of {2̅10} high-index faceted Ni3S2 nanosheet arrays on nickel foam (NF). We show that the resulting material, denoted Ni3S2/NF, can serve as a highly active, binder-free, bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ni3S2/NF is found to give ∼100% Faradaic yield toward both HER and OER and to show remarkable catalytic stability (for >200 h). Experimental results and theoretical calculations indicate that Ni3S2/NF's excellent catalytic activity is mainly due to the synergistic catalytic effects produced in it by its nanosheet arrays and exposed {2̅10} high-index facets.

Engineering High-Energy Interfacial Structures for High-Performance Oxygen-Involving Electrocatalysis.

PubMed

Guo, Chunxian; Zheng, Yao; Ran, Jingrun; Xie, Fangxi; Jaroniec, Mietek; Qiao, Shi-Zhang

2017-07-10

Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn 3 O 4 nano-octahedrons (hi-Mn 3 O 4 ). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by Mn III -O present in hi-Mn 3 O 4 . The CoO/hi-Mn 3 O 4 demonstrates an excellent catalytic performance over the conventional metal oxide-based electrocatalysts, which is reflected by 1.2 times higher oxygen evolution reaction (OER) activity than that of Ru/C and a comparable oxygen reduction reaction (ORR) activity to that of Pt/C as well as a better stability than that of Ru/C (95 % vs. 81 % retained OER activity) and Pt/C (92 % vs. 78 % retained ORR activity after 10 h running) in alkaline electrolyte. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterogeneous Bimetallic Phosphide/Sulfide Nanocomposite for Efficient Solar-Energy-Driven Overall Water Splitting.

PubMed

Xin, Yanmei; Kan, Xiang; Gan, Li-Yong; Zhang, Zhonghai

2017-10-24

Solar-driven overall water splitting is highly desirable for hydrogen generation with sustainable energy sources, which need efficient, earth-abundant, robust, and bifunctional electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, we propose a heterogeneous bimetallic phosphide/sulfide nanocomposite electrocatalyst of NiFeSP on nickel foam (NiFeSP/NF), which shows superior electrocatalytic activity of low overpotentials of 91 mV at -10 mA cm -2 for HER and of 240 mV at 50 mA cm -2 for OER in 1 M KOH solution. In addition, the NiFeSP/NF presents excellent overall water splitting performance with a cell voltage as low as 1.58 V at a current density of 10 mA cm -2 . Combining with a photovoltaic device of a Si solar cell or integrating into photoelectrochemical (PEC) systems, the bifunctional NiFeSP/NF electrocatalyst implements unassisted solar-driven water splitting with a solar-to-hydrogen conversion efficiency of ∼9.2% and significantly enhanced PEC performance, respectively.

High-Efficiency Co/CoxSy@S,N-Codoped Porous Carbon Electrocatalysts Fabricated from Controllably Grown Sulfur- and Nitrogen-Including Cobalt-Based MOFs for Rechargeable Zinc-Air Batteries.

PubMed

Liu, Shengwen; Zhang, Xian; Wang, Guozhong; Zhang, Yunxia; Zhang, Haimin

2017-10-04

Developing bifunctional oxygen electrocatalysts with superior catalytic activities of oxygen reduction reaction (ORR) and oxygen revolution reaction (OER) is crucial to their practical energy storage and conversion applications. In this work, we report the fabrication of Co/Co x S y @S,N-codoped porous carbon structures with various morphologies, specific surface areas, and pore structures, derived from controllably grown Co-based metal-organic frameworks with S- and N-containing organic ligands (thiophene-2,5-dicarboxylate, Tdc; and 4,4'-bipyridine, bpy) utilizing solvent effect (e.g., water and methanol) under room temperature and hydrothermal conditions. The results demonstrate that Co/Co x S y @S,N-codoped carbon fibers fabricated at a pyrolytic temperature of 800 °C (Co/Co x S y @SNCF-800) from Co-MOFs fibers fabricated in methanol under hydrothermal conditions as electrocatalysts exhibit superior bifunctional ORR and OER activities in alkaline media, endowing them as air cathodic catalysts in rechargeable zinc-air batteries with high power density and good durability.

First report of vertically aligned (Sn,Ir)O2:F solid solution nanotubes: Highly efficient and robust oxygen evolution electrocatalysts for proton exchange membrane based water electrolysis

NASA Astrophysics Data System (ADS)

Ghadge, Shrinath Dattatray; Patel, Prasad P.; Datta, Moni K.; Velikokhatnyi, Oleg I.; Shanthi, Pavithra M.; Kumta, Prashant N.

2018-07-01

One dimensional (1D) vertically aligned nanotubes (VANTs) of (Sn0.8Ir0.2)O2:10F are synthesized for the first time by a sacrificial template assisted approach. The aim is to enhance the electrocatalytic activity of F doped (Sn,Ir)O2 solid solution electrocatalyst for oxygen evolution reaction (OER) in proton exchange membrane (PEM) based water electrolysis by generating (Sn0.8Ir0.2)O2:10F nanotubes (NTs). The 1D vertical channels and the high electrochemically active surface area (ECSA ∼38.46 m2g-1) provide for facile electron transport. This results in low surface charge transfer resistance (4.2 Ω cm2), low Tafel slope (58.8 mV dec-1) and excellent electrochemical OER performance with ∼2.3 and ∼2.6 fold higher electrocatalytic activity than 2D thin films of (Sn0.8Ir0.2)O2:10F and benchmark IrO2 electrocatalysts, respectively. Furthermore, (Sn0.8Ir0.2)O2:10F NTs exhibit excellent mass activity (21.67 A g-1), specific activity (0.0056 mAcm-2) and TOF (0.016 s-1), which is ∼2-2.6 fold higher than thin film electrocatalysts at an overpotential of 270 mV, with a total mass loading of 0.3 mg cm-2. In addition, (Sn0.8Ir0.2)O2:10F NTs demonstrate remarkable electrochemical durability - comparable to thin films of (Sn0.8Ir0.2)O2:10F and pure IrO2, operated under identical testing conditions in PEM water electrolysis. These results therefore indicate promise of (Sn0.8Ir0.2)O2:10F NTs as OER electrocatalysts for efficient and sustainable hydrogen production.

Porous LaCo1-xNixO3-δ Nanostructures as an Efficient Electrocatalyst for Water Oxidation and for a Zinc-Air Battery.

PubMed

Vignesh, Ahilan; Prabu, Moni; Shanmugam, Sangaraju

2016-03-09

Perovskites have emerged as promising earth-abundant alternatives to precious metals for catalyzing the oxygen evolution reaction (OER). Herein, we report the synthesis of a series of porous perovskite nanostructures, LaCo0.97O3-δ, with systematic Ni substitution in Co octahedral sites. Their electrocatalytic activity during the water oxidation reaction was studied in alkaline electrolytes. The electrocatalytic OER activity and stability of the perovskite nanostructure was evaluated using the rotating disk electrode technique. We show that the progressive replacement of Co by Ni in the LaCo0.97O3-δ perovskite structure greatly altered the electrocatalytic activity and that the La(Co0.71Ni0.25)0.96O3-δ composition exhibited the lowest OER overpotential of 324 and 265 mV at 10 mA cm(-2) in 0.1 M KOH and 1 M KOH, respectively. This value was much lower than that of the noble metal catalysts, IrO2, Ru/C, and Pt/C. Furthermore, the La(Co0.71Ni0.25)0.96O3-δ nanostructure showed outstanding electrode stability, with no observable decrease in performance up to 114th cycle in the auxiliary linear sweep voltammetry that lasted for 10 h in chronoamperometry studies. The excellent oxygen evolution activity of the La(Co0.71Ni0.25)0.96O3-δ perovskite nanostructure can be attributed to its intrinsic structure, interconnected particle arrangement, and unique redox characteristics. The enhanced intrinsic electrocatalytic activity of the La(Co0.71Ni0.25)0.96O3-δ catalyst was correlated with several parameters, such as the electrochemical surface area, the roughness factor, and the turnover frequency, with respect to variation in the transition metals of the perovskite structure. Subsequently, La(Co0.71Ni0.25)0.96O3-δ was utilized as the air cathode in a zinc-air battery application.

Solution Plasma-assisted Bimetallic Oxide Alloy Nanoparticles of Pt and Pd Embedded within Two-dimensional Ti3C2Tx Nanosheets as Highly Active Electrocatalysts for Overall Water-splitting.

PubMed

Cui, Bingbing; Hu, Bin; Liu, Jiameng; Wang, Minghua; Song, Yingpan; Tian, Kuan; Zhang, Zhihong; He, Linghao

2018-06-25

Exploiting high-efficiency and low-cost bifunctional electrocatalysts for hydrogen evolution (HER) and oxygen evolution reactions (OER) has been actively encouraged because of their potential applications in the field of clean energy. In this paper, we reported a novel electrocatalyst based on an exfoliated two-dimensional (2D) MXene (Ti3C2Tx) loaded with bimetallic oxide alloy nanoparticles (NPs) of Pt and Pd (represented by PtOaPdObNPs@Ti3C2Tx), which was synthesized via solution plasma (SP) modification. The prepared materials were then utilized as highly efficient bifunctional electrocatalysts toward HER and OER in alkaline solution. At a high plasma input power (200 W), bimetallic oxide alloy nanoparticles of Pt and Pd or nanoclusters with different metallic valence states deposited onto the Ti3C2Tx nanosheets. Due to the synergism of the noble metal NPs and the Ti3C2Tx nanosheets, the electrocatalytic results revealed that the as-prepared PtOaPdObNPs@Ti3C2Tx nanosheets under the plasma input power of 200 W for 3 min catalyst only required a low overpotential to attain 10 mA cm-2 for HER (57 mV) in 0.5 M H2SO4 solution and OER (1.63 V) in 0.1 M KOH sollution. Moreover, water electrolysis using this catalyst achieved a water splitting current density of 10 mA cm-2 at a low cell voltage of 1.53 V in 1.0 M KOH solution. These results suggested that the hybridization of the ultra-extremely low usage of PtOa/PdOb NPs (1.07 μg cm-2) and Ti3C2Tx nanosheets by SP will expand the applications of other clean energy reactions to achieve sustainable energy.

Open Educational Resources and College Textbook Choices: A Review of Research on Efficacy and Perceptions

ERIC Educational Resources Information Center

Hilton, John, III

2016-01-01

Textbooks are a vital component in many higher education contexts. Increasing textbook prices, coupled with general rising costs of higher education have led some instructors to experiment with substituting open educational resources (OER) for commercial textbooks as their primary class curriculum. This article synthesizes the results of 16…

Dimensions of Culturally Sensitive Factors in the Design and Development of Learning Objects

ERIC Educational Resources Information Center

Qi, Mei; Boyle, Tom

2010-01-01

Open educational resources (OERs) are designed to be globally reusable. Yet comparatively little attention has been given to the cultural issues. This paper addresses the issue of culturally sensitive factors that may influence the design of reusable learning objects. These influences are often subtle and hard to manage. The paper proposes a…

Faculty Perception of Openness and Attitude to Open Sharing at the Indian National Open University

ERIC Educational Resources Information Center

Panda, Santosh; Santosh, Sujata

2017-01-01

In the past decade, the educational scenario world over has significantly been impacted by open access and open education movements. The philosophy of openness and sharing forms the cornerstone of the open education movement. The distance education approaches, together with open educational resources (OER) and massive open online courses (MOOCs),…

Pragmatism vs. Idealism and the Identity Crisis of OER Advocacy

ERIC Educational Resources Information Center

Jhangiani, Rajiv Sunil

2017-01-01

The open education (OE) movement is in its adolescent years and experiencing an identity crisis as it is pulled towards both pragmatism (marked by an emphasis on cost savings, resources, and incremental change) and idealism (marked by an emphasis on permissions, practices, and radical change). In this article, I describe these tensions (free vs.…

Developing an Open Resource Bank for Interactive Teaching of STEM: Perspecives of School Teachers and Teacher Educators

ERIC Educational Resources Information Center

Hassler, Bjoern; Hennessy, Sara; Knight, Simon; Connolly, Teresa

2014-01-01

Much of the current literature related to Open Educational Resource (OER) development and practice concentrates on higher education, although a growing body of work is also emerging for the primary and secondary school sectors. This article examines the user perspectives of teachers and teacher educators, regarding: discovery of teaching…

Investigating the Effect of Users' Tagging Motivation on the Digital Educational Resources Metadata Descriptions

ERIC Educational Resources Information Center

Zervas, Panagiotis; Sampson, Demetrios G.; Aristeidou, Maria

2012-01-01

Over the past years, several Open Educational Resources (OERs) initiatives have been emerged worldwide aiming to create, share and reuse digital educational resources among educational communities. As a result, organizing, offering and accessing these resources over the web have been key issues for both the research and the educational community.…

"The Open Library at AU" (Athabasca University): Supporting Open Access and Open Educational Resources

ERIC Educational Resources Information Center

Elliott, Colin; Fabbro, Elaine

2015-01-01

To address challenges that learners, course creators, librarians and academics involved with OER and MOOCs are facing when looking for scholarly materials, Athabasca University Library has initiated the development of "the Open Library at AU." This open library is a full library website that provides easy access to open and free…