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Title: Role of Oxygen Vacancy Defects in the Electrocatalytic Activity of Substoichiometric Molybdenum Oxide

Abstract

Here, mesoporous α-MoO 3–x combined with poly(diallyldimethylammonium chloride)–functionalized reduced graphene oxide (PDDA–rGO) is introduced as an inexpensive and efficient oxygen reduction reaction (ORR) catalyst. The mesoporous catalysts are wrapped by conductive rGO sheets via an electrostatic interaction induced by a PDDA polyelectrolyte. The thermal interaction of PDDA with MoO 3 efficiently reduces the metal oxide to MoO 3–x at 400–600 °C, creating a surface oxygen vacancy. Through a combination of density functional theory and experiments, the role of the surface oxygen vacancy sites in the ORR activity of MoO 3–x is identified. For the first time, all the energy barriers against ORR are calculated at each step for MoO 3 with no oxygen vacancies and MoO 3–x with surface oxygen vacancies. It is shown that the presence of an Mo 4+-V$$..\atop{o}$$ oxygen vacancy site on the surface significantly reduces the energy barriers against ORR in the reaction pathways. An overpotential of 0.86 V (vs a reversible hydrogen electrode) with excellent electrochemical stability was obtained with the newly designed catalyst, with only a 9% decrease in the activity after ~17 h. These results offer a new paradigm in the defect engineering of metal oxides with a potential for the synthesis of stable and active noble metal-free ORR electrocatalysts.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [3];  [4]; ORCiD logo [5]
  1. Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science
  2. Univ. of Connecticut, Storrs, CT (United States). Dept. of Mechanical Engineering
  3. Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science; Ton Duc Thang Univ., Ho Chi Minh City (Vietnam). Advanced Functional Materials for Energy and Environmental Applications Research Group and Faculty of Applied Sciences
  4. Yale Univ., New Haven, CT (United States). Dept. of Chemistry
  5. Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science and Dept. of Mechanical Engineering; Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies (CINT)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); General Electric Co. (GE), Boston, MA (United States)
OSTI Identifier:
1466269
Alternate Identifier(s):
OSTI ID: 1485394
Report Number(s):
LA-UR-18-27143
Journal ID: ISSN 1932-7447; LA-UR-18-27143
Grant/Contract Number:  
AC52-06NA25396; CAREER-1553987; PD17-0137; TG-DMR170031
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 32; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Kashfi-Sadabad, Raana, Yazdani, Sajad, Huan, Tran Doan, Cai, Zhao, and Pettes, Michael Thompson. Role of Oxygen Vacancy Defects in the Electrocatalytic Activity of Substoichiometric Molybdenum Oxide. United States: N. p., 2018. Web. doi:10.1021/acs.jpcc.8b03536.
Kashfi-Sadabad, Raana, Yazdani, Sajad, Huan, Tran Doan, Cai, Zhao, & Pettes, Michael Thompson. Role of Oxygen Vacancy Defects in the Electrocatalytic Activity of Substoichiometric Molybdenum Oxide. United States. doi:10.1021/acs.jpcc.8b03536.
Kashfi-Sadabad, Raana, Yazdani, Sajad, Huan, Tran Doan, Cai, Zhao, and Pettes, Michael Thompson. Mon . "Role of Oxygen Vacancy Defects in the Electrocatalytic Activity of Substoichiometric Molybdenum Oxide". United States. doi:10.1021/acs.jpcc.8b03536. https://www.osti.gov/servlets/purl/1466269.
@article{osti_1466269,
title = {Role of Oxygen Vacancy Defects in the Electrocatalytic Activity of Substoichiometric Molybdenum Oxide},
author = {Kashfi-Sadabad, Raana and Yazdani, Sajad and Huan, Tran Doan and Cai, Zhao and Pettes, Michael Thompson},
abstractNote = {Here, mesoporous α-MoO3–x combined with poly(diallyldimethylammonium chloride)–functionalized reduced graphene oxide (PDDA–rGO) is introduced as an inexpensive and efficient oxygen reduction reaction (ORR) catalyst. The mesoporous catalysts are wrapped by conductive rGO sheets via an electrostatic interaction induced by a PDDA polyelectrolyte. The thermal interaction of PDDA with MoO3 efficiently reduces the metal oxide to MoO3–x at 400–600 °C, creating a surface oxygen vacancy. Through a combination of density functional theory and experiments, the role of the surface oxygen vacancy sites in the ORR activity of MoO3–x is identified. For the first time, all the energy barriers against ORR are calculated at each step for MoO3 with no oxygen vacancies and MoO3–x with surface oxygen vacancies. It is shown that the presence of an Mo4+-V$..\atop{o}$ oxygen vacancy site on the surface significantly reduces the energy barriers against ORR in the reaction pathways. An overpotential of 0.86 V (vs a reversible hydrogen electrode) with excellent electrochemical stability was obtained with the newly designed catalyst, with only a 9% decrease in the activity after ~17 h. These results offer a new paradigm in the defect engineering of metal oxides with a potential for the synthesis of stable and active noble metal-free ORR electrocatalysts.},
doi = {10.1021/acs.jpcc.8b03536},
journal = {Journal of Physical Chemistry. C},
number = 32,
volume = 122,
place = {United States},
year = {2018},
month = {7}
}

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