Influence of Aliovalent Substitutions on Oxygen Reduction on Tantalum Oxynitrides

Author(s)

Pasqualeti, Anielli M. ; Padgett, Elliot ; Kuo, Ding-Yuan ; Muller, David A. ; Lima, Fabio H. B. ; Suntivich, Jin

• Document type: Journal article
• Source: Journal of the Electrochemical Society; v. 164, n. 6, p. F645-F650, 2017.
• Web of Science Citations: 1

Abstract

The development of active and stable oxygen reduction reaction (ORR) electrocatalysts using low-cost, abundant elements is of critical importance to the widespread adoption of proton-exchanged membrane fuel cells (PEMFCs). Tantalum-containing compounds, such as tantalum oxynitrides, can catalyze ORR in acid, with the degree of oxidation proposed to play a central role in controlling the ORR activity. Herein, we report the incorporation of aliovalent ions in tantalum oxynitrides (Ta-ON) and their effect on the ORR activity in acid. We synthesize Ta-ON by utilizing urea as the nitrogen source and use aliovalent (Ti4+) and isovalent (Nb5+) substitutions to evaluate the influence of the aliovalent substitution on the ORR activity. We found that an aliovalent Ti4+ substitution increases the ORR activity by 3x, which we attribute to improved electrical conductivity and increased ORR active sites. In comparison, isovalent Nb5+ substitution or carbon inclusion as oxycarbonitride did not positively affect the ORR activity. Our finding points to the important role of defects and conductivity in the Ta-based ORR electrocatalysts. (C) The Author(s) 2017. Published by ECS. All rights reserved. (AU)

• FAPESP's process: 13/16930-7 - Electrocatalysis V: electrocatalytic processes of chemical and electrical energy interconversion
• Grantee: Edson Antonio Ticianelli
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/13323-0 - Carbon Dioxide and Water Electrochemistry: Application in Energy Conversion and Storage
• Grantee: Fabio Henrique Barros de Lima
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/03408-0 - Bifunctional Electrocatalysts for Reaction Involved in Regenerative Electrochemical Energy Conversion Devices that Operate with H2/O2.
• Grantee: Aniélli Martini Pasqualeti
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/11923-5 - Metal sulfide and oxide nanostructures as electrocatalysts for hydrogen and oxygen electrodes
• Grantee: Aniélli Martini Pasqualeti
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate