Reaction Mechanism for Oxygen Reduction on Platinum: Existence of a Fast Initial Chemical Step and a Soluble Species Different from H2O2

Autor(es)

Gomez-Marin, Ana ^{[1, 2]} ; Feliu, Juan ^[3] ; Edson, Ticianelli ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, Fis Quim, Caixa Postal 780, Av Trabalhador Sao Carlense, BR-13560970 Sao Carlos, SP - Brazil

^[2] Technol Inst Aeronaut ITA, Div Fundamental Sci IEF, Dept Chem, BR-12228900 Sao Paulo - Brazil

^[3] Univ Alicante, Inst Electroquim, Apt 99, E-03080 Alicante - Spain

• Tipo de documento: Artigo Científico
• Fonte: ACS CATALYSIS; v. 8, n. 9, p. 7931-7943, SEP 2018.
• Citações Web of Science: 6

Resumo

The oxygen reduction reaction (ORR) on platinum in perchloric acid is studied under transient conditions at stationary and nonstationary electrodes. Only under these conditions, the presence of a fast initial chemical step in the mechanism, giving rise to a soluble, short-lived intermediate proposed to be the HO2{*} radical, is revealed by comparing experimental and calculated curves by numerical simulations of simple reaction schemes. The formation of this species and the existence of a zero-current cycle involving it would be the main reasons for the lack of reduction currents at potentials higher than the ORB. reaction onset. Additionally, regardless of the exact subsequent steps after the initial chemical reaction, if HO2{*} is generated it would disproportionate to hydrogen peroxide, which implies that both species would be always produced during the ORR on Pt. The presence of HO2{*} and H2O2 would profoundly affect the durability of Pt-based catalysts and should be taken into account in the design of materials for fuel cell cathodes. (AU)

• Processo FAPESP: 14/23486-9 - Desenvolvimento de eletrocatalisadores nanoestruturados para a reação de eletro-redução de oxigênio: estudo da atividade e estabilidade
• Beneficiário: Ana Maria Gómez Marín
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/16930-7 - Eletrocatálise V: processos eletrocatalíticos de interconversão entre as energias química e elétrica
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático