Structure effects on electrocatalysts. Oxygen reduction on Te-modified Pt(111) surfaces: Site-blocking vs electronic effects

Autor(es)

Gomez-Marin, Ana Maria ^[1] ; Briega-Martos, Valentin ^[2] ; Feliu, Juan M. ^[2]

Afiliação do(s) autor(es)

^[1] Technol Inst Aeronaut ITA, Dept Chem, Div Fundamental Sci IEF, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Alicante, Inst Electroquim, Apt 99, E-03080 Alicante - Spain

• Tipo de documento: Artigo Científico
• Fonte: Journal of Chemical Physics; v. 152, n. 13 APR 7 2020.
• Citações Web of Science: 0

Resumo

In this work, the oxygen reduction reaction (ORR) on tellurium-modified Pt(111) surfaces has been studied. Adsorption of Te adatoms on Pt(111) progressively shifts toward less positive values of both the ORR reaction onset and the half-wave potential in 0.1M HClO4 for 0 < <theta>(Te) < 0.25. However, at <theta>(Te) > 0.25, the ORR activity increases relative to the one at theta (Te) < 0.25, but remains lower than that on clean Pt(111). Results were analyzed in light of simulations of kinetic currents as a function of <theta>(Te), calculated by employing a simple mean field model including both site blocking and electronic effects. Inside this framework, experimental data are best explained by considering that oxygenated Te species inhibit the ORR by either negatively modifying adsorption energies of reaction intermediates or combined site-blocking and electronic effects. A redox ORR catalysis due to redox properties of Te adatoms is discarded. Contrarily, in 0.05M H2SO4, a positive catalytic effect has been found, interpreted in terms of a competitive adsorption-desorption mechanism involving the replacement of adsorbed sulfate by Te adatoms. On the other hand, despite the strong site-blocking effect on H-ads and OHads adsorption by Te adatoms, it appears that the reduced Te-Pt(111) adlayer does not inhibit the reaction, suggesting different active sites for H-ads and OHads adsorption and for the rate-determining step of the ORR mechanism. (AU)

• Processo FAPESP: 19/04484-9 - Caracterização in situ da reação de redução de oxigênio sob materiais baseados no carbono por espectroscopia Raman amplificada por nano-partículas isoladas pela casca
• Beneficiário: Ana Maria Gómez Marín
• Modalidade de apoio: Bolsas no Exterior - Pesquisa