All-electrochemically synthesized tin and nickel oxide-modified hematite as photo-electrocatalyst anodes for solar-driven water splitting

Autor(es)

Silva, Anelisse B. ^[1] ; da Silva, Camila D. F. ^[1] ; Souza, Flavio L. ^{[2, 3]} ; Lucas, Francisco W. S. ^[1] ; Lima, Fabio H. B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem Sao Carlos, Trabalhador Sao Carlense Av 400, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210170 Santo Andre, SP - Brazil

^[3] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Nanotechnol Natl Lab LNNano, BR-13083970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF CATALYSIS; v. 391, p. 273-281, NOV 2020.
• Citações Web of Science: 2

Resumo

Sn- and NiOx-modified Fe2O3 (hematite) films were entirely synthesized via electrodeposition procedure, followed by thermal treatment, and tested as photo-electrocatalyst for water splitting, in alkaline electrolyte. The optimization of the Sn and NiOx electrodeposition loadings on Fe2O3 produced a maximum photocurrent density of 1.35 mA cm(-2) at 1.23 V (vs. RHE), with the highest shift on the reaction onset potential, representing a large improvement in relation to bare hematite. Long-term photoelectrolysis studies of the Fe2O3/Sn-10/NiOx at 1.23 V showed that the photocurrent density remained stable for at least 24 h. The assessment of the results from the calculations of charge separation (eta(sep)) and charge injection (eta(cat)) efficiencies revealed an improvement in both parameters, with the addition of tin into hematite. This was ascribed to its beneficial effect on lowering the charge recombination of the photogenerated charge carriers on grain-boundaries and on the hematite/electrolyte interface. Additionally, it was evidenced that NiOx was more important on the increase in the charge injection, since it is a hole collector, acting as co-catalyst, which improves charge transfer rate at the interface with the electrolyte. The outcome of the Mott-Schottky analysis displayed a negative shift of the flat band potentials (E-fb) for both, Sn- and NiOx-modified photo-electrocatalysts, due to the passivation of the surface states, and this was in agreement with the mathematical fitting of the curves obtained via photoelectrochemical impedance spectroscopy (PEIS) measurements. The present findings clearly showed that, by allowing a fine-tuning of the amount of the metal modifiers and with an efficient deposition at functional sites of the hematite, this electrodeposition method is a promising strategy to boost hematite performance as photo-electrocatalyst. (C) 2020 Elsevier Inc. All rights reserved. (AU)

• 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
• Processo FAPESP: 19/22183-6 - Electrocatálise VI: aspectos fundamentais e aplicados em problemas emergentes e clássicos em conversão eletroquímica de energia
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 16/13323-0 - Eletroquímica do Dióxido de Carbono e da Água: Aplicação em Estocagem e Aproveitamento de Energia
• Beneficiário: Fabio Henrique Barros de Lima
• Modalidade de apoio: Auxílio à Pesquisa - Regular