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Steering the Selectivity of Electrochemical CO2 Reduction on the Cu Catalyst via the Interplay between the Electrode Morphology and Electrolyte Anion Identity

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Autor(es):
Obasanjo, Cornelius A. ; da Silva, Gelson T. S. T. ; Marin, Fatima Gonzalez ; Mascaro, Lucia H. ; Dinh, Cao-Thang
Número total de Autores: 5
Tipo de documento: Artigo Científico
Fonte: ACS CATALYSIS; v. 15, n. 7, p. 12-pg., 2025-03-24.
Resumo

Electrochemical carbon dioxide (CO2) reduction (ECR) holds promise as a viable pathway for the generation of fuels and chemicals. Several strategies have been explored to enhance the product selectivity of ECR on copper (Cu) catalysts. A systematic approach to optimize the local reaction microenvironment, however, remains elusive. Engineering the electrode structure and reaction microenvironment is a facile but effective strategy for steering the product selectivity of ECR reactions and can enable the rational design of highly selective Cu electrodes. Herein, we demonstrate that the synergy between an optimized Cu gas diffusion electrode (GDE) morphology and electrolyte anion identity can steer ECR product selectivity toward ethylene (C2+) or methane via the local CO2 availability, pH, and electrode morphology regulation. We show that using a relatively thin 100 nm Cu catalyst layer (CL) sputtered on an optimized macropore-sized hydrophobic poly(tetrafluoroethylene) substrate promotes methane selectivity at high reaction rates. We achieved a methane partial current density of 126 mA cm(-2) and a Faradaic efficiency (FE) of 42%. In contrast, a relatively thick 500 nm Cu CL favors ethylene production, reaching a high FE of 52% at 250 mA cm(-2) (with a total C2+ value of 77%) in a near-neutral KHCO3 electrolyte. Utilizing KI electrolyte significantly enhances methane selectivity, achieving ca. 56% at a partial current density of 168 mA cm(-2) while effectively suppressing the hydrogen evolution reaction (HER) on the thin CL. Furthermore, on the relatively thick CL, a higher C2+ FE of 84% was achieved at 250 mA cm(-2), demonstrating the impact of electrolyte anion identity and CL thickness on product selectivity in ECR. In addition, we find that a further increase in the Cu CL thickness does not result in a superior C2+ performance in KI compared to the KHCO3 electrolyte. Our result highlights the critical role of the interplay between Cu electrode morphology and the electrolyte anion identity, which can facilitate efficient CO2 mass transport, enable selective Cu sites, and tune local pH - thereby steering ECR product selectivity. (AU)

Processo FAPESP: 21/12394-0 - Métodos sintéticos sustentáveis empregando catálise, solventes verdes, reagentes seguros e materiais de partida renováveis
Beneficiário:Arlene Gonçalves Corrêa
Modalidade de apoio: Auxílio à Pesquisa - Temático
Processo FAPESP: 22/10255-5 - Arquiteturas baseadas em fosfetos e nitretos metálicos para conversão foto(eletro)química de CO2 em compostos C2+
Beneficiário:Gelson Tiago dos Santos Tavares da Silva
Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 23/10268-2 - Desenvolvimento de catalisadores a base de fosfetos metálico para eletroredução seletiva e eficiente de CO2
Beneficiário:Gelson Tiago dos Santos Tavares da Silva
Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
Processo FAPESP: 13/07296-2 - CDMF - Centro de Desenvolvimento de Materiais Funcionais
Beneficiário:Elson Longo da Silva
Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs