Crystallographic and Geometrical Dependence of Water Oxidation Activity in Co-Based Layered Hydroxides

• Autores: Sanchis-Gual, Roger; Hunt, Diego; Jaramillo, Camilo Juan; Seijas Da Silva, Alvaro; Mizrahi, Martin Daniel; Oestreicher, Víctor; Abellán, Gonzalo
• Año de publicación: 2023
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: CO-BASED ELECTROCATALYST; DFT CALCULATIONS; ELECTROCATALYSIS; LAYERED HYDROXIDES; LAYERED MATERIALS; OXYGEN EVOLUTION REACTION; WATER SPLITTING
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Cobalt-based layered hydroxides (LHs) stand out as one of the best families of electroactive materials for the alkaline oxygen evolution reaction (OER). However, fundamental aspects such as the influence of the crystalline structure and its connection with the geometry of the catalytic sites remain poorly understood. Thus, to address this topic, we have conducted a thorough experimental and in silico study on the most important divalent Co-based LHs (i.e., α-LH, β-LH, and LDH), which allows us to understand the role of the layered structure and coordination environment of divalent Co atoms on the OER performance. The α-LH, containing both octahedral and tetrahedral sites, behaves as the best OER catalyst in comparison to the other phases, pointing out the role of the chemical nature of the crystalline structure. Indeed, density functional theory (DFT) calculations confirm the experimental results, which can be explained in terms of the more favorable reconstruction into an active Co(III)-based oxyhydroxide-like phase (dehydrogenation process) as well as the significantly lower calculated overpotential across the OER mechanism for the α-LH structure (exhibiting lower Egap). Furthermore, ex situ X-ray diffraction and absorption spectroscopy reveal the permanent transformation of the α-LH phase into a highly reactive oxyhydroxide-like stable structure under ambient conditions. Hence, our findings highlight the key role of tetrahedral sites on the electronic properties of the LH structure as well as their inherent reactivity toward OER catalysis, paving the way for the rational design of more efficient and low-maintenance electrocatalysts.
Fil: Sanchis-Gual, Roger. Instituto de Ciencia Molecular(icmol); España
Fil: Hunt, Diego. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; Argentina
Fil: Jaramillo, Camilo Juan. No especifíca;
Fil: Seijas Da Silva, Alvaro. Universidad de Valencia; España
Fil: Mizrahi, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Fil: Oestreicher, Víctor. No especifíca;
Fil: Abellán, Gonzalo. Instituto de Ciencia Molecular(icmol); España. Instituto de Ciencia Molecular(icmol); España