In Situ Structural Evolution and Activity Descriptor of Atomically Dispersed Catalysts During Nitrate Electroreduction

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Braga, Daniel S. ; Pedersen, Angus ; Riyaz, Mohd ; Barrio, Jesus ; Bagger, Alexander ; Neckel, Itamar T. ; Mariano, Thiago M. ; Winkler, Manuel E. G. ; Stephens, Ifan E. L. ; Titirici, Maria-Magdalena ; Nagao, Raphael

• Tipo de documento: Artigo Científico
• Fonte: ADVANCED SCIENCE; v. 12, n. 39, p. 14-pg., 2025-08-22.

Resumo

Single-Atom Catalysts (SAC) have emerged as a promising class of materials for various catalytic applications, including the electrochemical nitrate reduction reaction (eNO(3)RR) and consequently ammonia production. While the efficiency and selectivity of these materials have been extensively highlighted for the eNO(3)RR, the in situ evolution to their structure and composition during electrocatalysis is largely unexplored and lacks catalyst design principles. To solve this, we investigated a series of high utilization metal-nitrogen-carbon (MNC) SACs (M = Cr, Fe, Co, Ni, and Cu) for eNO(3)RR. Except for CuNC, which selectively produced nitrite, all catalysts exhibited Faradaic efficiencies (FE) for ammonia exceeding 50%. NiNC demonstrated the highest performance (FE of 78.0 +/- 2.9% at -0.4 V versus reversible hydrogen electrode (RHE) at pH 13 and maximum ammonia production rate of 615.7 +/- 176.5 mu mol.h(-1).cm(geo)(-2) , corresponding to an energy efficiency of 15.1 +/- 1.4% at -0.6 V-RHE), followed by CoNC. In situ Synchrotron X-ray fluorescence (SXRF) mapping at various cathodic potentials (from open circuit potential to 0.0 V-RHE and then -0.6 V-RHE at 100 mV steps) revealed significant mobility of Ni within the carbon matrix, leading to the formation of metallic clusters from 0.0 V-RHE. Similar in situ metal clustering is observed for CoNC. Structure-activity plots are generated from both MNC literature and results obtained here, finding a clear trend between OH binding energy and turnover frequency, with the high activity of NiNC and CoNC in this work explained by their stronger OH binding in the metallic structure compared to their SAC coordination. This work therefore, reveals the structure-activity-stability of MNCs for eNO(3)RR and provides a simple descriptor for identifying highly active eNO(3)RR catalysts and their in situ structural evolution. (AU)

• Processo FAPESP: 24/03807-7 - Redução Eletroquímica de Nitrato à Amônia Catalisada por Átomos Isolados e Óxidos Metálicos
• Beneficiário: Raphael Nagao de Sousa
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 23/02841-4 - Eletrodos de Co3O4/CuO/Cu para redução eletroquímica de nitrato
• Beneficiário: Raphael Nagao de Sousa
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/11986-5 - Geração e Armazenamento de Novas Energias: trazendo desenvolvimento tecnológico para o país
• Beneficiário: Ana Flávia Nogueira
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa Aplicada
• Processo FAPESP: 23/10045-3 - Eletrodos de Co3O4/CuO/Cu para redução eletroquímica de nitrato
• Beneficiário: Manuel Edgardo Gomez Winkler
• Modalidade de apoio: Bolsas no Brasil - Programa Fixação de Jovens Doutores