In Situ Grown (Fe,Mn,Ga)3O4–x Spinel/(Mn,Fe)2O3–y Bixbyite Dual-Phase Electrocatalyst for Preeminent Nitrogen Reduction to Ammonia: A Step toward the NH3 Economy

• Published in: ACS applied energy materials 2023-08, Vol.6 (15), p.8063-8071
• Main Authors: Gemeda, Tadele Negash, Kuo, Dong-Hau, Sisay Wolde, Girma, Gultom, Noto Susanto
• Format: Article
• Language: English
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.3c01084

Employing a non-noble trimetal oxide system toward an electrochemical nitrogen reduction reaction (eNRR) instead of a century-long and CO2-emission Haber–Bosch process reveals a green path for NH3 production. In this work, the trimetal Fe–Mn–Ga oxide electrocatalyst was prepared with a facile one-pot hydrothermal method followed by annealing. Crystal structure, morphology, composition, and electrochemical properties were characterized. The flower-like (Fe,Mn,Ga)3O4–x spinel/tabular crystal-like (Mn,Fe)2O3–y bixbyite composite electrocatalyst was in situ formed with many active oxygen atoms on the oxygen vacancy sites and transition metals of Fe and Mn at multiple oxidation states. In a N2-saturated 0.1 M Na2SO4 solution, the NH3 yield rate at a potential of −0.6 V vs RHE is 814 μg h–1mgcat –1 (2036 μg h–1cm–2) with Faradaic efficiency (FE) of 5.77%, while the highest FE of 19.7% is achieved at −0.5 V with a yield rate of 599 μg h–1mgcat –1. The reaction mechanism for NH3 production is investigated and explained.