Investigating the role of oxygen vacancies in metal oxide for enhanced electrochemical reduction of NO₃⁻ to NH₃: mechanistic insights

Abstract

Ammonia (NH3) is a crucial chemical commodity used extensively in fertilizer production and as a renewable potential energy carrier.

Recent Progress and Perspectives on Transition Metal-Based Electrocatalysts for Efficient Nitrate Reduction

“…Therefore, the study of bimetallic oxides is the focus of the current research on metal oxides, such as Cu-Co oxides, 78,113,114,119,123 Cu-Ni oxides, 124 Fe-Ni oxides, 42,125 and Co-Mn oxides, 126 whose excellent catalytic performance in electrochemical nitrate reduction is not only due to the excellent catalytic performance of the transition metals themselves but also because of the role of the heterojunction. The Ni 0.8 Cu 0.2 O@CuO@NF composites prepared by Hu et al 124 In addition, the oxygen vacancies (O v s) in metal oxides can achieve faster electron transfer 127 and stronger adsorption of oxygen atoms in nitrate, whereas O v s provide electrons for nitrogen in nitrate to promote adsorption and activation, thereby enhancing the catalytic performance. Tang et al 51 prepared sea urchin-like titanium dioxide particles (U-TiO 2 ) with surfaces enriched with O v s. Their NH 3 selectivity at −0.60 V was as high as 98.1%, which is higher than the selectivities of most previously reported catalysts, demonstrating that O v s are the true reaction sites for catalytic reactions, and they also facilitate the mass transfer process and electron transfer.…”

“…In addition, the oxygen vacancies (O v s) in metal oxides can achieve faster electron transfer and stronger adsorption of oxygen atoms in nitrate, whereas O v s provide electrons for nitrogen in nitrate to promote adsorption and activation, thereby enhancing the catalytic performance. Tang et al prepared sea urchin-like titanium dioxide particles (U-TiO 2 ) with surfaces enriched with O v s. Their NH 3 selectivity at −0.60 V was as high as 98.1%, which is higher than the selectivities of most previously reported catalysts, demonstrating that O v s are the true reaction sites for catalytic reactions, and they also facilitate the mass transfer process and electron transfer.…”