CuOx/CoOx tandem catalyst for effectively reducing nitrate to ammonia

Abstract

Electrocatalytic nitrate reduction reaction (NO₃RR) offers a promising alternative to the Haber–Bosch process but requires efficient NH₄⁺ electrocatalysts with enhanced performance and selectivity. Although copper-based catalysts have been extensively researched and employed in electrocatalytic NO₃RR, the robust adsorption of intermediates and poor hydrolytic association activity of the catalysts result in reduced ammonia selectivity and interference of competing reactions. This study describes a nanoscale CuOx and CoOx coupling catalyst (CuOx/CoOx) with the most suitable ratio and tandem structure. Efficient and highly selective elimination of NO₃⁻ was accomplished through the tandem catalysis of two oxides. Efficient and notably selective elimination of NO₃⁻ was accomplished through the tandem catalysis of the two oxides. The CuOx/CoOx tandem catalyst achieved a NH₄⁺ selectivity of 90.1 %, NH₄⁺ Faraday efficiency of 95.3 % at a NO₃⁻ concentration of 400 mg/L with a cathodic potential of −0.58 V vs. RHE, and showed desirable stability, attributed to the twin lively website synergy and oxygen vacancy defects of the catalyst.