Modulation of charge distribution enabling CuNi nano-alloys for efficient ammonia oxidation reaction to nitrite production

Electrochemical ammonia oxidation reaction (AOR) is a promising approach for ammonia conversion for its environmental benign and energy-saving features. Nitrite is an important member of the AOR pathway and plays a key role in many biological and industrial processes. To maximize the nitrite production efficiency, it is essential to design stable AOR electrocatalysts which can afford fast electron transfer and high partial current density. Herein, we present a CuNi nano-alloy by introducing Ni into the Cu lattice via a simple electrodeposition method. This CuNi nano-alloy strategy effectively modulates the charge distribution of Cu atoms and reduces the work function of the AOR electrocatalyst, resulting in enhanced electron transport properties as well as increased active sites. As a result, up to 95 % NH4+ conversion rate with a cumulative NO2− concentration of 3.3 g/L has been achieved on the Cu8Ni2 alloy catalysts at 1.6 V vs. RHE for 12 h. Significantly, the Cu8Ni2 alloy catalysts can perform stably for 50 h, demonstrating excellent durability for electrocatalytic AOR. Thus, this study provides an efficient, stable, and highly feasible Cu-Ni bimetallic catalyst for the selective and high-rate electrochemical AOR to produce nitrite.