Work Function-Induced Electronic Modulation in NiCo Alloy for Electrochemical Nitrate Reduction

Abstract

The rational design of electrocatalysts is of great significance in the production of ammonia (NH₃) through a nitrate reduction reaction (NO₃^–RR). This article proposes a design approach to regulate electron redistribution and intermediate adsorption energy by adjusting the work function of alloy compounds. As an example, the NiCo alloy is successfully electrodeposited on carbon cloth (CC) using deep eutectic solvent (DES) as medium. The results show that the ammonia production rate of the NiCo alloy is as high as 1.55 mmol h^–1 cm^–2 at −0.38 V vs RHE, with the Faraday efficiency to be 84.94%, and the selectivity 94%. Experimental characterizations combined with density functional theory calculations confirm that alloying is beneficial for reducing the work function of Ni. This in turn adjusts the d-band center of the alloy to approach the Fermi level, changes the rate-determining step during the reduction reaction process, and consequently improves the performance. Eventually, an investigation is conducted on the Zn–NO₃^– battery fabricated with Ni₁Co₂/CC. This further exhibits the potential of Ni₁Co₂/CC within the energy conversion equipment. This study brings fresh design concepts and opportunities to the development of novel electrocatalysts for NO₃^–RR.