Sulfur-regulated CoSe2 nanowires with high-charge active centers for electrochemical nitrate reduction to ammonium.

Abstract

Developing high-efficiency electrocatalysts for nitrate-to-ammonia transformation holds significant promise for the production of ammonia, a crucial component in agricultural fertilizers and as a carbon-free energy carrier. In this study, we propose a viable strategy involving sulfur doping to modulate both the microstructure and electronic properties of CoSe2 for nitrate reduction. This approach remarkably enhances the conversion of nitrate to ammonia by effectively regulating the adsorption capability of nitrogenous intermediates. Specifically, sulfur-doped CoSe2 nanowires (S-CoSe2 NWs) exhibit a peak faradaic efficiency of 93.1% at -0.6 V vs. RHE and achieve the highest NH3 yield rate of 11.6 mg h-1 cm-2. Mechanistic investigations reveal that sulfur doping facilitates the creation of highly charged active sites, which enhance the adsorption of nitrite and subsequent hydrogenation, leading to improved selectivity towards ammonia production.