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

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.