CoSe2 nanowire array enabled highly efficient electrocatalytic reduction of nitrate for ammonia synthesis

The electrocatalytic reduction of nitrate (NO₃^–) not only facilitates the environmentally sustainable production of ammonia (NH₃) but also purifies water by removing NO₃^–, thereby transforming waste into valuable resources. The process of converting NO₃^– to NH₃ is complex, involving eight electron transfers and multiple intermediates, making the choice of electrocatalyst critical. In this study, we report a cobalt selenide (CoSe₂) nanowire array on carbon cloth (CoSe₂/CC) as an effective electrocatalyst for the NO₃^– to NH₃ conversion. In an alkaline medium with 0.1 mol/L NO₃^–, CoSe₂/CC demonstrates exceptional NH₃ Faradaic efficiency of 97.6 % and a high NH₃ yield of 517.7 µmol h^–1 cm^–2 at –0.6 V versus the reversible hydrogen electrode. Furthermore, insights into the reaction mechanism of CoSe₂ in the electrocatalytic NO₃^– reduction are elucidated through density functional theory calculations.