Dual‐Site W‐O‐CoP Catalysts for Active and Selective Nitrate Conversion to Ammonia in a Broad Concentration Window

Abstract

Environmentally friendly electrochemical reduction of contaminated nitrate to ammonia (NO₃⁻RR) is a promising solution for large quantity ammonia (NH₃) production, which, however, is a complex multi‐reaction process involving coordination between different reaction intermediates of nitrate reduction and water decomposition‐provided active hydrogen (H_ads) species. Here, a dual‐site catalyst of [W‐O] group‐doped CoP nanosheets (0.6W‐O‐CoP@NF) has been designed to synergistically catalyze the NO₃⁻RR and water decomposition, especially the reactions between the intermediates of NO₃⁻RR and water decomposition‐provided H_adsspecies. This catalytic NO₃⁻RR exhibits an extremely high NH₃yield of 80.92 mg h⁻¹cm⁻²and a Faradaic efficiency (FE) of 95.2% in 1 

KOH containing 0.1 NO₃⁻. Significantly, 0.6W‐O‐CoP@NF presents greatly enhanced NH₃yield and FE in a wide NO₃⁻concentration ranges of 0.001–0.1 compared to the reported. The excellent NO₃⁻RR performance is attributed to a synergistic catalytic effect between [W‐O] and CoP active sites, in which the doped [W‐O] group promotes the water decomposition to supply abundant H_ads, and meanwhile modulates the electronic structure of Co for strengthened adsorption of H_adsand the hydrogen (H₂) release prevention, resultantly facilitating the NO₃⁻RR. Finally, a Zn‐NO₃⁻battery has been assembled to simultaneously achieve three functions: electricity output, ammonia production, and nitrate treatment in wastewater.