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

Abstract

AbstractEnvironmentally 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 (Hads) 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 Hadsspecies. 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 mKOH containing 0.1 mNO3−. Significantly, 0.6W‐O‐CoP@NF presents greatly enhanced NH3yield and FE in a wide NO3−concentration ranges of 0.001–0.1 mcompared 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 Hads, and meanwhile modulates the electronic structure of Co for strengthened adsorption of Hadsand 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.