Cobalt phosphide nanorings towards efficient electrocatalytic nitrate reduction to ammonia

High-quality CoP nanorings (CoP NRs) are easily achieved using a phosphorating treatment of CoOOH nanorings, and reveal high activity towards the hydrogen evolution reaction and the nitrate electrocatalytic reduction reaction due to substantial coordinately unsaturated active sites, a high surface area, and available mass transfer pathways. Consequently, the CoP NRs can achieve a faradaic efficiency of 97.1% towards NO3−-to-NH3 conversion and provide an NH3 yield of 30.1 mg h−1 mg−1cat at a −0.5 V potential.