NiCoP ₄ O ₁₂ Nanosheets for Electroreduction of Nitrate to Ammonia

NiCoP4O12 nanosheets on carbon cloth (NiCoP4O12/CC) are proposed to be a highly active electrocatalyst for ambient nitrate (NO3–) reduction to ammonia (NH3) compared to the NiCo-precursor nanowire array on CC (NiCo-pn/CC) and other control catalysts. In a 1 M electrolyte solution (NaOH + NaNO3), NiCoP4O12 achieves a high Faradaic efficiency of >90.0% in the cathodic potential region of −0.1 to −0.6 V and a large NH3 yield of up to 1.1 mmol h–1 cm–2. The phosphorylation of the NiCo-pn/CC nanowire array results in the replacement of the hydroxide environment by the metaphosphate unit, which is responsible for the modulation of the surface morphology and electronic structure. The superior catalytic activity of NiCoP4O12 refers to the faster hydrogenation of activated nitrate ions. A Zn-NO3– battery with a NiCoP4O12/CC cathode also shows record-high battery performance.