NiCoP ₄ O ₁₂ Nanosheets for Electroreduction of Nitrate to Ammonia

NiCoP 4 O 12 nanosheets on carbon cloth (NiCoP 4 O 12 /CC) are proposed to be a highly active electrocatalyst for ambient nitrate (NO 3 – ) reduction to ammonia (NH 3 ) compared to the NiCo-precursor nanowire array on CC (NiCo-pn/CC) and other control catalysts. In a 1 M electrolyte solution (NaOH + NaNO 3 ), NiCoP 4 O 12 achieves a high Faradaic efficiency of >90.0% in the cathodic potential region of −0.1 to −0.6 V and a large NH 3 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 NiCoP 4 O 12 refers to the faster hydrogenation of activated nitrate ions. A Zn-NO 3 – battery with a NiCoP 4 O 12 /CC cathode also shows record-high battery performance.