Enhanced electrocatalytic nitrate reduction and energy conversion through Zn-Nitrate battery by Cu3P@Co(OH)2/CF heterostructure catalyst

Electrocatalytic nitrate reduction reaction (NO3RR) provides a promising method for ammonia (NH3) producing. It is urgent to develop efficient catalysts with improved NO3RR performance. In this paper, Cu3P@Co(OH)2/CF heterostructure catalyst is constructed by electrodeposition of cobalt hydroxide (Co(OH)2) nanosheet on the surface of copper phosphide (Cu3P) nanorod, and used as a self-supporting cathode for electrocatalytic reduction of nitrate to ammonia. The NH3 yield reaches 0.19 mmol h−1 cm−2 at a potential of −0.17 V vs. RHE, and the faraday efficiency (FE) is 86.7 %. The study manifests that the built-in electric field generated at the p-n heterojunction interface optimizes the electron migration kinetics, and promotes the adsorption of nitrate and the convention of intermediate product NO2− into ammonia. As a consequence, the selectivity of NH3 is improved. The Zn-nitrate battery is assembled with the designed catalyst as the cathode, to reach a peak power density of 5.16 mW cm−2. The prepared catalyst realizes three effective functions: power output, ammonia synthesis, and nitrate pollutants treatment.