Electron engineering of nickel phosphide for Niδ+ in electrochemical nitrate reduction to ammonia
Jie Hu, Hao Huang, Miao Yu, Shuang Wang, Jinping Li
Abstract
The electrochemical reduction of nitrate to ammonia (ENRA) provides an efficient approach to remove nitrate pollution and achieve ammonia production simultaneously. Herein, inspired by bio-enzyme in denitrifying bacteria, a carbon-coated nickel phosphide (NiPC) nanosheet derived from metal-organic frameworks (MOFs) is proposed as an efficient catalyst for ENRA. Through electron engineering, controllable Ni δ+ in nickel phosphide is achieved by regulating the degree of phosphating, which enhances its activity for the hydrogenation of nitrate. As the result, Ni δ+ becomes one of dominating factors determining the efficiency of the ENRA reaction in nickel phosphide. The optimal NiPC catalyst exhibits impressive property toward ENRA: NH 4 + Faraday efficiency of 96.68%, NH 4 + selectivity of 99.04%, and nitrate conversion rate of 90.43% under low nitrate concentration (200 mgL −1 ). This work opens a new avenue for the design of next-generation catalysts through electron engineering for ENRA.