Efficient Ammonia Electrosynthesis and Energy Conversion through a Zn‐Nitrate Battery by Iron Doping Engineered Nickel Phosphide Catalyst
Rong Zhang, Ying Guo, Shaoce Zhang, Dong Chen, Yuwei Zhao, Zhaodong Huang, Longtao Ma, Pei Li, Qi Yang, Guojin Liang, Chunyi Zhi
Abstract
Abstract The electrocatalytic nitrate reduction reaction (NO 3 ‐RR) to ammonia (NH 3 ) offers a promising alternative approach for NH 3 production and nitrate‐based voltaic cells which can deliver both electricity and NH 3 as products, are also highly attractive. However, nitrate‐to‐NH 3 conversion involves a proton‐assisted multiple‐electron transfer process with considerable kinetic barrier, underlying the need for efficient catalysts for the NO 3 – RR. A Zn‐nitrate battery is reported to enable a “killing three birds with one stone” strategy for energy supply, ammonia production and removal of pollutants with the iron doped nickel phosphide (Fe/Ni 2 P) as a NO 3 – RR catalyst electrode. Iron doping induces a downshift of the d‐band center of Ni atoms to the Fermi level, allowing the optimization of Gibbs free energies for reaction intermediates. The Fe/Ni 2 P catalyst exhibits 94.3% NH 3 Faradaic efficiency (FE) and nearly 100% nitrate conversion efficiency at –0.4 V vs. reversible hydrogen electrode (RHE). Further applying this highly efficient NO 3 – RR electrocatalyst as the cathode material, a novel Zn‐nitrate battery exhibits a power density of 3.25 mW cm –2 and a FE of 85.0% for NH 3 production. This work enriches the application of Zn‐based batteries in the field of electrocatalysis and highlights the promise of bimetal phosphide for the NO 3 – RR.