A Cu‐Cu<sub>2</sub>O/Ni<sub>2</sub>P Heterostructure for Efficient Tandem Catalysis of Electrosynthesis of Ammonia from Nitrate Reduction Reaction in Neutral Medium
Huilin Zhao, Pengfei Liu, Xuetao Cheng, Chao Fan, Jian Liu, Dongxiao Kan, Yanqin Wang
Abstract
Abstract Electrochemical nitrate reduction to ammonia (eNO 3 RR) in neutral conditions is an effective and sustainable method for ammonia production while treating nitrate pollution. Nevertheless, it still faces a great challenge due to the complicated multiple proton‐coupled‐electron process in eNO 3 RR. Herein, an efficient heterostructure electrocatalyst Cu‐Cu 2 O/Ni 2 P has been successfully fabricated for neutral ammonia electrosynthesis from nitrate reduction. Cu‐Cu 2 O/Ni 2 P exhibits outstanding eNO 3 RR performance with a Faradaic efficiency (FE) as high as 96.4% and ammonia yield rate of 14636 µg·h −1 ·cm −2 at −1.0 V (vs RHE) in 0.1 m PBS solution, which outperforms most of the reported eNO 3 RR electrocatalysts in neutral media. More importantly, the catalyst demonstrates an exceptional stability for 30 consecutive electrolysis cycles and outstanding durability even at large current density of 440 mA cm −2 in a flow cell. The tandem catalysis mechanism of NO 3 − → NO 2 − → NH 3 by the synergism of two components of Cu‐Cu 2 O and Ni 2 P in Cu‐Cu 2 O/Ni 2 P is verified by the experimental and theoretical calculations. Cu‐Cu 2 O has strong adsorption capacity for NO 3 − and which can be reduced into NO 2 − , while Ni 2 P can facilitate the water splitting, which promotes the abundant *H production, thus boosting the subsequent hydrogenation process during eNO 3 RR process whilst inhibiting the competitive hydrogen evolution reaction (HER).