Electron Redistribution of Copper/Ruthenium Catalysts for Efficient Synthesis of Ammonia via Accelerating the Hydrogenation of Intermediates

Abstract

The electrocatalytic nitrate reduction reaction (NO3RR) offers significant promise for environmental protection and the production of valuable ammonia (NH3). However, the complexity of the NO3RR process, involving various intermediates and active hydrogen species (Hads), poses challenges to enhancing the selectivity and yield of NH3. Herein, we present a highly active and selective CuRu alloy electrocatalyst (Cu50Ru50) that converts nitrate to ammonia with outstanding performance: a 97.2% Faradaic efficiency and a production rate of 41.3 mg h−1 cm−2 at −0.78 V vs RHE in 0.01 M nitrate. The catalyst shows excellent durability (>1000 h) and high efficiency in Zn-nitrate batteries, making it the benchmark electrocatalyst in this field. Ultraviolet photoelectron spectrometry results indicate the electron redistribution of Cu sites in Cu50Ru50, altering its electronic structure and optimizing its catalytic performance. Computational analysis and ultraviolet photoelectron spectrometry reveal that Cu atoms serve as active sites for NO3− adsorption, while Ru atoms enhance the dissociation of H2O, providing active Hads for the hydrogenation of intermediates, especially accelerating the rate-determining step of *NOH to form *NHOH.