A Bi-Co Corridor Construction Effectively Improving the Selectivity of Electrocatalytic Nitrate Reduction toward Ammonia by Nearly 100.

Abstract

Improving the selective ammonia production capacity of electrocatalytic nitrate reduction reaction (NO₃ RR) at ambient conditions is critical to the future development and industrial application of electrosynthesis of ammonia. However, the reaction involves multi-proton and electron transfer as well as the desorption and underutilization of intermediates, posing a challenge to the selectivity of NO₃ RR. Here the electrodeposition site of Co is modulated by depositing Bi at the bottom of the catalyst, thus obtaining the Co+Bi@Cu NW catalyst with a Bi-Co corridor structure. In 50 mm NO₃ ^- , Co+Bi@Cu NW exhibits a highest Faraday efficiency of ≈100% (99.51%), an ammonia yield rate of 1858.2 µg h^-1  cm^-2 and high repeatability at -0.6 V versus the reversible hydrogen electrode. Moreover, the change of NO₂ ^- concentration on the catalyst surface observed by in situ reflection absorption imaging and the intermediates of the NO₃ RR process detected by electrochemical in situ Raman spectroscopy together verify the NO₂ ^- trapping effect of the Bi-Co corridor structure. It is believed that the measure of modulating the deposition site of Co by loading Bi element is an easy-to-implement general method for improving the selectivity of NH₃ production as well as the corresponding scientific research and applications.