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.
Keywords: in situ Raman spectra; in situ reflection absorption imaging; intermediates; nitrate reduction reaction; selectivity.
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