Steering the catalyst structure and intermediates adsorption configuration during pulsed nitrate electroreduction.

Abstract

The electroreduction of nitrate (NO₃^-) offers a promising pathway for carbon-free NH₃ production and nitrogen cycle management. Pulsed NO₃^- electroreduction has demonstrated to enable the improvement of catalytic performance, but the underlying mechanisms remain little understood. Herein, we tune the Cu catalyst structure and steer the key N-containing intermediate adsorption configuration during pulsed NO₃^- electroreduction. By applying different positive and negative potentials, in situ dynamic restructuring of the Cu catalyst and the regulation of local microenvironment have been revealed. According to detailed in situ characterizations and theoretical calculations, periodic Cu oxidation occurs within specific potential ranges from -0.2 V to 0.2 V vs. saturated Ag/AgCl, facilitating the transition of *NO adsorption configuration and thereby enhancing NH₃ formation. It can also increase NO₂^- coverage on Cu surface and inhibit side reactions. Conversely, the enhanced catalytic preformation in potential ranges from -1.2 V to -0.2 V was only attributed to the intrinsic characteristics of pulsed electrolysis. This study not only reveals the in-depth understanding of pulsed NO₃^- electrolysis, but also offers a general way of optimizing other electrocatalytic reactions.