Au-Added\nCuS Hollow Spheres to Regulate the Strength\nand Active Area of N<sub>2</sub> Adsorption Sites for Electrochemical\nNH<sub>3</sub> Production

Ammonia\nis a chemical compound in considerable global demand and\nplays a crucial role as an environmentally friendly energy carrier\nfor hydrogen energy storage. The electrochemical nitrogen reduction\nreaction (eNRR) using copper sulfide catalysts is being extensively\nstudied as an environmentally sustainable approach to the energy-intensive\nHaber–Bosch process for ammonia production. In this study,\nwe aimed to prepare CuS hollow spheres modified with Au nanoparticles\nusing an antisolvent crystallization-based method to be used as the\ncatalysts for eNRR. During the addition of Au to the CuS catalysts,\nthe nitrogen adsorption strength and surface area of the CuS catalysts\nare significantly regulated and expanded, leading to a noticeable\nenhancement in electrocatalytic performance for eNRR. Specifically,\nthe ammonia production rate of 2.4 μmol cm<sup>–2</sup> h or <i>j</i><sub>NH<sub>3</sub></sub> = 0.2 mA cm<sup>–2</sup> is achieved at a selectivity of 52% in neutral aqueous\nelectrolyte, which is more than a 2-fold increase compared to the\nunmodified CuS catalyst. The findings of this study can contribute\nto the development of sustainable and environmentally friendly ammonia\nproduction in the future.