Cu/2D-CuO_x Nanocomposites with Abundant Oxygen Vacancy Defects for Enhancing Ammonia Selectivity of Electrocatalytic Nitrate Reduction

At present, a variety of catalysts have been studied and used for the electrocatalytic reduction of nitrate. However, it is still a great challenge to improve the selectivity of the electrocatalytic nitrate reduction reaction (NO₃^–RR) catalyst for ammonia and reduce the activity of the competitive reaction. Herein, two-dimensional CuO_x nanosheets with abundant oxygen vacancy defects were in situ grown on Cu nanoparticles to construct Cu/2D-CuO_x composite nanomaterials as nitrate reduction electrocatalysts. The two-dimensional (2D) nanosheet morphology facilitated the exposure of active sites and promoted the mass/charge transfer process during electrocatalysis. As a result, the synergistic effect of abundant oxygen vacancy defects and the 2D nanosheet-like structure on the surface of the catalyst endows the Cu/2D-CuO_x with superior performance for the nitrate reduction reaction, achieving high ammonia selectivity (97.56%) and NH₄⁺ yield (1476 μg h^–1 mg^–1).