CuO/Bi₂CuO₄ Heterostructured Electrocatalyst for the Efficient Reduction of Nitrate to Ammonia

The electrochemical reduction of nitrate to ammonia (NH 3 ) not only provides an effective approach to balance the perturbed nitrogen cycle for addressing environmental issues but also provides a potential technology for green NH 3 synthesis. However, the process is limited by the produced intermediate-nitrite that tends to accumulate on cathode surfaces and multiple competing reactions. Herein, CuO/Bi 2 CuO 4 -450 heterostructures are reported as efficient electrocatalysts for the nitrate reduction reaction with extraordinary catalytic activities and selectivities for NH 3 production. The optimized catalyst achieves a remarkable Faradaic efficiency (96.49%) and exceptional NH 3 yield rate (9.17 mg h –1 mg cat. –1 ) at −0.5 V versus RHE, surpassing most of the reported Cu-based catalytic systems. The characterization results and theoretical evidence reveal that the interface effect originating from the strong interaction between Bi 2 CuO 4 and CuO tunes the electronic structures of the Cu and Bi active sites for optimized intermediate adsorption and lowers the rate-determining step reaction barriers, resulting in improved catalytic performance. This work offers a strategy to flexibly develop catalysts to promote electrocatalytic techniques for NH 3 production by electrochemical nitrate reduction.