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

The electrochemical reduction of nitrate to ammonia (NH3) not only provides an effective approach to balance the perturbed nitrogen cycle for addressing environmental issues but also provides a potential technology for green NH3 synthesis. However, the process is limited by the produced intermediate-nitrite that tends to accumulate on cathode surfaces and multiple competing reactions. Herein, CuO/Bi2CuO4-450 heterostructures are reported as efficient electrocatalysts for the nitrate reduction reaction with extraordinary catalytic activities and selectivities for NH3 production. The optimized catalyst achieves a remarkable Faradaic efficiency (96.49%) and exceptional NH3 yield rate (9.17 mg h-1 mgcat.-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 Bi2CuO4 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 NH3 production by electrochemical nitrate reduction.