Copper oxide nanosheets for efficient electrochemical reduction of nitric oxide

The removal of nitric oxide (NO) is deemed essential due to its environmental detrimental effects, and electrocatalytic NO reduction reaction (NORR) for ammonia synthesis presents a sustainable approach. In this work, we synthesized copper oxide (CuO) nanosheet catalyst with a high specific surface area and abundant defects. This catalyst exhibited a remarkable 92.1% ammonia Faradaic efficiency (FE) in a flow cell, accompanied by a current density of 1.1 A cm⁻² and an ammonia production rate of 7356 µmol cm⁻² h⁻¹ at −0.26 V vs. reversible hydrogen electrode. The FE of ammonia remained above 80% during stability test for 50 h at a current density of more than 400 mA cm⁻². Quasi in situ X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy revealed that the CuO nanosheets were electrochemically reduced to monomeric copper during NORR. Compared with Cu nanoparticles, the CuO nanosheets showed a high electrochemical surface area and high intrinsic activity for NORR.