Enhancing Electrocatalytic NO Reduction to NH₃ by the CoS Nanosheet with Sulfur Vacancies

Electrochemical reduction of NO to NH₃ is of great significance for mitigating the accumulation of nitrogen oxides and producing valuable NH₃. Here, we demonstrate that the CoS nanosheet with sulfur vacancies (CoS_1-) behaves as an efficient catalyst toward electrochemical NO-to-NH₃ conversion. In 0.2 M Na₂SO₄ electrolyte, such CoS_1- displays a large NH₃ yield rate (44.67 μmol cm^-2 h^-1) and a high Faradaic efficiency (53.62%) at -0.4 V versus the reversible hydrogen electrode, outperforming the CoS counterpart (27.02 μmol cm^-2 h^-1; 36.68%). Moreover, the Zn-NO battery with CoS_1- shows excellent performance with a power density of 2.06 mW cm^-2 and a large NH₃ yield rate of 1492.41 μg h^-1 mg_cat.^-1. Density functional theory was performed to obtain mechanistic insights into the NO reduction over CoS_1-.