Electrocatalytic Reduction of Low-Concentration Nitric Oxide into Ammonia over Ru Nanosheets

Electrocatalytic nitric oxide (NO) reduction represents a sustainable route from the point of view of environmental protection and ammonia generation. However, conversion from NO to ammonia under low NO concentrations is still a big challenge. Herein, Ru nanosheets with low coordination numbers (Ru-LCN) are prepared and exhibit high performance for electrocatalytic NO (1% v/v) reduction to ammonia under −0.2 V vs RHE (Faradaic efficiency, 65.96%; yield rate, 45.02 μmol·h–1·mgcat–1), obviously outperforming its counterpart of high coordination number Ru nanosheets (Faradaic efficiency, 37.25%; yield rate, 25.57 μmol·h–1·mg–1). Colorimetric methods and 1H nuclear magnetic resonance spectroscopy are performed to quantify ammonia. Through the combination of online differential electrochemical mass spectrometry (DEMS) and electrochemical in situ Fourier transform infrared (FTIR) spectroscopy with density functional theory calculations, the possible reaction pathway and enhanced mechanism are revealed. Constructing low coordination number Ru active sites is conducive to facilitating the adsorption of NO and reducing the reaction energy barrier of the potential-determining hydrogenation step.