Promoting nitric oxide electroreduction to ammonia over electron-rich Cu modulated by Ru doping

Electrocatalytic nitric oxide (NO) reduction is a promising strategy to produce ammonia. Developing a facile approach to synthesize efficient catalysts with enhanced NO electroreduction performance is highly desirable. Here, a series of Ru-doped Cu materials are constructed through in situ electroreduction of corresponding metal hydroxides. The optimized Ru0.05Cu0.95 exhibits superior electrocatalytic performance for ammonia synthesis by using NO/Ar (1/4, n/n) as the feedstocks (Faradaic efficiency: 64.9%, yield rate: 17.68 μmol cm−2 h−1), obviously outperforming Cu counterpart (Faradaic efficiency: 33.0%, yield rate: 5.73 μmol cm−2 h−1). Electrochemical in situ Fourier transform infrared (FTIR) spectroscopy and online differential electrochemical mass spectrometry (DEMS) are adopted to detect intermediates and unveil the possible reaction pathway. The downshift of the Cu d-band center induced by Ru doping facilitates the rate-limiting hydrogenation step and decreases the desorption energy of NH3, leading to high Faradaic efficiency and yield of ammonia.