Core-Shell Engineering Boosted Active Hydrogen Generation in Cu_{2 - x} S/MoS ₂ Quantum Dots for Efficient Electrocatalytic Nitrate Reduction to Ammonia

The electrochemical nitrate reduction reaction (NO3RR) emerges as a promising method for ammonia (NH3) production, which faces the dilemma of inhibiting the hydrogen evolution reaction (HER) and promoting active hydrogen (H-ads) supply for hydrogenation of nitrogen intermediates. Here, a core-shell structure engineering strategy is developed for Cu2-xS/MoS2, where the strong H-ads adsorption and storage capacity can accelerate the hydrogenation of nitrogen intermediates. As a result, an eminent NH3 yield of 0.178 mmol h(-1) cm(-2) and a Faradaic efficiency of 84.5% were achieved. A series of electrochemical tests demonstrate that the tuning of the Cu2-xS/MoS2 interface can improve the electrochemical activity and the conversion of NO2-, while avoiding the strong HER that can effectively retain the H-ads. The density functional theory calculation further demonstrates that the Cu2-xS/MoS2 interface has a strong *H retention and adsorption ability to promote the NO3RR process. This work offers a novel perspective on the manipulation of H-ads generation for the NO3RR.