Interfacial engineering of CoMoO4@MoS2/CoS2 heterostructure for enhancing electrochemical nitrate reduction to ammonia

Electrochemical nitrate reduction reaction (e-NO3RR) to ammonia not only can effectively remove nitrate pollutants but also is a green strategy for ammonia synthesis. However, the conversion from NO3− to NH3 involves some undesired by-products and severe competing hydrogen evolution reactions (HER), limiting its further development. Herein, the rodlike CoMoO4@MoS2/CoS2 heterostructure with rich interfaces is easily designed via hydrothermal followed by gas-phase sulfurization method for efficient electrochemical nitrate reduction to NH3. Benefiting from the interface effect, the optimal CoMoO4@MoS2/CoS2-5 exhibits an excellent e-NO3RR performance with a high NH3 Faradaic efficiency (FE) of 96.11% and an NH3 yield rate of 0.45 mmol h−1 mgcat−1 at −0.8 V (vs RHE), which is superior to that of CoMoO4 and MoS2/CoS2. The validation experiments suggest that the heterointerface can inhibit the generation of by-products and competing HER, and greatly facilitate the hydrogenation process.