Nitrogen doped MoS2 and nitrogen doped carbon dots composite catalyst for electroreduction CO2 to CO with high Faradaic efficiency

CO2 utilization by direct electroreduction offers an attractive route for preparing valuable chemicals or alternative liquid fuels, and mitigating the hazardous effects of global warming. Unfortunately, the electroreduction CO2 currently suffers from poor efficiency, low produce selectivity, and large overpotential is required to initiate CO2 reduction due to the thermodynamic stability of CO2. Therefore, the development of low-cost transition-metal chalcogenides electrocatalysts for high selectivity electroreduction CO2 under considerably low overpotentials are still challenge, due to its high catalytic activity of hydrogen evolution reaction and poor electronic conductivity. Herein, for the first time, N-doped MoS2 nanosheets and N-doped carbon nanodots (N-MoS2@NCDs) composite was successfully prepared by solvothermal method in the presence of E-MoS2 and DMF solvent. During solvothermal process, N atoms were introduced into MoS2 framework and N-doped CDs were formed on the surface of MoS2 nanosheets at the same time. The optimized N-MoS2@NCDs-180 for electroreduction CO2 displayed a high CO Faradaic efficiency up to 90.2% and a low onset overpotential requirement of 130 mV for CO formation, which were significantly superior to those of the E-MoS2 and other previously reported transition-metal sulfides electrocatalysts. The experiment verified that the N-doped CDs on the surface MoS2 provided a good electrical conductivity, which accelerated electron transport. Moreover, DFT theoretical calculation demonstrated that the N doping into MoS2 could decrease the energy barrier of the COOH* intermediate formation and create more electrons on the edge Mo of N-MoS2, thereby enhancing catalytic activity of CO2 electroreduction to CO.