Highly correlation of CO2 reduction selectivity and surface electron Accumulation: A case study of Au-MoS2 and Ag-MoS2 catalyst

Artificial photosynthesis from CO2 reduction to methane is severely hampered by the kinetically challenging eight-electron transfer process. Accumulated electrons has been demonstrated can decrease this kinetic barrier. However, charge accumulation were mainly reported in several homogenous systems because of its difficulties in heterogenous systems. Here we identify that highly accumulated electrons exist in Au loaded ultrathin MoS2 under light irradiation, resulting in a superior performance of CO2 reduction to methane. The selectivity for methane is up to 80 % with an average production rate of about 19.38 mu molg(-1) h(-1) in pure water. Further detailed studies reveal that plasmon-excited hot electrons transfer from Au to charged excitons in ultrathin MoS2 promotes electron accumulation and multi-electron CO2 reduction kinetics for methane generation. This is further supported by the CO2 reduction performance of Ag-MoS2. Along with the vanished accumulated electrons, CO is the main product with a selectivity of 98 %.