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 μmolg⁻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 %.