Synergistic effect of surface coated and bulk doped carbon on enhancing photocatalytic CO2 reduction for MgIn2S4 microflowers

Convert inert CO2 into chemical fuel via photocatalytic reduction is very intriguing. However, high charge recombination rate and inadequate CO2 absorption severely impede photocatalytic CO2 reduction activity. To address these drawbacks, we developed a strategy of MgIn2S4 modification by carbon. Two types of photocatalysts with carbon modifications, carbon-coated MgIn2S4 (MgIn2S4-SC); carbon coating and doping MgIn2S4 (MgIn2S4-Cx), were obtained and exhibited significantly enhanced catalytic activity. The CO evolution rate of MgIn2S4-C2 and MgIn2S4-SC reached 19.5 and 7.03 times higher than that of unmodified MgIn2S4, respectively. Our experimental and theoretical results disclosed that doped carbon for MgIn2S4 could prevent charge recombination in the bulk, facilitate CO2 adsorption, and decrease photocatalytic reaction energy barrier, while coated carbon could accelerate surface carrier migration, but had smaller and greater effect on fascinating CO2 adsorption and decreasing reaction energy barrier. The synergistic effect of surface coated and bulk doped carbon could maximize the photocatalysis efficiency.