Synthesis of Z-scheme alpha-Fe2O3/g-C3N4 composite with enhanced visible-light photocatalytic reduction of CO2 to CH3OH

摘要

In this study, a series of alpha-Fe2O3/g-C3N4(FCN) photocatalysts for CO2 reduction at 0.6 MPa to produce CH3OH is synthesized via hydrothermal method and the FCN hybrid shows greater absorption of visible light than pure g-C3N4 due to the introduction of alpha-Fe2O3 (narrow bandgap). The Z-scheme heterojunction promotes photogenerated electron and hole separation and suppresses the recombination of photoexcited electron-hole pairs. Benefiting from this unique structure, the optimized FCN(40:60) hybrid shows a CH3OH evolution rate of 5.63 mu mol g(-1) h(-1) without any sacrifice reagent and cocatalyst, which is 2.9 times higher than that of pure g-C3N4(1.94 mu mol g(-1) h(-1)). The excellent activity is ascribed to a Z-scheme transfer mechanism, which is proposed according to the band structure between g-C3N4 and alpha-Fe2O3. The results gained here may provide some illuminating insights for the design of new types of Z-scheme photocatalysts.