Hybrid photocatalytic systems comprising a manganese complex anchored on g-C3N4 for efficient visible -light photoreduction of CO2

Inorganic organic composites are triggering an increasing interest in the photocatalytic reduction of CO2 due to its stability and high efficiency. In this study, the reflux condensation method was used to synthesize 2,2-bipyridine-4,4-bisphosphonic acid tricarbonyl manganese bromide complex (MnP), which was then anchored onto g-C3N4 via a facile self-assembly method. The resulting g-C3N4/MnP composites catalysts exhibited efficient photocatalytic reduction of CO2 under visible light irradiation. Moreover, the yield of CO of g-C3N4/MnP catalyst was 5 times more compared with pure g-C3N4 catalyst. Additionally, the only product of catalytic reduction of CO2 was CO. These results were attributed to that the Mn complex played important role in the photocatalytic reduction of CO2 to CO by the composite catalyst. An integrated "Z-scheme" mechanism was proposed for CO2 reduction using the g-C3N4/MnP system. This hybrid photocatalyst system has good application prospects in the field of photocatalysis owing to its environmental friendliness and strong visible- light absorption.