Molecular manganese catalyst anchored on Bi₂MoO₆ with enhanced photogenerated charges separation for efficient visible-light photoreduction of CO₂

Metal–organic hybrid composites are considered stable photocatalysts that exhibit effective CO₂ adsorption capability and high charge separation efficiency. Here, the reflux condensation method was used to synthesize organometallic complexes of 2,2-bipyridine-4,4-bisphosphonic acid tricarbonyl manganese bromide (MnP), which were then phosphate anchored onto Bi₂MoO₆ via a facile self-assembly method. The resulting Bi₂MoO₆/MnP (150:1) composites catalysts exhibited efficient photocatalytic reduction of CO₂ under visible light. The photocatalysts were systematically characterized via XRD, SEM, TEM, BET analysis, FTIR and UV–Vis. Visible light catalytic reduction products were detected qualitatively and quantitatively by ion chromatography and gas chromatography. The results demonstrate that loaded MnP reveal unique C=O, C–C characteristic peak and a peak fluorescence intensity that is less than 50% before loading. Furthermore, a remarkable CO production of turnover number TON_CO = 123 and methanol yield of 95 µmol g⁻¹ were obtained at a reaction time of 8 h under optimal conditions. The results due to the MnP in the composites not only enhanced charge carrier extraction but also improved photocatalytic reduction CO₂ performance. Overall, the Bi₂MoO₆/MnP composites exhibit good potential in the photocatalysts fields.