Visible Light-Driven CO 2 Photocatalytic Reduction by Co-porphyrin-Coupled MgAl Layered Double-Hydroxide Composite

CO₂ photocatalytic reduction into fuels has provided a sustainable strategy for the mitigation of energy crisis and environmental problems. MgAl layered double hydroxide (LDH), with the advantages of low cost and wide employment in commercial applications, has been regarded as a promising catalyst for CO₂ photocatalytic conversion. In order to improve the visible light absorption and charge separation efficiency of MgAl LDH, metalloporphyrin (Co-TCPP) was used for the surface modification of MgAl LDH to prepare the noble metal-free nanocomposite ([email protected]). The synthesized catalyst exhibits increased photocatalytic activity under visible light irradiation compared with pure MgAl LDH. Experimental results show that 20% [email protected] exhibits the highest photocatalytic activity with the CO evolution rate of 0.40 μmol g_cat^–1, which is about 4.1 times and 3.3 times higher than those of MgAl LDH and Co-TCPP. The excellent visible light absorption of porphyrin molecules can effectively widen the light absorption edge of the heterogeneous photocatalyst to the low energy region (600–800 nm). The intramolecular heterogeneous interface and the highly dispersed cobalt metal sites can facilitate charge transport and separation.