Metal–organic framework (MOF) composite materials for photocatalytic CO2 reduction under visible light

Abstract

The tridentate ligand 2,4,6-tris(2-(pyridin-4-yl)vinyl)-1,3,5-triazine (TPVT) was designed and synthesized. We prepared metal–organic framework (TPVT-MOFs) crystals containing TPVT, 1,3,5-benzenetricarboxylic acid and cobalt by solvothermal reaction. Then, a series of composite materials with different contents of TPVT-MOFs were obtained by combining TPVT-MOFs with g-C₃N₄. Due to the interaction between TPVT-MOFs and g-C₃N₄, the composite materials have a more favorable valence band (VB) and conduction band (CB) for photocatalytic reduction of CO₂ and oxidation of H₂O. Under the conditions of visible light and a gas–solid system without a co-catalyst, a photosensitizer and a sacrificial agent, the yield of CO₂ reduction by TPVT-MOFs@g-C₃N₄-10 can reach 56.4 μmol·g⁻¹·h⁻¹, which is 3.2 times that of pure g-C₃N₄ (17.5 μmol·g⁻¹·h⁻¹). The results of DFT calculations showed that the adsorption of H₂O on the TPVT-MOFs@g-C₃N₄ composite material was more preferential, which promoted the adsorption and reduction of CO₂.