Construction of glucose precursor carbon/TiO₂ heterojunction with high ligand-to-metal charge transfer (LMCT) for visible light driven CO₂ reduction

Well-designed fabrication of glucose precursor carbon-doped TiO₂ heterojunction with high Ligand-to-Metal Charge Transfer (LMCT) for enhancing photocatalytic CO₂ conversion has been examined. Photocatalysts were fabricated using a single-step thermal method and tested in a fixed-bed reactor under visible light. The 6 % glucose precursor carbon-doped over TiO₂ (6 %C/TiO₂) photocatalyst has demonstrated excellent activity in converting CO₂ to CO and CH₄ under visible light. The main product yield, CO of 739.9 μmol g-cat⁻¹ was produced over 6 %C/TiO₂, which is 4.4 folds the amount of CO obtained over TiO₂ (168.7 μmol g-cat⁻¹). The XPS findings reveal the presence of different surface components containing C-OH, C[dbnd]C, and C[dbnd]O functional groups, which contribute to the formation of a ligand-metal-charge-transfer (LMCT) complex between carbon and TiO₂ photocatalyst. Carbon-doped TiO₂ possesses a narrow energy band and the ability to effectively absorb solar light, which enables efficient transportation of electrons generated by photon excitation. The mechanism of the carbon-doped TiO₂ in CO₂ conversion to CO and CH₄ is postulated to be consistent with the LMCT complex phenomena. Therefore, carbon-doped TiO₂ provides heterojunction for localization of electrons, impedes the rate at which charges recombine, and reduces the band gap energy, leading to improved photocatalytic performance when exposed to visible light.