Well-designed glucose precursor carbon/g-C₃N₄ nanocomposite for enhanced visible light photocatalytic CO₂ reduction activity

Fabrication of glucose precursor carbon-doped g-C₃N₄ nanocomposite (C/g-C₃N₄) for enhancing photocatalytic CO₂ reduction into syngas (CO, CH₄) has been investigated. The samples were successfully synthesized via a two-step thermal treatment and tested in a fixed bed reactor under visible light. The 0.2 % glucose precursor carbon-doped over g-C₃N₄ photocatalyst has demonstrated excellent activity in converting CO₂ to CO and CH₄ under visible light. The main product yield, CO of 898.9 μmol g-cat⁻¹ was produced over 0.2 % C/g-C₃N₄, which is 4.6 folds the amount of CO obtained over the g-C₃N₄ (196.8 μmol g-cat⁻¹). The XPS results confirmed the formation of a C-O-C bond between carbon and g-C₃N₄, resulting in a strong interaction between carbon and g-C₃N₄. Carbon-doped g-C₃N₄ possesses a narrow energy band and the ability to effectively absorb solar light, which enables efficient transportation of electrons generated by photon excitation. Possible reaction mechanisms for photoreduction of CO₂ over carbon-doped g-C₃N₄ photocatalyst were proposed in order to understand the movement of electrons and holes. This work provides a simple method for designing highly efficient carbon-based photocatalysts for potential application in photocatalytic CO₂ reduction using solar energy.