Surface modified C, O co-doped polymeric g-C3N4 as an efficient photocatalyst for visible light assisted CO2 reduction and H2O2 production

Mimicking the artificial photosynthesis utilizing solar energy for the production of hydrocarbon fuel is a sustainable strategy to tackle the fossil fuel-based energy crisis. Herein, a surface-modified g-C3N4 was synthesized by the co-condensation of urea + thiourea and 2-methyl imidazole. Physicochemical characterizations reveal that O and C are co-doped, as evident by the XPS and solid-state NMR spectroscopy. The light absorption edge is red shifted, lifetimes of the charge carriers, and electron injection efficiencies are ameliorated appropriately. Photocatalysts are employed in the CO2 reduction (from TEOA dissolved water + CO2 gas mixture) and H2O2 production (from pure H2O and O-2 in absence of any organic electron/proton donor) without involving any cocatalyst. CO2-adsorption/TPD measurements support the higher CO2 uptake and lower adsorption energy after the surface modification as confirmed from DFT calculation. Mott-Schottky and VBXPS confirm that C, O co-doping bring required thermodynamic potential that facilitates the CO2/CH3OH and O-2/H2O2 reactions.