Photocatalytic carbon dioxide (CO2) conversion to chemicals and fuels has gained significant consideration in industrial and scientific research. In this study, photocatalytic CO2 reduction to fuels over Cu-loaded graphitic carbon nitride (g-C3N4) under visible light irradiation has been investigated. The photocatalysts, synthesized by pyrolysis and impregnation method, were characterized by X-ray diffraction (XRD) Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM). Interestingly, CO2 was efficiently converted to CH4 and CH3OH with smaller amounts of C2H4 and C2H6 hydrocarbons. The yield of CH4 evolution as the main product over 3 wt. % Cu/g-C3N4 was 217.8 µmole/g.cat under visible light irradiation, significantly higher than the amount of CH4 produced over the pure g-C3N4 catalyst (119 µmole/g.cat). The enhancement was attributed to charge transfer property and suppressed recombination rate by Cu-metal. The Cu-metal loaded into g-C3N4 enhanced CO3 reduction efficiency for CH4 production while the pure g-C3N4 was promising for both CH4 and CH3OH production. The single step conversion of CO2 to CH4 and CH3OH with appreciable amount of hydrocarbons under solar energy registered good photo-activity and selectivity of Cu/g-C3N4 catalyst. A photocatalytic reaction mechanism was proposed to corroborate with the experimental results over the Cu-loaded g-C3N4 photocatalyst.
