Photocatalytic conversion of carbon dioxide to methanol over different precursors of graphitic carbon nitride supported on fibrous silica iron

Abstract

In this study, the graphitic carbon nitride (g-C3N4) was successfully synthesized through thermal polymerization under three different g-C3N4 precursors such as urea (U-gC3N4), melamine (M-gC3N4) and dicyandiamide (D-gC3N4) and then doped into the fibrous silica iron (FSFe), denoted as U-gC3N4/FSFe, MgC3N4/FSFe, and D-gC3N4/FSFe, respectively. The synthesized catalysts were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis/DRS) and also tested for photocatalytic conversion of carbon dioxide (CO2) to methanol (CH3OH). The study indicated that altering the precursors had a substantial impact on the physicochemical features of the FSFe, which in turn increased the catalytic performance of the conversion of CO2 to CH3OH. U-gC3N4/FSFe exhibits the highest CH3OH yield (2.3 x 104 µmol gcat−1) compared to bare FSFe, D-gC3N4/FSFe and M-gC3N4/FSFe under visible light irradiation within 240 min. The higher CH3OH yield over U-gC3N4/FSFe is mostly owing to the lower bandgap energy of U-gC3N4/FSFe, as well as the advantageous interaction between g-C3N4 and FSFe.