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

In this study, the graphitic carbon nitride (g-C 3 N 4 ) was successfully synthesized through thermal polymerization under three different g-C 3 N 4 precursors such as urea (U-gC 3 N 4 ), melamine (M-gC 3 N 4 ) and dicyandiamide (D-gC 3 N 4 ) and then doped into the fibrous silica iron (FSFe), denoted as U-gC 3 N 4 /FSFe, MgC 3 N 4 /FSFe, and D-gC 3 N 4 /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 (CO 2 ) 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 CO 2 to CH 3 OH. U-gC 3 N 4 /FSFe exhibits the highest CH 3 OH yield (2.3 x 10 4 µmol gcat−1) compared to bare FSFe, D-gC 3 N 4 /FSFe and M-gC 3 N 4 /FSFe under visible light irradiation within 240 min. The higher CH 3 OH yield over U-gC 3 N 4 /FSFe is mostly owing to the lower bandgap energy of U-gC 3 N 4 /FSFe, as well as the advantageous interaction between g-C 3 N 4 and FSFe.