Green synthesis of methanol by photocatalytic reduction of CO2 under visible light using a graphene and tourmaline co-doped titania nanocomposites

Abstract In this work, we studied the effect of tourmaline percent on the photocatalytic activity of mesoporous TiO2–graphene. To evaluate and compare the physical properties of the prepared materials, X-ray diffraction analysis, BET measurements, UV–vis spectroscopy, PL spectroscopy, and TEM were applied. To determine the photocatalytic efficiency of the prepared materials, the photocatalytic reduction of CO2 was evaluated. The results indicate that tourmaline particles can obviously influence the structures of TiO2 and enhance photocatalytic activity due to their spontaneous permanent polarity. The quantum yield (QE) of the TiO2; G (1%)–TiO2; TG (1%)–TiO2; G (1%)–T (1%)–TiO2; G (1%)–T (1.5%)–TiO2; G (1%)–T (2%)–TiO2; G (1%)–T (2.5%)–TiO2; and G (1%)–T (3%)–TiO2 is 0.0049; 0.0178; 0.0357; 0.0580; 0.0670; 0.0922; 0.1072; and 0.1012 µmol g−1 h−1, respectively. Moreover, the excellent photocatalytic activity of the composites was fully maintained after six photocatalytic cycles, which may be attributed to the physicochemical property of tourmaline, graphene and the mixed-phase of anatase and brookite in the graphene and tourmaline co-doped titania composite.