Synthesis of C-doped TiO2 by sol-microwave method for photocatalytic conversion of glycerol to value-added chemicals under visible light

Abstract C-doped TiO2 photocatalyst synthesized using a one-step sol-microwave method with microcrystalline cellulose as the carbon source to achieve TiO2 of desirable visible light absorption, cluster size, surface area and band gap was applied in the photocatalytic oxidation of glycerol under visible light to produce value-added chemicals, for the first time. An increase in microwave irradiation time from 0 to 20 min reduced the anatase crystal size but increased the surface area, pore volume and pore radius. Carbon coupled with microwave treatment produced Ti3+ and oxygen vacancies in the TiO2 lattice of the C-doped TiO2 which yielded improved performance of the photocatalysts. For example, a cellulose loading at 10 % (i.e. 10 % Cel-TiO2(4-MW)) provided the highest photo-conversion of glycerol (67.5 %) and highest yields of glyceraldehyde (10.0 %), dihydroxyacetone (7.4 %), formic acid (49.0 %) and acetic acid (1.8 %). On the other hand, excess residual carbon on TiO2 surface (e.g. 20 % Cel-TiO2(0-MW)) retarded the activity of the photocatalyst.