Ti3+ self-doped mesoporous black TiO2/SiO2/g-C3N4 sheets heterojunctions as remarkable visible-lightdriven photocatalysts

Ti3+ self-doped mesoporous black TiO2/SiO2/g-C3N4 sheets heterojunctions are successfully prepared by a solgel strategy, followed by calcination at 450 degrees C and hydrogenation at 500 degrees C. The characterization results indicate that Ti3+ self-doped mesoporous black TiO2/SiO2/g-C3N4 sheets heterojunctions photocatalysts possess high surface area of similar to 145.6 m(2) g(-1), large pore size of similar to 4 nm and pore volume of similar to 0.27 cm(3) g(-1), respectively. The complete retention of the mesoporous frameworks is attributed to the addition of SiO2, which not only retards the growth of TiO2 crystals but also avoids the collapse of the channels even under high temperature calcination process. The prepared heterojunctions photocatalysts with narrow bandgap of similar to 2.25 eV exhibit the excellent photocatalytic activity for degradation of phenol (98.5%), reduction of Cr6+ (97%) and photocatalytic hydrogen evolution (572.6 mu mol h(-1) g(-1)) under visible light irradiation, which is several times higher than that of pristine one. The outstanding photocatalytic property can be ascribed to the unique mesoporous framework enhancing the adsorption of pollutants and favoring the mass transfer, Ti3+ self-doping reducing the bandgap and extending the photoresponse to visible light region, the formation of heterojunctions preventing the recombination of photogenerated electrons and holes and benefiting their effective separation.