Solvent-free in situ synthesis of g-C3N4/{001}TiO2 composite with enhanced UV- and visible-light photocatalytic activity for NO oxidation

Many possible applications of anatase TiO2 nanosheets with exposed {0 01} facets ({0 01}TiO2) are limited by its low quantum efficiency and no-spectral response in the visible region. We report on a simple solvent-free in situ method for synthesizing g-C3N4/{001}TiO2 composite that over comes these drawbacks. The in situ growth of g-C3N4 and the removal of F- ions on the {0 0 1}TiO2 surface that remain from the synthesis process were simultaneously achieved during the calcination of a mixture of prepared {0 0 1}TiO2 and urea, resulting in a compact connection between the two components, which facilitated the interfacial charge transfer process. The growth of g-C3N4 during the calcination process preserved the {0 0 1} facets of TiO2. The composite samples exhibited higher photocatalytic activity than either the pure g-C3N4 or {0 0 1}TiO2 nanosheets separately. Specifically, as measured by the removal of NO, the optimal composite sample, with a g-C3N4 content of 10%, was 2.4 times more effective than pure {0 0 1}TiO2, 4.1 times more effective than g-C3N4 under UV light, and 5.8 times more effective than g-C3N4 under visible light irradiation. Also, the composite prepared by this method showed much higher activity than similar composites that were prepared by evaporation and mechanical methods. The new method is simple and holds the promise of expanded large-scale production and wider use of {0 0 1}TiO2 based catalysts in the future. (C) 2015 Elsevier B.V. All rights reserved.