Fabrication of TiO2-doped single layer graphitic-C3N4 and its visible-light photocatalytic activity

In this work, TiO2-doped single layer graphitic carbon nitride (TiO2/SL g-C3N4) was successfully prepared by a facile stirring and calcination route. The as-prepared TiO2/SL g-C3N4 photocatalysts were systematically characterized to elucidate their morphologies, chemical and photocatalytic properties. The obtained anatase TiO2 nanoparticles dispersed well on the surface of the single layer g-C3N4 sheets. TiO2/SL g-C3N4 displayed increased visible light absorption with a certain extent red-shift of the absorption edge to visible region as compared to pure TiO2. Under visible light irradiation, the optimal TiO2/SL g-C3N4 (the mass ratio of TiO2 and SL g-C3N4 to be 1:5) exhibited enhanced photocurrent response, achieving a photocurrent approximately 2-times higher than SL g-C3N4. All the TiO2/SL g-C3N4 samples had enhanced photodecomposition performance than pure TiO2 or SL g-C3N4. The pseudo-first-order kinetic constant of Rhodamine B (RhB) decomposition on optimal TiO2/SL g-C3N4 was 3.4 times as great as that of pure SL g-C3N4 under the conditions of visible light irradiation with light wavelength more than 400 nm and 150 min treatment after 30 min adsorption equilibrium. The excellent photocatalytic performance TiO2/SL g-C3N4 under visible light irradiation mainly benefited from enhanced separation of photo-generated electron-hole pairs as well as the extended optical absorption edge. Active species trapping experiments indicated that h+ played crucial role in photocatalytic process and a possible mechanism for the improved photocatalytic activity was proposed.