Effect of g-C3N4 loading on TiO2-based photocatalysts: UV and visible degradation of toluene

g-C3N4 was introduced into a highly active anatase TiO2-based photocatalyst using a simple yet effective impregnation method. The corresponding composite materials were obtained with a carbon nitride weight content ranging from 0.25 to 4 wt.%, and their surface, morphological and structural properties were characterized using BET and porosity measurements, X-ray diffraction, infrared, UV-vis and photoluminescence spectroscopy, and transmission electron microscopy. They were subsequently tested for toluene photoelimination under UV and sunlight-type illumination conditions. The photocatalytic performance of the materials was analysed quantitatively through calculation of the quantum yield of the reaction under all illumination conditions essayed. We observed that the addition of carbon nitride enhances the photoactivity and selectivity to CO2 of samples containing 0.5 to 1 wt.% g-C3N4. Physicochemical characterization presented evidence that the enhanced behaviour is related to the intimate contact between the two components of the photocatalyst system, which provides two new (i.e. not present in the parent system) charge carrier handling routes affecting photocatalytic properties upon UV and visible light illumination.