Preparation and photocatalytic activity of TiO2–carbon surface composites by supercritical pretreatment and sol–gel process

TiO2–carbon surface composites (TCS) were prepared by supercritical pretreatment and then sol–gel process. The key factors affecting the methylene blue (MB) oxidation efficiency were investigated, including the initial concentration of MB, the pH value and the catalysts concentration. The results show that TCS have higher degradation efficiency than pure TiO2 and TiO2–carbon composites (TC) prepared by sol–gel process. The optimal conditions were a MB concentration of 20 mg/l at pH 6 with TCS concentration of 2.5 g/l for the fastest rate of MB degradation. Total organic carbon (TOC) analysis indicates complete mineralisation of MB.