Sorbitol-employed hydrothermal carbonization to TiO2@C mesoporous hybrids with promoted visible light utilization and excellent photosensitization stability

Abstract Rational design of carbonaceous TiO2 hybrids materials is attracting increasing interest because TiO2 is regarded as a promising non-toxic, stable, and cheap photocatalyst for environmental remediation. In this work, mesoporous TiO2@C (sorbitol-carbon) hybrids were successfully synthesized by hydrolysis of titanium glycolate precursor and hydrothermal carbonization of sorbitol molecules. It was found that the sorbitol-mediated hydrothermal carbonization process not only provides the carbon component, but also induces the formation of mesoporous nanostructures of TiO2. The UV–vis diffuse reflectance spectra showed that carbonaceous materials enhance the visible light absorption of TiO2 materials. The involvement of sorbitol-carbon along with the large surface area can promote the adsorption capability of this photocatalyst towards rhodamine B dye and subsequently improves the dye sensitization process. On the basis of the electrochemical results, the sorbitol-carbon coating on the TiO2 is conducive to a rapid charge transfer process and responsible for the enhanced photosensitized photocatalysis. The high-resolution mass spectra indicated that the possible degradation mechanism of RhB in the presence of TiO2@C hybrids included three processes: de-ethylation, opening-ring, and mineralization, which coexisted in visible-light-induced photocatalytic system. It is expected that this work will opens the way towards efficient fabrication of carbonaceous photocatalysis materials using sorbitol for photosensitization degradation of dyes under visible light irradiation.