Visible-light photocatalysts were prepared from TiC to create substitutional doped TiO2 of controlled carbon content. The conversion from TiC to c-doped TiO2 was monitored by in-situ X-ray diffraction and its bulk and surface compositions characterized by XRF, XPS and ToF-SIMS. The surface chemistry was further analyzed by FTIR and micro-Raman. The study established that the band gap can be deliberately shifted towards visible-light enabling activity tests on samples of discrete band gaps. Furthermore, the photocatalyst samples has relatively clean surface free of carbonaceous deposits. To investigate the role of surface chemistry on photocatalytic reaction, surface functionalities were introduced by grafting organic moieties with -COOH, -COH and –OH groups. The photocatalytic reaction was investigated for three model pollutants in water, a dye molecule (i.e., methylene blue), a refractory chemical (i.e., 1,2-dichlorophenol) and an endocrine disrupting compounds (i.e., dichlofenac sodium). C-doped TiO2 without surface functionalization is active only for methylene blue, but not for the two colorless pollutants (i.e., 1,2-chlorophenol and diclofenac sodium). Selectively introducing the –COOH, -COH and –OH functional moieties showed significant improvement in visible-light photocatalytic activity for all three pollutants. The surface functional moieties are believed to enhance surface hydrophilicity and improve OH- generation, while simultaneously retarding electron-hole recombination.

Role of surface chemistry on the photoactivity of C-doped TiO2 derived from TiC

249th National Meeting (2015)

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