pThe UV–vis diffuse reflection spectra (DRS) were obtained for thedry-pressed disk samples on a UV-Vis spectrophotometer (UV-3600) using BaSO4as the reference. Raman spectra were recordedon a laser micro-Raman spectrometer (Invia, Renishaw). Fouriertransform infrared spectroscopy (FT-IR) spectra were obtained on aNicolet iS10 spectroscope to investigate the surface organic specieson TiO2.2.3. Photoelectrochemical measurement and•OH trappingPhotocurrents were measured on an electrochemical analyzer(CHI 660C) in a standard two-electrode system with the as-prepared samples as the working