Fabrication of Rice-Like Porous Anatase TiO2 with High Thermal Stability and Enhanced Photocatalytic Performance

Rice-like porous anatase TiO2 with high crystallinity has been successfully synthesized by means of a facile hydrothermal method with the inorganic precursor titanyl sulfate, followed by calcination at higher temperature. The structures of the prepared TiO2 nanocrystals are characterized in detail by using XRD, Raman spectra, N2 adsorption/desorption isotherms, X-ray photoelectron spectroscopy, SEM, and TEM. Experimental results indicate that the anatase crystalline structure could be maintained up to 800 degrees C, which is attributed to the protection of S-containing species that are produced in situ during the hydrolysis of titanyl sulfate. They hinder the undesirable grain growth and aggregation, inhibit the anataserutile phase transformation, and protect the porous structure from collapse during the calcination process. The rice-like porous anatase TiO2, after calcination at 700 degrees C, exhibits better photocatalytic activity than Degussa P 25 TiO2 in the degradation of highly toxic 2,4-dichlorophenol under UV light irradiation. This improvement was attributed to the porous structure, which offers more active sites and facilitates mass transport, and the high crystallinity that favors the separation of photogenerated electronhole pairs, which is confirmed by analysis of surface photovoltage spectra.