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Abstract: Cerium doped TiO2-based nanosheets (Ce-TNSs) photocatalysts were prepared by a one-pot hydrothermal method using cerium nitrate as the cerium precursor. The photocatalysts were characterized by high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman spectra, ultraviolet–visible light diffuse reflectance spectra (DRS), X-ray photoemission spectroscopy (XPS) and fluorescence spectra (FL). The results show that Ce3+ and Ce4+ co-exist in Ce-TNS. The doping leads to changes in binding energies of Ti and O. The concentration of Ti3+ increases gradually when the cerium doping amount keep increasing. Appropriate amount of cerium doping can significantly inhibit the recombination of electron–hole pairs, which is proved by the decline in the intensity of the fluorescence spectra. Ce-TNS with doping ratio of 0.5% (molar ratio) possesses the highest photocatalytic activity when degrading Rhodamine B (RhB), which is 5 times and 1.6 times of that of P25 and the undoped TNS, respectively. It is suggested that cerium ions are efficient electron trappers to improve the separation efficiency of electrons and holes. [Copyright &y& Elsevier]

Abstract: TiO2-based nanosheet (TNS) was prepared by the alkaline hydrothermal treatment of P25, which was characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption–desorption measurement. Its adsorption and regeneration properties for removal of high-chroma crystal violet (CV) were systematically investigated. The prepared TNS has much higher specific surface area of 207m2/g and exhibits much stronger adsorption for CV than the raw material P25. The maximum adsorption capacity of TNS as determined from the Langmuir isotherm is 56.3mg/g. The enhancement of adsorption capacity is ascribed to the increasing of specific surface area and surface hydroxyl groups, which can provide much more adsorption sites and stronger electrostatic attraction. It was further found that H2O2 can produce a synergetic photocatalytic degradation effect with TNS under UV–Vis irradiation, and the regeneration of TNS was effectively achieved by H2O2-assisted photocatalytic degradation process. The good reusability of prepared TNS in the cyclic adsorption–regeneration experiments indicates that it may be useful for dealing with dye wastewater. [Copyright &y& Elsevier]

Abstract: TiO2-based nanosheet (TNS) was modified with Ag2O, and the adsorption and photocatalytic performances of modified nanosheet were characterized by the removal of high-concentration methylene blue (MB). When TNS was loaded with a proper amount of Ag2O, the adsorption capacity is enhanced to 2.2 times, with a maximum of 172.4mg/g determined from Langmuir isotherm. The adsorption results also show that a small amount of Ag2O-modified TNS can quickly enrich large amounts of MB molecules onto its surface via adsorption. Furthermore, Ag2O-modified TNS exhibits novel separation efficiency of photogenerated carriers evidenced by photoluminescence measurements, and enhanced photocatalytic activity proved by the degradation of MB. The good reusability of Ag2O-modified TNS implies a potential application for dealing with high-concentration dyes by adsorption–photocatalytic degradation. [Copyright &y& Elsevier]