La/WO3 system were successfully built via a simply crystallization precipitation method using sodium tungstate and lanthanum nitrate hexahydrate as precursor. Samples were characterized by powder X-ray diffraction, UV–Vis absorbance spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and N2 adsorption–desorption isotherms (BET). Results showed that La does not enter into the crystal lattice of WO3 but located in the interstitial site and accordingly presented as the form of La–O–W in the interstitial site. In addition, doping of La restrict the grain size and the minimum crystal size was 28 nm at La:W = 3:10. Photocatalytic degradation of Rhodamine B showed that the modified samples had better catalytic performance. When La:W reaches 0.3, the La/WO3 nano-materials exhibits the highest photocatalytic activity, which can be attributed to the synergic effect of the higher BET surface area, surface hydroxyl content and optimum La contents. A possible mechanism for the photocatalytic degradation of RhB has also been provided.

A series of TiO2 nanosheets are prepared with different amounts of AgNO3 and HF solution through a solvothermal process. The samples are characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), laser Raman spectroscopy (LRS), electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). From the results it is clear that the added HF solution inhibits the crystallite size growth in the [001] direction, and induces the formation of the TiO2 nanosheets with highly exposed (001) facets. There is a strong interaction between the Ag nanoparticles and the TiO2 support. The (Ag,F)-modified TiO2 catalyst exhibits high activity of MB photodegradation under both UV light and visible light irradiation. Two mechanisms of photocatalysis under UV light and visible light irradiation were discussed and proposed. It is indicated that the strong interaction between the Ag nanoparticles and the TiO2 support improves the photocatalytic activity of TiO2 nanosheets.

Even though heteroepitaxial growth of one-dimensional microstructures or three-dimensional islands has been realized via strategies such as chemical vapor deposition, molecular beam epitaxy, and solution phase, researchers have not succeeded in the formation of one-dimensional hybrid microstructures via the combination of heteroepitaxial growth and oriented dissolution up to now. In this work, well ordered single crystalline calcium-doped strontianite–calcite hybrid micropillar arrays with the long axis along the [001] direction of the two phases were formed on calcite (104) substrates via heteroepitaxial growth of strontianite and oriented dissolution of calcite in aqueous solution for the first time. Energy-dispersive spectroscopy analysis shows that the micropillars are composed of strontianite occluded with about 12 mol % of Ca. During the growth process of strontianite, calcite cores formed in the inner side of the strontianite micropillars at the base stage via the oriented dissolution. The lattices of the strontianite and calcite match very well at the interface of calcite and strontianite. A novel formation mechanism is proposed for the formation of Ca-doped strontianite–calcite hybrid micropillars via the synergetic process of the oriented dissolution of one carbonate mineral and the heteroepitaxial growth of another carbonate mineral in Volmer–Weber growth mode with a small lattice misfit. Ca-doped strontianite micropillar arrays might grow epitaxially on the calcite (001) and (104) planes with small misfits.

This work is mainly focused on the investigation of the influence of the amount of a few CeO2 on the physicochemical and catalytic properties of CeO2-doped TiO2 catalysts for NO reduction by a CO model reaction. The obtained samples were characterized by means of XRD, N2-physisorption (BET), LRS, UV-vis DRS, XPS, (O2, CO, and NO)-TPD, H2-TPR, in situ FT-IR, and a NO + CO model reaction. These results indicate that a small quantity of CeO2 doping into the TiO2 support will cause an obvious change in the properties of the catalyst and the TC-60:1 (the TiO2/CeO2 molar ratio is 60:1) support exhibits the most extent of lattice expansion, which indicates that the band lengths of Ce–O–Ti are longer than other TC (the solid solution of TiO2 and CeO2) samples, probably contributing to larger structural distortion and disorder, more defects and oxygen vacancies. Copper oxide species supported on TC supports are much easier to be reduced than those supported on the pure TiO2 and CeO2 surface-modified TiO2 supports. Furthermore, the Cu/TC-60:1 catalyst shows the highest activity and selectivity due to more oxygen vacancies, higher mobility of surface and lattice oxygen at lower temperature (which contributes to the regeneration of oxygen vacancies, and the best reducing ability), the most content of Cu+, and the strongest synergistic effect between Ti3+, Ce3+ and Cu+. On the other hand, the CeO2 doping into TiO2 promotes the formation of a Cu+/Cu0 redox cycle at high temperatures, which has a crucial effect on N2O reduction. Finally, in order to further understand the nature of the catalytic performances of these samples, taking the Cu/TC-60:1 catalyst as an example, a possible reaction mechanism is tentatively proposed.

La3+-doped CeO2-γ-Al2O3 intergrowth mixed oxide powders were synthesized using an improved amorphous citric precursor (IACP) method and then steam-aged with 90% steam and 10% air for 12 h at 788 °C. The synthesized materials were characterized through X-ray diffraction, energy-dispersive X-ray spectrometry, H2 temperature programmed reduction, Brunauer–Emmett–Teller, and oxygen storage/release capacity (OSC) measurements. La3+ was successfully doped into the CeO2-γ-Al2O3 lattice to form an intergrowth system. Strong intergrowth interactions were observed between CeO2, La2O3, and γ-Al2O3 crystallites. The (Ce0.92La0.08)0.4Al0.6O2−z(CLA) sample showed a maximum OSC of 979 μmol g−1; however, the pure ceria sample showed a low OSC of 315 μmol g−1. The CLA samples maintained a relatively high OSC of 880 μmol g−1 even after hydrothermal treatment. These results may be attributed to the incorporation of La3+ ions into the ceria lattice to form a CeO2–La2O3 solid solution as well as to the intergrowth interactions between the CeO2–La2O3 solid solution and γ-Al2O3. Such interactions affected structural homogeneity and oxygen vacancy formation and inhibit the CLA particles from sintering during steam-aging.

The intergrowth of mixed oxides CuO and γ-Al2O3 have strong mutual interactions, and their microstructures are modified. There are alternating positive and negative charges in the γ-Al2O3 crystallite. Simultaneously, one kind of Cu–O bond length becomes longer. These two effects result in the intergrowth mixed oxides having a higher CO catalytic oxidation performance.

•CdTe/Y nanocomposites were synthesized via a novel approach in an aqueous medium.•The CdTe Quantum Dots Encapsulated in Zeolite Y were more regular and stable.•CdTe/Y nanocomposites exhibit a high catalytic performance by the photocatalytic degradation of methyl blue.A series of CdTe/Y nanocomposites was prepared by introducing Cd2+ into zeolite Y and then adding TeO2 and NaBH4. X-ray diffraction and Fourier-transform infrared spectroscopy analysis showed that the framework structure of zeolite Y was not destroyed and that CdTe quantum dots were successfully introduced into zeolite Y. Ultraviolet–visible diffused reflectance spectroscopy demonstrated that the absorption spectra of CdTe/Y evidently red shifted compared with zeolite Y. The effect of the initial Cd2+ concentration was systematically investigated. The photocatalytic activities of CdTe/Y were also measured by the photocatalytic degradation of methyl blue. Results indicated that CdTe/Y had high catalytic performance and that photocatalytic activity increased with increased Cd2+ concentration.

•Influence of TiO2 structure on CuO/TiO2 catalysts.•These are a lot of Cu+ ions and oxygen vacancies that exist on CuO/TiO2 (rutile) catalyst.•CuO/TiO2 (rutile) catalyst is readily reduced.•CO species can adsorb to form Cu+ (CO)2 and O2 can adsorb to form O2−.The present work tentatively investigated anatase- or rutile-supported copper oxide catalysts. 5% copper oxide can be well dispersed on anatase or rutile surfaces. The copper oxide dispersed on rutile surface exists in Cu2+ and Cu+ ions, which is more readily reduced, and show higher catalytic activity of CO oxidation. The mechanism of CO oxidation over rutile support is different from anatase support.Download full-size image

This work is mainly focused on the investigation of the influence of the amount of a few CeO2 on the physicochemical and catalytic properties of CeO2-doped TiO2 catalysts for NO reduction by a CO model reaction. The obtained samples were characterized by means of XRD, N2-physisorption (BET), LRS, UV-vis DRS, XPS, (O2, CO, and NO)-TPD, H2-TPR, in situ FT-IR, and a NO + CO model reaction. These results indicate that a small quantity of CeO2 doping into the TiO2 support will cause an obvious change in the properties of the catalyst and the TC-60:1 (the TiO2/CeO2 molar ratio is 60:1) support exhibits the most extent of lattice expansion, which indicates that the band lengths of Ce–O–Ti are longer than other TC (the solid solution of TiO2 and CeO2) samples, probably contributing to larger structural distortion and disorder, more defects and oxygen vacancies. Copper oxide species supported on TC supports are much easier to be reduced than those supported on the pure TiO2 and CeO2 surface-modified TiO2 supports. Furthermore, the Cu/TC-60:1 catalyst shows the highest activity and selectivity due to more oxygen vacancies, higher mobility of surface and lattice oxygen at lower temperature (which contributes to the regeneration of oxygen vacancies, and the best reducing ability), the most content of Cu+, and the strongest synergistic effect between Ti3+, Ce3+ and Cu+. On the other hand, the CeO2 doping into TiO2 promotes the formation of a Cu+/Cu0 redox cycle at high temperatures, which has a crucial effect on N2O reduction. Finally, in order to further understand the nature of the catalytic performances of these samples, taking the Cu/TC-60:1 catalyst as an example, a possible reaction mechanism is tentatively proposed.