Xiaowang Lu

In situ fabrication of Ce1−xLaxO2−δ/palygorskite nanocomposites for efficient catalytic oxidation of CO: effect of La doping

Novel palygorskite (PG) supported Ce1−xLaxO2−δ nanocomposites were prepared by a facile in situ deposition method using hexamethylenetetramine as the precipitant. The textural and structural properties of the products were characterized by XRD, HRTEM, FT-IR, Raman, XPS and TPR techniques. The results indicated that the oxide particles with an average size of about 5 nm were loaded successfully onto the surface of PG rods and were uniformly dispersed. The catalytic activities of Ce1−xLaxO2−δ/PG (x from 0.1 to 0.9) for CO oxidation were investigated. La3+ doping was found to have critical effects on the CO oxidation activity. The best Ce1−xLaxO2−δ/PG nanocomposite was obtained when the x value was adjusted to 0.5, and the reaction rate was found to be three times higher than that of a commercial CeO2 catalyst. Adequate introduction of La3+ promotes the formation of non-stoichiometric Ce1−xLaxO2−δ and is responsible for the formation of oxygen vacancies and surface superoxide ions. However, when the doping ratio increases to 0.6 or higher, co-precipitation of La2O3 leads to decreased redox properties and CO oxidation activity.

Sol–gel synthesis and catalytic property of Ce 1− x Ti x O 2 nanocomposites supported on attapulgite clay

Ce1−xTixO2 nanocomposites supported on attapulgite clay (Ce1−xTixO2/ATP) were prepared by a facile sol–gel route. The textural and structural properties of the prepared products were characterized by thermogravimetric-differential scanning calormetry analysis, X-ray diffraction, transmission electron microscopy, energy-dispersive spectrometry, Fourier transform infrared spectroscopy and Nitrogen adsorption-desorption measurements. The catalytic activity of the prepared Ce1−xTixO2/ATP catalysts for rhodamine B degradation was investigated. Results indicate that the particle size of Ce1−xTixO2 nanoparticles evenly attached onto the surface of ATP is approximately 10xa0nm. The Ti4+ doping ratios exhibit considerable impact on the redox ability and catalytic activity of Ce1−xTixO2/ATP composites. The introduction of an optimal amount of Ti4+ contributes to forming structure defects and electronic defects in the oxide lattice, increasing concentration of oxygen vacancies, consequently improving low-temperature redox ability of Ce4+ and enhancing catalytic activity of the composites. Ce1−xTixO2/ATP (xxa0=xa00.5) catalyst has the best catalytic degradation efficiency, which can reach as high as 97xa0% after reaction for 240xa0min. It is also found that attapulgite clay exhibit a positive synergistic effect to the Ce1−xTixO2 nanoparticles.

Black phosphorus quantum dots/attapulgite nanocomposite with enhanced photocatalytic performance

Novel black phosphorus quantum dots/attapulgite (BPQDs/ATP) nanocomposites were prepared via a facile hydrothermal-deposition method. TEM showed that BPQDs dispersed evenly on the surface of ATP with uniform particle size about 5nm. UV-Vis revealed that the BPQDs/ATP composite showed wider visible light absorption range as compared with pure ATP. The photocatalytic activity was evaluated by degradation of bisphenol A (BPA). Results showed that BPQDs/ATP reached 90% degradation rate under solar light irradiation for 180min. The coherent heterostructure formed by BPQDs and ATP was responsible for the enhanced photocatalytic performance, due to the sensitization effect of BPQDs and the facilitation of charges separation.

La1−xAgxFeO3/halloysites nanocomposite with enhanced visible light photocatalytic performance

AbstractnLa1−xAgxFeO3/halloysites nanotubes (HNTs) nanocomposite was synthesized by sol–gel method. It was characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectroscopy and UV–visible diffused reflectance spectroscopy measurements. The photo-activity of the La1−xAgxFeO3/HNTs nanocomposite was evaluated via degradation of methylene blue (MB) under visible-light irradiation. The results showed that the HNTs with unique pore structure favored the adsorption of organic molecules. Adequate Ag+ doping improved the absorption ability for visible light. The La0.95Ag0.05FeO3/HNTs demonstrated the best photocatalytic performance, which achieved as high as 99xa0% for MB degradation exposed 2xa0h irradiation. However,further increasing of Ag+ doping gradually reduced the photocatalytic activity. The nanocomposite catalyst showed outstanding recyclability after eight cycles which still remained up to 90xa0%.

Sol–gel Synthesis of LaBO 3 /Attapulgite (B=Mn, Fe, Co, Ni) Nanocomposite for NH 3 -SCR of NO at Low Temperature

LaBO3/attapulgite (ATP) (B=Mn, Fe, Co, Ni) composites were prepared by sol–gel method using citric acid as complex agent. The products were characterized by X-ray diffraction transmission electron microscopy, energy-dispersive spectroscopy, Battett–Emmett–Teller, fourier-transform infrared, H2 temperature-programmed reduction and temperature-programmed desorption of NH3 measurements. The catalytic activity of LaBO3/ATP nanocomposites was evaluated via selective catalytic reduction of NO with NH3 by fixed bed denitration equipment at low-temperature. The impact of the various B-site elements on the NO conversion was investigated. Results showed that the adsorption capacity of NH3 played significant role in the low temperature denitrification process, and Mn was the best B-site element where LaMnO3/ATP achieves 81% conversion of NO at 250xa0°C.

Carbon quantum dots/attapulgite nanocomposites with enhanced photocatalytic performance for desulfurization

Carbon quantum dots (CQDs)/attapulgite (ATP) nanocomposite was prepared by a simple impregnation method. The ATP was initially modified with hydrochloric acid solution, which favored for the combination of CQDs due to the generation of hydroxyl group on the surface. XRD shows the decrease of interplanar spacing of ATP (1 1 0) plane, suggesting that the CQDs are immobilized on the surface of ATP. UV–Vis shows that the absorption peak of modified ATP is apparently red-shifted and the absorbance intensity of CQDs/ATP is higher than others. FT-IR and XPS show that the CQDs are immobilized on the surface of ATP through hydroxylation reaction. TEM shows that the average diameter of CQDs nanoparticles is about 5xa0nm and they are coated on the surface of ATP uniformly. The CQDs/ATP nanocomposite was employed as catalyst for photocatalytic degradation of dibenzothiophene (DBT) in model gasoline under visible light irradiation. The influence of the mass ratio of CQDs to ATP on desulfurization performance was investigated. The desulfurization rate of DBT could reach 93% when the mass ratio of CQDs/ATP is 3:10. The enhanced photocatalytic oxidative desulfurization was attributed to the sensitizing effect and up-conversion property of CQDs.