Ze-Da Meng

Synthesis of fullerene modified with Ag2S with high photocatalytic activity under visible light

We improve the photocatalytic effect of Ag2S under visible light by using fullerene modified with Ag2S nanoparticles. Surface areas and pore volumes of the Ag2S–fullerene samples showed catastrophic decreases due to the deposition of Ag2S. The generation of reactive oxygen species was detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the photocatalytic effect increase in the case with the modified fullerene. In comparison with the separate effects of Ag2S and fullerene nanoparticles, the photocatalytic effect of the fullerene modified with Ag2S composites is increased significantly due to the synergetic effect between the fullerene and the Ag2S nanoparticles.

Enhanced Sonocatalytic Degradation of Rhodamine B by Graphene-TiO2 Composites Synthesized by an Ultrasonic-Assisted Method

Abstract A series of graphene-TiO2 composites was fabricated from graphene oxide and titanium n-butoxide (TNB) by an ultrasonic-assisted method. The structure and composition of the nanocomposites were characterized by Raman spectroscopy, BET surface area measurements, X-ray diffraction, transmission electron microscopy, and ultraviolet-visible absorption spectroscopy. The average size of the TiO2 nanoparticles on the graphene nanosheets was controlled at around 10–15 nm without using surfactant, which is attributed to the pyrolysis and condensation of dissolved TNB into TiO2 by ultrasonic irradiation. The catalytic activity of the composites under ultrasonic irradiation was determined using a rhodamine B (RhB) solution. The graphene-TiO2 composites possessed a high specific surface area, which increased the decolorization rate for RhB solution. This is because the graphene and TiO2 nanoparticles in the composites interact strongly, which enhances the photoelectric conversion of TiO2 by reducing the recombination of photogenerated electron-hole pairs.

The characteristic study and sonocatalytic performance of CdSe–graphene as catalyst in the degradation of azo dyes in aqueous solution under dark conditions

The sonocatalytic degradation of azo dyes; methyl orange (MO) and rhodamine B (RhB) were studied catalyzed by cadmium selenide (CdSe)-graphene in dark ambiance. The CdSe-graphene composites were prepared by simple hydrothermal method. The characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), specific surface area (BET) and with energy dispersive X-ray (EDX). The UV-spectroscopic analysis of the dyes was done by measuring the change in absorbance. The degradation of the organic dyes was calculated based on the decrease in concentration of the dyes with respect to regular time intervals. The rate coefficients for the sonocatalytic process were successfully established and the reusability tests were done to test the stability of the used catalysts.

Effect of Pt treated fullerene/TiO2 on the photocatalytic degradation of MO under visible light

Platinum treated fullerene/TiO2 composites (Pt-fullerene/TiO2) were prepared using a sol–gel method. The composite obtained was characterized by FT-IR, BET surface area measurements, X-ray diffraction, energy dispersive X-ray analysis, transmission electron microscopy (TEM) and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the Pt-TiO2, fullerene-TiO2 and Pt-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed and Pt-fullerene/TiO2 has the best photocatalytic activity, which may be attributable to increase of the photo-absorption effect by the fullerene and the cooperative effect of the Pt.

Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light

WO3-treated fullerene/TiO2 composites (WO3-fullerene/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the WO3-fullerene, fullerene-TiO2, and WO3-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed, and WO3-fullerene/TiO2 has the best photocatalytic activity; it may attribute to the increase of the photo-absorption effect by the fullerene and the cooperative effect of the WO3.

Characterization and relative sonocatalytic efficiencies of a new MWCNT and CdS modified TiO2 catalysts and their application in the sonocatalytic degradation of rhodamine B

TiO(2) nanoparticles modified with MWCNTs and CdS were synthesized by the sol-gel method followed by solvothermal treatment at low temperature. The chemical composition and surface structure of the CdS/CNT-TiO(2) composites were investigated by X-ray diffraction, specific surface area measurements, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. Then a series of sonocatalytic degradation experiments were carried out under ultrasonic irradiation in the presence of CNT/TiO(2) and the CdS/CNT-TiO(2) composites. It was found that RhB was quickly and effectively degraded under different ultrasonic conditions. As expected, the nanosized CdS/CNT-TiO(2) photocatalyst showed enhanced activity compared with the non CdS treated CNT/TiO(2) material in the sonocatalytic degradation of RhB. The sonocatalyst CCTb with 34.68% contents of Ti heat treated at 500 °C for 1h showed the highest sonocatalytic activity. The synergistic effect of the greater surface area and catalytic activities of the composite catalysts was examined in terms of their strong adsorption ability and interphase interaction by comparing the effects of different amounts of MWCNTs and CdS in the catalysts and their roles. The mechanism of sonocatalytic degradation over the CdS/CNT modified TiO(2) composites under different ultrasonic conditions was also discussed.

SYNTHESIS OF GRAPHENE-CDSE COMPOSITE BY A SIMPLE HYDROTHERMAL METHOD AND ITS PHOTOCATALYTIC DEGRADATION OF ORGANIC DYES

Abstract A graphene-CdSe composite was synthesized by a facile hydrothermal method, and characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy and UV-vis diffuse reflectance spectrophotometry. The graphene-CdSe composite efficiently catalyzed the photodegradation of methylene blue (MB), methyl orange (MO) and rhodamine B (Rh.B) in aqueous solution under UV or visible light irradiation. The graphene-CdSe composite exhibited a higher photocatalytic activity for the MB solution.

Synthesis of CdS/CNT-TiO2 with a high photocatalytic activity in photodegradation of methylene blue

Abstract Novel CdS/CNT-TiO 2 photocatalysts were synthesized by a simple chemical routine through the drop-wise addition of Na 2 S·5H 2 O solutions to cadmium acetate solutions containing purified multiwall carbon nanotubes (MWCNTs). The CdS/CNT materials obtained were treated with titanium (IV) n-butoxide to form CdS/CNT-TiO 2 composites which were characterized by N 2 adsorption, XRD, TEM, SEM, and energy-dispersive X-ray analysis. The composites were found to be porous, and the MWCNTs were homogenously dispersed in the composites without any apparent agglomeration of TiO 2 nanoparticles and CdS nanoparticles. The CdS/CNT-TiO 2 composites exhibited excellent activity for the degradation of methylene blue under UV and visible-light irradiation. This was attributed not only to the photocatalysis of the supported TiO 2 for the radical reaction and the adsorptivity of MWCNTs, but also to the introduction of the narrow-band gap semiconductor CdS that increases the transfer rate of photogenerated electrons through the surface of the MWCNTs.

Preparation of CuS-graphene oxide/TiO2 composites designed for high photonic effect and photocatalytic activity under visible light

CuS-graphene oxide/TiO2 composites were prepared using a sol-gel method to improve the photocatalytic performance of the photocatalyst. The composites were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible-light irradiation. The photodegradation of MB under visible-light irradiation reached 90.1% after 120 min. The kinetics of MB degradation was plotted alongside the values calculated from the Langmuir-Hinshelwood equation. The CuS-graphene oxide/TiO2 sample prepared using 0.2 mol of TiO2 showed the best photocatalytic activity. This was attributed to a cooperative reaction as a result of increased photoabsorption by graphene oxide and an increased photocatalytic effect by CuS.

Hydrothermal Synthesis of Porous Ag2S Sensitized TiO2 Catalysts and Their Photocatalytic Activities in the Visible Light Range

Abstract Porous Ag 2 S sensitized TiO 2 catalysts were synthesized by the hydrothermal process. The crystallization and porous structure of the Ag 2 S/TiO 2 composite photocatalysts were investigated by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, UV-Vis diffuse reflectance spectroscopy, and N 2 adsorption. The Ag 2 S/TiO 2 composites were mainly composed of anatase TiO 2 and acanthite Ag 2 S. The absorption edge wavelengths of TiO 2 and the Ag 2 S/TiO 2 composite prepared with 3 mmol Na 2 S·5H 2 O were 400 and 800 nm, respectively, that is, the absorption edge of the composite had a pronounced red shift. The photocatalytic activity under visible light was investigated by the degradation of methylene blue with a UV-Vis spectrophotometer. The photocatalytic activities under visible light of the Ag 2 S/TiO 2 photocatalysts were much higher than that of TiO 2 .