Enhanced photocatalytic reduction of Cr(VI) by ZnO–TiO2–CNTs composites synthesized via microwave-assisted reaction

ZnO–TiO2–carbon nanotubes (CNTs) composites are successfully synthesized using microwave-assisted reaction of ZnO precursor in TiO2 and CNTs suspension using a microwave synthesis system and they are used as photocatalysts for photocatalytic reduction of Cr(VI). The results show that the CNTs addition could enhance the photocatalytic performance of ZnO–TiO2 composites. The ZnO–TiO2 composites achieve a maximum reduction rate of 90% at 240 min under UV light irradiation, much higher than those for the pure ZnO (58%) and the ZnO–TiO2 (69%). The improvement is ascribed to the increased light absorption intensity and range as well as the reduction of electron–hole pair recombination with the introduction of CNTs

Visible light photocatalytic degradation of dyes by bismuth oxide-reduced graphene oxide composites prepared via microwave-assisted method

Bi2O3-reduced graphene oxide (RGO) composites were successfully synthesized via microwave-assisted reduction of graphite oxide in Bi2O3 precursor solution using a microwave system. Their morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) and methyl orange (MO) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, UV–vis absorption spectroscopy, and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the photocatalytic performance of Bi2O3–RGO composites. Bi2O3–RGO composite with 2 wt.% RGO achieves maximum MO and MB degradation rates of 93% and 96% at 240 min under visible light irradiation, respectively, much higher than those for the pure Bi2O3 (78% and 76%). The enhanced photocatalytic performance is ascribed to the increased light adsorption and the reduction in electron–hole pair recombination in Bi2O3 with the introduction of RGO

Sol–gel synthesis of Au/N–TiO2 composite for photocatalytic reduction of Cr(vi)

Au/N–TiO2 composites are successfully synthesized via a modified sol–gel method and their photocatalytic performance in reduction of Cr(VI) is investigated. Au/N–TiO2 composites exhibit an enhanced photocatalytic performance in the reduction of Cr(VI) with a maximum reduction rate of 90% under visible light irradiation as compared with pure TiO2 (34%) and N–TiO2 (80%) due to the increase of light absorption intensity and range as well as the reduction of electron–hole pair recombination in TiO2 with the incorporation of N and Au

Microwave-assisted synthesis of ZnO for photocatalytic reduction of Cr(VI) in aqueous solution

ZnO sheets have been synthesized via microwave-assisted reaction of ZnO precursor in aqueous solution using a CEM microwave system. Their morphologies, crystal structures and photocatalytic performances in the reduction of Cr(VI) were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy and UV-vis absorption spectrophotometer, respectively. Results show that ZnO sheets synthesized in 5 min time scale exhibits a optimal photocatalytic performance in the reduction of Cr(VI) with removal efficiency of 81% under UV irradiation due to the maximal intensity of light absorption and the minimal probability of electron-hole pair recombination.Published versio

One-step synthesis of CdS–TiO2–chemically reduced graphene oxide composites via microwave-assisted reaction for visible-light photocatalytic degradation of methyl orange

One-step synthesis of CdS–TiO2–chemically reduced graphene oxide (RGO) composites was carried out using microwave-assisted reduction of graphite oxide in CdS precursor solution with TiO2 suspension. The photocatalytic performance of CdS–TiO2–RGO composites in degradation of methyl orange was examined. Results show that the RGO addition could enhance the photocatalytic performance of CdS–TiO2 composites with maximum degradation efficiency of 99.5% under visible light irradiation as compared with the pure TiO2 (43%) and CdS–TiO2 (79.9%) composites due to the increase of specific surface area for more adsorbed MO and the reduction of electron–hole pair recombination with the introduction of RGO

Visible light photocatalytic degradation of methylene blue by SnO2 quantum dots prepared via microwave-assisted method

SnO2 quantum dots (QDs) were successfully synthesized via a microwave-assisted reaction of a SnO2 precursor in an aqueous solution using a microwave system. The morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, UV-vis absorption/reflectance spectroscopy and electrochemical impedance spectroscopy, respectively. The results show that the SnO2 QDs synthesized at a pH value of 5 exhibit an optimal photocatalytic performance with a MB degradation rate of 90% at 240 min under visible light irradiation due to their easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination

Microwave-assisted synthesis of ZnO–Y3Al5O12:Ce3+ composites with enhanced visible light photocatalysis

ZnO–Y3Al5O12:Ce3+ composites were successfully synthesized via a microwave-assisted reaction of the ZnO precursor with a Y3Al5O12:Ce3+ suspension using a microwave synthesis system. The morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, fluorescence spectrophotometer, and UV-vis absorption spectrophotometer. The results show that the introduction of Y3Al5O12:Ce3+ can enhance the photocatalytic performance of ZnO with a maximum MB degradation rate of 93% under visible light irradiation compared with pure ZnO (13%) mainly due to the light down-converting effect of Y3Al5O12:Ce3+, which facilitates the self-sensitized destruction of MB

UV-assisted photocatalytic synthesis of ZnO–reduced graphene oxide composites with enhanced photocatalytic activity in reduction of Cr(VI)

ZnO–reduced graphene oxide (RGO) composites are successfully synthesized via UV-assisted photocatalytic reduction of graphite oxide by ZnO nanoparticles in ethanol. Their morphology, structure and photocatalytic performance in reduction of Cr(VI) are characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction spectroscopy, UV–vis absorption spectrophotometer, respectively. The results show that in the composites the RGO nanosheets are decorated densely by ZnO nanoparticles, which displays a good combination between RGO and ZnO. ZnO–RGO composites exhibit an enhanced photocatalytic performance in reduction of Cr(VI) with a maximum removal rate of 96% under UV light irradiation as compared with pure ZnO (67%) due to the increased light absorption intensity and range as well as the reduction of electron–hole pair recombination in ZnO with the introduction of RGO

Efficient charge separation between UiO-66 and ZnIn2S4 flowerlike 3D microspheres for photoelectronchemical properties

It is still a great challenge to develop efficient semiconductive photocatalysts responding to visible light radiation. We show an efficient ZnIn2S4/UiO-66 hybrid photocatalysts with flowerlike 3D microspheres synthesized via a facile solvothermal method. A 20 wt.% UiO-66 emersion raises the Cr(VI) reduction rate up to 99% and higher after 60 min visible light irradiation. The substantial enhancement of photocatalytic and photoelectronchemical activity of pure ZnIn2S4 by UiO-66 addition is attributed to the ZnIn2S4/UiO-66 interfacial charge transferring and more active sites for pollute adsorption