Fabrication of Au/graphene-wrapped ZnO-nanoparticle-assembled hollow spheres with effective photoinduced charge transfer for photocatalysis.

Heterostructures of gold-nanoparticle-decorated reduced-graphene-oxide (rGO)-wrapped ZnO hollow spheres (Au/rGO/ZnO) are synthesized using tetra-n-butylammonium bromide as a mediating agent. The structure of amorphous ZnO hollow spheres is found to be transformed from nanosheet- to nanoparticle-assembled hollow spheres (nPAHS) upon annealing at 500 °C. The ZnO nPAHS hybrids with Au/rGO are characterized using various techniques, including photoluminescence, steady-state absorbance, time-resolved photoluminescence, and photocatalysis. The charge-transfer time of ZnO nPAHS is found to be 87 ps, which is much shorter than that of a nanorod (128 ps), nanoparticle (150 ps), and nanowall (990 ps) due to its unique structure. The Au/rGO/ZnO hybrid shows a higher charge-transfer efficiency of 68.0% in comparison with rGO/ZnO (40.3%) and previously reported ZnO hybrids. The photocatalytic activities of the samples are evaluated by photodegrading methylene blue under black-light irradiation. The Au/rGO/ZnO exhibits excellent photocatalytic efficiency due to reduced electron-hole recombination, fast electron-transfer rate, and high charge-transfer efficiency.

Photoluminescence Properties and Photocatalytic Performance of Different Size ZnO Nanoparticles Decorated Graphene Oxide.

We synthesized the hybrid structure of the graphene oxide (GO) sheet and the size-controlled ZnO nanoparticles. The ZnO quantum sizes were confirmed from UV-vis spectrophotometry and TEM results. The ZnO quantum dot exhibited a stable broad and strong photoluminescence (PL) emission which is broader with the increase of ZnO nanoparticle size. The hybrid ZnO/GO results an abrupt decrease of PL emission and the excellent photodegradation performance of methylene blue under UV-light irradiation. A considerable increase of the photodegradation rate with decreasing ZnO nanoparticle size is due to the enhancement of ZnO surface interaction and the improvement of electron transfer at the ZnO/GO interface.

Photocatalytic activity of metal-inserted WO3 thin films prepared by RF magnetron sputtering.

Metal (Au,Pt)-inserted WO3 thin films were deposited on quartz glass using a radio frequency magnetron sputtering method. Their structural and optical properties were analyzed by scanning electron microscopy, X-ray diffractometry, absorption spectrometry, and photoluminescence spectrometry. The photocatalytic activities of the films were investigated by the measurement of photodecomposition of methylene blue under visible-ray irradiation. Metal-inserted WO3 films showed higher photocatalytic activity than WO3 film. Pt-inserted WO3 thin film showed the most effective decomposition efficiency, it is due to the high absorption and the suppression of recombination between photo-excited electrons and holes.

Visible light photocatalytic activity of N-ion implanted TiO2 thin films prepared by oblique incident electron-beam evaporation method.

TiO2 thin films were prepared using electron-beam evaporation method with various oblique angles of 0 degrees, 30 degrees, 60 degrees and 75 degrees. All samples were annealed at 600 degrees C for 1 hour in air and their visible light photocatalytic properties were characterized after nitrogen implantation. The photocatalytic activity of the thin films was evaluated by the photodecomposition of methylene blue. The photocatalytic activity of N-ion implanted TiO2 film deposited with the oblique angle of 60 degrees was considerably enhanced due to high visible light absorption and low charge carrier recombination by sufficient N-ion implantation.

Synthesis of hierarchical rose bridal bouquet- and humming-top-like TiO2 nanostructures and their shape-dependent degradation efficiency of dye.

Novel hierarchical rose bridal bouquet- and humming-top-like nanostructured TiO(2) were successfully prepared by the simple process with the hydrothermal temperature as the morphology-controlling factor. The gradual transformation from layered titanate to brookite phase was well consistent with the formation mechanism of the hierarchical morphologies. The three-dimensional flower bouquets built from the bunches of roses with surrounding fern fronds displayed the best adsorptivity and completely degraded methylene blue within 60 min under UV irradiation, whereas the humming-top geometry composed of anisotropically elongated spindle-like crystallites was detrimental to the dye photodegradation.