Noble metal/semiconductor nanocomposites play an important role in high efficient photocatalysis. Herein, we demonstrate a facile strategy for fabrication of hollow Pt-ZnO nanocomposite microspheres with hierarchical structure under mild solvothermal conditions using Zn (CH(3)COO)(2)·2H(2)O and HPtCl(4) as the precursors, and polyethylene glycol-6000 (PEG-6000) and ethylene glycol as the reducing agent and solvent, respectively. The as-synthesized ZnO and Pt-ZnO composite nanocrystals were well characterized by powder X-ray diffraction (XRD), nitrogen-physical adsorption, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), and photoluminescence (PL) emission spectroscopy. It was found that Pt content greatly influences the morphology of Pt-ZnO composite nanocrystals. Suitable concentration of HPtCl(4) in the reaction solution system can produce well hierarchically hollow Pt-ZnO nanocomposite microspheres, which are composed of an assembly of fine Pt-ZnO nanocrystals. Photocatalytic tests of the Pt-ZnO microspheres for the degradation of the dye acid orange II revealed extremely high photocatalytic activity and stability compared with those of pure ZnO and corresponding Pt deposited ZnO. The remarkable photocatalytic performance of hollow Pt-ZnO microspheres mainly originated from their unique nanostructures and the low recombination rate of the e(-)/h(+) pairs by the platinum nanoparticles embedded in ZnO nanocrystals.

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Trace Ag 2 CO 3 (0.5%, 1%, 2%, and 4%) was loaded on commercial TiO 2 crystals by a facile precipitation method. The obtained Ag 2 CO 3 /TiO 2 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), photolimunescence (PL) spectroscopy, and UV−vis diffuse reflectance spectroscopy (DRS). Under UV light (λ = 254 nm) or visible light irradiation, the photocatalytic performance of the samples was tested in degradation of methyl orange (MO). Results showed that loading of 1 wt % Ag 2 CO 3 results in the best photocatalytic activity. Under UV or visible light irradiation, the degradation activity of 1%Ag 2 CO 3 /TiO 2 composite is 6 times that of TiO 2 and 4 times that of Ag 2 CO 3 or 3.4 times that of TiO 2 and 1.7 times that of Ag 2 CO 3 . Reasons for enhanced activity were found that the coupling of Ag 2 CO 3 promoted the visible light absorption and suppressed the recombination rate of e − /h + pairs. Moreover, more surface OH groups over the Ag 2 CO 3 /TiO 2 composite can react with the photogenerated h + and produce • OH radicals to decompose the dye.

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