Yunhui He

Sn3O4: a novel heterovalent-tin photocatalyst with hierarchical 3D nanostructures under visible light

Sn3O4 with hierarchical 3D nanostructures was synthesized for the first time by a facile template-free solvothermal method. The heterovalent photocatalyst is highly efficient and stable in the degradation of azo dyes under visible light.

Rapid microwave hydrothermal synthesis of GaOOH nanorods with photocatalytic activity toward aromatic compounds

GaOOH nanorods were synthesized from Ga(NO(3))(3) via a facile microwave hydrothermal method. The obtained sample was characterized by x-ray diffraction, N(2) sorption-desorption, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, electron spin resonance, and x-ray photoelectron spectroscopy. The results revealed that the as-synthesized sample was consisted of rod-like particles. It possessed a surface area of 14.3 m(2) g(-1), and a band gap of 4.75 eV. The photocatalytic property of GaOOH nanorods was evaluated by the degradation of aromatic compounds (such as benzene and toluene) in an O(2) gas stream under ultraviolet (UV) light illumination. The results demonstrated that GaOOH nanorods exhibited superior photocatalytic activity and stability as compared to commercial TiO(2) (P25, Degussa Co.) in both benzene and toluene degradation. In the extended (35 h) reaction test toward benzene, GaOOH maintained a high activity, and no obvious deactivation was observed. A possible mechanism of the photocatalysis over GaOOH is proposed.

On the role of low-energy electrons in the radiosensitization of DNA by gold nanoparticles

Four different gold nanoparticle (GNP) preparations, including naked GNPs and GNPs coated either with thiolated undecane (S-C(11)H(23)), or with dithiolated diethylenetriaminepentaacetic (DTDTPA) or gadolinium (Gd) DTDTPA chelating agents, were synthesized. The average diameters, for each type of nanoparticle, are 5 nm, 10 and 13 nm, respectively. Dry films of plasmid DNA pGEM-3Zf(-), DNA with bound GNPs and DNA with coated GNPs were bombarded with 60 keV electrons. The yields of single and double strand breaks were measured as a function of exposure by electrophoresis. The binding of just one GNP without coating to DNA containing 3197 base pairs increases single and double strand breaks by a factor of 2.3 while for GNPs coated with S-C(11)H(23) this factor is reduced to 1.6. The GNPs coated with DTDTPA and DTDTPA:Gd in the same ratio with the DNA, produce essentially no increment in damage. These results could be explained by the attenuation by the coatings of the intensity of the low-energy photoelectrons emitted from the GNPs. Thus, coatings of GNPs may considerably attenuate the short-range low-energy electrons emitted from gold, leading to a considerable decrease of radiosensitization. According to our results, the highest radiosensitization should be obtained with GNPs having the shortest possible ligand, directed to the DNA of cancer cells.

Fabrication of a novel Z-scheme g-C3N4/Bi4O7 heterojunction photocatalyst with enhanced visible light-driven activity toward organic pollutants

In this work, highly efficient g-C3N4/Bi4O7 heterojunction photocatalysts have been successfully fabricated by a facile method. Compared with the bare photocatalysts, the obtained g-C3N4/Bi4O7 hybrid photocatalysts exhibited efficient degradation activity toward methylene blue (MB), phenol, rhodamine B (RhB), and bisphenol A (BPA) under visible light irradiation. The influences of different g-C3N4 contents on the photocatalytic efficiency of the hybrid photocatalysts have been investigated. The results revealed that the g-C3N4/Bi4O7 with g-C3N4 mass ratio of 30% exhibited the best photocatalytic activity. The activity enhancement should be ascribed to the improved visible light adsorption as well as the effective Z-scheme charge transfer according to the energy band theory. The UV-vis diffuse reflectance spectra (DRS) shows that the absorption edge of g-C3N4 move towards longer wavelength with the increment of Bi4O7 component. The strong connection between g-C3N4 and Bi4O7 was investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Subsequently, the effective Z-scheme charge transfer has also been verified by using transient photocurrent measurements and electrochemical impedance spectroscopy. Controlled experiments proved that active species of O2- and h+ were produced in the degradation system, which played the major role in the degradation of MB. A possible Z-scheme degradation mechanism over g-C3N4/Bi4O7 hybrid photocatalysts was proposed.

Rod-like Bi4O7 decorated Bi2O2CO3 plates: Facile synthesis, promoted charge separation, and highly efficient photocatalytic degradation of organic contaminants

In this manuscript, rod-like Bi4O7 decorated Bi2O2CO3 plates were fabricated for the first time. Compared with pristine Bi2O2CO3, the tight decoration of Bi4O7 over Bi2O2CO3 plates not only strengthened the visible light absorption, but also enhanced the separation efficiency of photo-generated carriers. As expected, the heterostructured Bi4O7/Bi2O2CO3 composites have exhibited highly promoted photocatalytic activities in decomposing Rhodamine B (RhB) under visible light. The BOBC-2 sample displayed the best activity with a reaction rate constant of 0.0245 min-1, which was 3.8 times higher than that of pure Bi4O7. Besides RhB, the Bi4O7/Bi2O2CO3 composites also displayed superior activity toward colorless contaminants with stable chemical structures, such as phenol, p-tert-butylphenol, and o-phenylphenol. The activity enhancement should be ascribed to the proper energy levels of the materials and formation of heterojunction at their interfaces, which could facilitate the charge transfer and promote the separation efficiency. Following transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence emission tests all verified this. In addition, controlled experiments using various radical scavengers proved that O2- and h+ played the chief role in decomposing organic pollutants. This work may provide a new method for constructing Bi-based heterostructured photocatalysts with high activity.