Degradation Efficiency Of RhB Research Articles

Variant effect of graphene sheets and ribbons on photocatalytic activity of TiO2 sheets/graphene composite

To investigate the effect of graphene sheets and ribbons on photocatalysis, the composite of anatase TiO2 nanosheets (TiO2-NS) and graphene materials was prepared. Graphene oxide sheet (GOS) was synthesized by a modified Hummers’ method, and graphene oxide ribbon (GOR) was formed by unzipping carbon nanotubes. UV–vis absorption spectrum and X-ray photoelectron spectroscopy (XPS) reveal that GOSs and GORs were photoreduced with TiO2-NS under ultraviolet irradiation. The as-prepared TiO2 nanosheets/graphene sheets (TS-GNSs) or ribbons (TS-GNRs) display drastically quenching of photoluminescence (PL) intensity and lower electron impedance, and TS-GNSs show better results than TS-GNRs. It is due to the excellent mobility of charge carriers and large surface area with graphene, which facilitate the separation of electron–hole pairs. Thus, TS-GNSs and TS-GNRs exhibit prominent photocatalytic activity under ultraviolet irradiation. The degradation efficiency of RhB is nearly 80% for TS-GNRs and 100% for TS-GNSs within 25min. The lower degradation efficiency of TS-GNRs is due to the lower charge mobility of GNRs, which demonstrates that the excellent charge mobility of graphene plays a crucial role in composites for photodegradation.

Photocatalytic activity of hexagonal prism Sm(OH)3 nanocrystallites for decomposition of Rhodamine B

Morphology-controlled samarium hydroxide (Sm(OH)3) nanocrystallites were prepared by a facile hydrothermal process. The phase composition, morphologies and optical properties of the samples were characterized by X-ray diffraction, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. Results show that the as-prepared Sm(OH)3 nanocrystallites are hexagonal phase with prism-like microstructures in different sizes with reaction temperatures of 140°C and 180°C. These hexagonal prisms exhibit morphology-related ultraviolet absorbing ability with different optical band gaps from 3.89eV to 3.97eV. Furthermore, the above samples are found to be able to degrade RhB during photocatalytic reaction process, in which the sample sizes are believed to greatly affect the final degradation efficiency of RhB in the test.

A facile mixed-solvothermal route to γ-Bi2MoO6 nanoflakes and their visible-light-responsive photocatalytic activity

γ-Bi2MoO6 nanoflakes were successfully synthesized by a mixed-solvothermal process with SDBS involved in the reaction. The as-prepared γ-Bi2MoO6 was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis absorption spectroscopy. The effect of different ratio of solvents on the resulting products was investigated. The visible-light-responsive photocatalytic activities of the obtained γ-Bi2MoO6 nanoflakes were evaluated by photodegradation of Rhodamie B under visible light (λ>400nm). The high degradation efficiency of RhB was attributed to the good crystallization and flake-like morphology of γ-Bi2MoO6 nanostructures, which is in accord with the photocurrent result.

Preparation of various kinds of copper sulfides in a facile way and the enhanced catalytic activity by visible light

Various kinds of copper sulfides (CuS, a mixture of Cu7S4–CuS and Cu9S5) were synthesized by simply adjusting the amount of copper chloride and sodium sulfide in a solvothermal process. The different molar ratios of copper chloride and sodium sulfide result in the formation of different kinds of copper sulfides with various morphologies, such as tiny particle, hexagonal plate and octahedron. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. And the optical properties of the products were recorded by means of UV-Vis absorption and photoluminescence spectroscopy. Moreover, due to the presence of visible light, we found that the catalytic activities of the products for oxidation and decomposition of Rhodamine B with the assistance of hydrogen peroxide were enhanced, and the degradation efficiency of RhB was increased from 40% to 98% in 15 minutes at room temperature.