•AgBr nanoparticles interspersed MoO3 nanobelts photocatalyst was synthesized by an oriented diffusing and charge induced deposition method.•Ultra-short photocatalytic time (5 min) and Ultra-high degradation efficiency (95%).•Noticeable photocurrent response was detected under visible light irridiation, and O2− was confirmed to be a dominant reactive specie by experiments.•Dye-sensitized-assisted electron transfer process was proposed.•Redox ability of electrons was enhanced by photon-generated carriers recombination on the ohmic contact interface.Inspired by the natural photosynthesis in green plants, artificial heterogeneous Z-scheme photocatalytic systems are widely used to settle environmental concerns and energy crises, and their excellent characteristics come from long-term stability, wide absorption range, high charge-separation efficiency, and strong redox ability. However, the contribution of the surface-adsorbed dyes antenna molecule is seldom considered in the process of Z-scheme photocatalysis. In this study, we construct AgBr quantum dots decorated MoO3 nanobelts as a novel Z-scheme photocatalyst by an oriented diffusing and charge induced deposition. For the first time, we find the synergistic effect caused by the suitable energy band match among RhB dyes, AgBr nanoparticles, and MoO3 nanobelts, leading to the ultrafast dye-sensitized-assisted electron transfer process. This is responsible for excellent photocatalytic activities of the achieved AgBr/MoO3 monolithic catalyst for degrading RhB under visible light irradiation. Simultaneously, changing of the band gaps and detailed mechanism for high efficiency degradation is analyzed and explored by theoretical calculations and designing further experiments. It is proposed that ultrafast degradation of the RhB on the AgBr/MoO3 nanocomposites is due to both the photocatalytic process and the dye sensitization; the superoxide radical O2−, which is produced by accumulated dye-sensitization-induced abundant electrons with powerful potential in the CB of AgBr accompanying by quick combination of electrons in the CB of MoO3 with photogenerated holes in the VB of AgBr, is a dominant reactive species for the degradation of RhB under visible light irradiation.Download high-res image (186KB)Download full-size image

•Using a facile hydrothermal method, Cu2S thin films were in-situ grown on Cu foil.•Crystallization and surface roughness depended on surfactants and reaction temperature.•Degradation rate of methylene blue was affected by Cu2S thin films.•Good catalytic performance was attributed to hetero-junction formed between Cu and Cu2S.Cu2S thin films were successfully grown in situ on Cu foil by an easy hydrothermal method. The effects of surfactant and reaction time on the formation of the Cu2S films were studied by X-ray diffraction, field-emission scanning electron microscopy and ABIOS profilometry. Results showed that the thin films consisted of nanoparticles, and their crystallization and surface roughness depended on the structures of surfactants and reaction time. Photocatalytic studies indicated that the film obtained at 1 h by the EDTA-2Na surfactant exhibited a good methylene blue degradation rate of 83.7%, and higher values of 89.2% and 90% were obtained with increased reaction time to 3 and 4 h. Even the decomposition rate remained at high (82%) after reuse. This good catalytic performance can be attributed to the heterojunction formed between Cu and Cu2S, the special surface from the reaction between [Cu-EDTA]- ion and S2−, and the further crystal orientation with prolonged reaction time.

Effect of minor Gd addition on the microstructure, mechanical properties and wear behavior of as-cast Mg–5Sn-based alloy was investigated by means of OM, XRD, SEM, EDS, a super depth-of-field 3D system, standard high-temperature tensile testing and dry sliding wear testing. Minor Gd addition has strong effect on changing the morphology of the Mg–5Sn binary alloy. Gd addition benefits the grain refinement of the primary α-Mg phase, as well as the formation and homogeneous distribution of the secondary Mg2Sn phase. The mechanical properties of the Mg–5Sn alloys at ambient and elevated temperatures are significantly enhanced by Gd addition. The wear behavior of the Mg–5Sn alloy is also improved with minor Gd addition. The alloy with 0.8% Gd addition exhibits the best ultimate tensile strength and elongation as well as the optimal wear behavior. Additionally, the worn surface of the Mg–5Sn–Gd becomes smoother in higher Gd-containing alloys. The best wear behavior of alloy was exhibited when Gd addition was up to 0.8%, showing a much smoother worn surface than that of control sample. The improvement of tensile properties is mainly attributed to the refinement of microstructure and the increasing amount and uniform distribution of Mg2Sn phase. The larger amount of Mg2Sn phase uniformly distributed at the grain boundary of Mg–Sn–Gd alloys act as a lubrication during sliding, and combined with smaller grain size improve wear behavior of the binary alloy.

•Using a low-temperature solid-state method, ZnO/CdS nanocomposites were obtained•Grain growth kinetics of cubic CdS and hexagonal ZnO phase was described.•Sufficient grinding and heating treatment was a key for formation of composites.•Optical properties could be easily manipulated by reaction temperature and time.A simple low-temperature solid-state reaction in the presence of the surfactant PEG400 was developed to obtain ZnO/CdS nanocomposites. The effects of synthesis temperature and reaction time on crystal structure and optical properties of the nanocomposites were investigated by several technologies. X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) characterizations showed that the products consisted of the nanoparticles, and the grain growth kinetics of the cubic CdS and the hexagonal ZnO phase in the nanocomposites was described. The mechanism analysis suggested that sufficient grinding and heating treatment was a key to form the ZnO/CdS nanocomposites, and the surfactant PEG400 was proved not to involve the reaction and prevent the nanoparticles from aggregating to larger in whole grinding and heat-treatment process. Ultraviolet–visible (UV–vis) spectra revealed that the band gaps of the nanocomposites could be tuned by the reaction temperature and reaction time. Photoluminescence (PL) spectra showed that the changing position and the intensity of the emission peaks resulted from the rate of electron transfer and recombination probability under the different conditions.

•Flower-like MoS2 spheres were successfully prepared via a facile hydrothermal method.•The highest visible degradation rate of 95.61% was obtained at an S/Mo ratio of 2.75.•Enhanced photocatalytic activity came from large exposing areas of the {100} surface.Flower-like MoS2 spheres were successfully prepared via a facile hydrothermal method. The effects of excess sulfur on the formation of MoS2 were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD pattern showed that the preferential orientation of the flower-like hexagonal 2H–MoS2 spheres was the (002) plane, and I002/I100 ratio values indicated that the (002) plane grew more completely than the (100) plane with increasing S/Mo ratio. The FESEM images revealed that the sheet thickness of the MoS2 spheres increased to ~30 nm with increasing S/Mo ratio, exposing more edges on the nanosheets of the MoS2 spheres. Photocatalytic properties of the products were studied, and the results showed that the MoS2 sample with a S/Mo ratio of 2.75 exhibited the highest degradation rate constant and methylene blue degradation rate under 90 min visible light irradiation. The results showed that the enhancement of photocatalytic activity originated from increasing exposed area of the {100} facets with increasing S/Mo ratio under the hydrothermal environment.

A simple low-temperature solid-state synthetic method was employed to obtain ZnS–CdS and CdS–ZnS alloy nanoparticles. The effects of reaction sequence, reactant molar ratios, and synthesis temperature on the products were investigated. The crystal structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared (FT-IR) spectroscopy. The results show that the products are alloy nanoparticles with a cubic phase structure. The formation mechanism of the alloy nanoparticles is briefly discussed. Sufficient grinding and crystalline water may be essential to form alloy nanoparticles. Ultraviolet–visible (UV–vis) spectra show that the edge absorptions of the CdS–ZnS and ZnS–CdS nanoparticles were located between those of ZnS and CdS bulks, and the absorbance at the peak maximum was practically dependent on reaction temperature, reaction sequence, and molar ratio. Extrinsic deep-level emission resulted in strong peaks in the photoluminescence (PL) spectra. The position and intensity of the emission peaks varied with the conditions during synthesis.Highlights► Using a simple low-temperature solid-state synthetic method, ZnS–CdS and CdS–ZnS alloy nanoparticles were obtained, respectively. ► The size of the nanoparticles increased with increasing reaction temperature, and reaction sequence had no effect on the size of the nanoparticles under the same temperature. ► The particle diameters of the CdS–ZnS products decreased gradually with increasing Cd2+/Zn2+ molar ratio, whereas those of the ZnS–CdS products increased gradually with increasing Zn2+/Cd2+ molar ratio. ► The study shows that sufficient grinding and crystalline water may be a key in forming the alloy nanoparticles. ► Optical properties of the products depend on reaction temperature, reactant addition sequence, and reactant molar ratio.