Shuwang Duo

TiO2–graphene composites with exposed {001} facets produced by a one-pot solvothermal approach for high performance photocatalyst

TiO2-graphene (TOG) composites with exposed TiO2 {001} facets were prepared by a solvothermal approach without any addition of surfactants or capping agents, only using titanium isopropoxide and graphene oxide ethanol suspension as the precursors. Graphene was covered uniformly and densely with anatase TiO2 nanoparticles, exposing the {001} facets. The X-ray photoelectron spectroscopy, photoluminescence spectroscopy and photocurrent measurements show the presence of electron transfer between TiO2 and graphene. The electron transfer between TiO2 and graphene will greatly retard the recombination of photoinduced charge carriers and prolong electron lifetime, which will contribute to the enhancement of photocatalytic performance. Accordingly, the TOG composites show high photocatalytic activity of methyl orange under UV light, likely due to the effective separation of photoinduced charge, exposure of highly reactive {001} facets and great adsorptivity of dyes.

Effect of annealing processing on microstructure and properties of Ti-6Al-4V alloy by powder injection molding

Abstract Ti6A14V alloy parts were prepared by metal injection molding. Brown parts were densified at 1 200–1 260°C for 2–4 h in vacuum atmosphere. The as-sintered specimens were treated through Hot-Isostatic Pressure(HIP) at 960 °C and 140 MPa. Ti6A14V alloy compacts were annealed at 720–760 °C for 1 h. The results show that binder in the parts can be removed by solvent debinding and thermal debinding process. Ti6A14V alloy has an uniform duplex microstructure with many equiaxed α grains and a little β grains. When the annealing temperature is higher than 800 °C, Ti6A14V alloy has lower mechanical properties. After solution treatment and aging, a typical martensite microstructure can be achieved.

Au/TiO2/Graphene Composite with Enhanced Photocatalytic Activity Under Both UV and Visible Light Irradiation

Au/TiO2/graphene composite was synthesized by the combination of electrostatic attraction and photo-reduction method. In the composite, graphene sheets act as an adsorption site for dye molecules to provide a high concentration of dye near to the TiO2 and Au nanoparticles (NPs), and work as an excellent electron transporter to separate photoinduced e−/h+ pairs. Under UV irradiation, photogenerated electrons of TiO2 are transferred effectively to Au NPs and graphene sheets, respectively, retarding the recombination of electron–hole pairs. Under visible light irradiation, the Au NPs are photo-excited due to the surface plasmon resonance effect, and charge separation is accomplished by the interfacial electron injection from the Au NPs to the conduction band of TiO2 and then transfer further to graphene sheets. As a result, compared with pure TiO2, Au/TiO2/graphene composite exhibited much higher photocatalytic activity for degradation of methylene blue under both UV and visible light irradiation, based on the synergistic effect of Au, graphene in contact with TiO2, allowing response to the visible light, effective separation of photoinduced charges, and better adsorption of the dye molecules.

Synthesis of Bi 2 O 4 @TiO 2 Heterojunction with Enhanced Visible Light Photocatalytic Activity

A novel Bi2O4@TiO2 heterojunction was constructed by a simple two-step method. The charges migration between Bi2O4 and TiO2 via the heterojunction improves the electron/hole separation efficiency. Furthermore, Bi2O4@TiO2 heterostructures exhibit better adsorption capability for methyl orange molecular due to their higher specific surface area than pure Bi2O4. As a result, Bi2O4@TiO2 hybrids show an improved visible light photocatalytic activity and photostability for the degradation of methyl orange.

Stress-induced martensitic transformation in (Ni47Ti44)100-xNbx shape memory alloys with wide hysteresis

The effect of deformation via stress-induced martensitic transformation on the reverse transformation behavior of the (Ni47Ti44)(100-x)Nb-x(x=3, 9, 15, 20, 30, mole fraction, %) shape memory alloys was investigated in detail by differential scanning calorimetry (DSC) after performing cryogenic tensile tests at a temperature of M-s+30 degrees C. The results show that Nb-content has obvious effect on the process of stress-induced martensitic transformation. It is also observed that the stress-induced martensite is stabilized relative to the thermally-induced martensite (TIM) formed on cooling, and Nb-content in Ni-Ti-Nb alloy has great influence on the reverse transformation start temperature and transformation temperature hysteresis of stress-induced martensite(SIM). The mechanism of wide transformation temperature hysteresis was fully explained based on the microscopic structure and the distribution of the elastic strain energy of (Ni47Ti44)(100-x)Nb-x alloys.

Influence of different pH regulators and pH values on optical properties of ZnS nanocrystalline thin films

ZnS thin films were prepared under different pH regulators and pH values by the chemical bath deposition method (CBD). Deposition mechanism was discussed and optical properties of ZnS thin films were measured by n k d- film analysis system. Results show the addition of pH regulators is beneficial to decrease the precipitation of the solution. The decrease of the precipitation of the solution could increase the deposition rate of the film. When there is addition of NH3 and the controlled pH value is 10.9 in the solution, the deposition rate of the film is largest, which is agreement with the discussed condition that when there is no pH regulator and the pH value is dropped to 10.9 in the solution. Band edge of the transmission of all films shifts greatly to short wavelength and tends to be similar. Band gap values of all the films are larger than 4.00eV. Grain size of all the thin films is almost 5nm and the films have the pronounced quantum size effect. It shows that it is easy for ZnS to form a lot of nucleation points on the substrate, but difficult to grow up because of the existence of intermolecular hydrogen bond effect in the solution.