Song Bi

Mixed photoelectrode based on spherical TiO2 nanorod aggregates for dye-sensitized solar cells with high short-circuit photocurrent density

Mixed photoelectrode was successfully prepared by dispersing spherical TiO2 nanorod aggregates with high surface area into nanocrystallites for dye-sensitized solar cells. This type of mixed photoelectrode demonstrated a considerably higher short-circuit photocurrent density value due to the multifunctions of the spherical TiO2 nanorod aggregates, including high surface area for large dye loading, sub-micrometre size for superior light-scattering ability and one-dimensional building units for fast electron transport. After maximizing the combined dye loading, light-scattering efficiency, and electron transport property in the mixed photoelectrode by adjusting the concentrations of the spherical TiO2 nanorod aggregates, a highest Jsc of 20.36 mA cm−2 and a highest energy conversion efficiency of 6.96% were obtained when the concentration of the spherical TiO2 nanorod aggregates was 40 wt%.

Molecular Dynamics Simulation of Interactions on Graphene/Polypyrrole Nanocomposites Interface

Graphene receives world-wide attention due to its unique two-dimensional structure and exceptional electrical and mechanical properties. The graphene/polypyrrole (Gr/PPy) nanocomposites, have been synthesized via dispersing the graphene into polymers, which can be widely used in microwave absorption, supercapacitors and electronic devices. Molecular dynamics simulations are carried out to investigate the microscopic mechanism of interactions on Gr/PPy nanocomposites interface. The interaction configurations, intermolecular interaction energy and pair correlation functions between graphene and PPy are computed. The curves of temperature, energy evolution and interaction energy analysis indicate that Gr/PPy system reaches equilibrium in a relatively short time, and it is a thermodynamic equilibrium system. The interaction configurations show that there is an attractive interaction between the graphene and PPy. Pair correlation functions reveal that there are van der Waals interactions and hydrogen bond between the graphene and PPy, which are strong short-range non-bonded interactions. The strong interactions mainly arise from the sp2 hybridized π-conjugated structure of graphene and PPy, which engenders π-π interaction.

Microstructure Characterization of Alumina/Carbon Nanotubes Composite Coating

Alumina/carbon nanotubes (Al2O3/CNTs) composite coating was synthesized by plasma spray employing mixtures of Al2O3-coated CNTs and nano-sized α-Al2O3 at atmosphere. This coating was characterized for the microstructure and the composition by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TG), differential scanning calorimetry analysis (DSC) and scanning electron microscopy (SEM). The results show that the thickness of the coating is about 0.5mm and the constituent elements were changed to α-Al2O3, CNTs and γ-Al2O3 duo to the superhigh temperature during the plasma spray process. The great mass of the mixtures were melted well and the CNTs were dispersed uniformly in the melted ceramic. The oxidation resistance and the microwave absorption properties were discussed simply to describe the functions of the composite coating.

Tribological Properties of Magnesium Silicate Powders Prepared by Ball Milling

Hydroxyl magnesium silicate powders were prepared by planetary-milling machine and a certain amount of No.46 mechanical oil was canned into the stainless steel vial in order to investigate its influence on the size of particles. The tribological properties of the powders in the oil were investigated on a four-ball machine. The morphologies and the chemical components of the worn surfaces were characterized by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The ball milling results showed that the adding of mechanical oil decreased the cold welding and agglomeration, finally, fine silicate powders of 2μm in mean size were made. The tribological test results showed that the extreme pressure and antiwear properties of No.46 mechanical oil were improved by the additive obviously. The lubrication mechanism is inferred that a boundary lubrication film is formed and the tribochemical reactions occur on the friction surfaces due to the active agents in the silicate crystal, thus it can be seen that the silicate powders is a new and enviroment friendly lube additive.