Zhang Xingtang

Solvothermal synthesis of CdS nanorods and photovoltaic characteristics of CdS/PVK composite system

Large quantities of CdS nanorods are successfully synthesized through Cd(CH3COO)2·2H2O reacting with Na2S·9H2O and EDA in aqueous solution. XRD result shows that the sample is of hexagonal structure. And TEM result shows that the morphologies of the resulting CdS are mainly in three-armed rod-like structure with a diameter of 10–15 nm and a length of 100 nm. The nanocomposites of CdS/PVK with different molar ratios are prepared by spin coating method on tin-doped indium oxide (ITO) substrate. A notable decrease of photoluminescence (PL) efficiency and a significant enhancement of surface photovoltage signal have been observed in CdS/PVK composites when the molar fraction of CdS increases. We interpret these results as the energy level matching between CdS and PVK in nanocomposites. This energy level matching facilitates fast interfacial charge transfer then increases the separation efficiency of electron-hole pairs and the carrier generation efficiency. The detailed charge transfer process has also been demonstrated.

Investigation of tribological properties of composite C60-LB films

Composite C60-LB films were fabricated by the Langmuir-Blodgett (LB) technique, their micro-structures, micro-and macro-tribological properties were investigated using atomic force microscope/friction force microscope (AFM/FFM). The results showed that in the confined C60-LB films there were two kinds of structures for the special C60 assembly: grain diameters of one kind were in the range of 150–230 nm; the other was smaller than 20 nm. Micro-tribological studies showed that topographical images of tiny C60 aggregates (<20 nm) were consistent with their frictional ones very well, namely, low friction occurred on tiny C60 aggregates compared with fatty chains LB monolayer, and ‘Micro-rolling effect’ was apparent; but for big large ones frictional forces were relatively high and ‘ratchet mechanism’ was seen apparently. Macro-tribological data proved large C60 aggregates had wear resistance and load-carrying capacities and anti-wear lives for composite C60-LB films were prolonged greatly with dispersibility of C60 improved and its grain diameter reduced. Tiny C60 aggregates were mainly the lubricating agents. Friction coefficients of composite C60-LB films gradually reduced with loads increasing having the same friction coefficient-load relations with boundary lubrication films.

Synthesis of highly ordered SnO2/Fe2O3 composite nanowire arrays by electrophoretic deposition method

Highly ordered SnO2/Fe2O3 composite nanowire arrays have been synthesized by electrophoretic deposition method. The morphology and chemical composition of SnO2/Fe2O3 composite nanowire arrays are characterized by SEM, TEM, EDX, XPS, and XRD. The results show that the SnO2/Fe2O3 composite nanowires are about 180 nm in width and tens of microns in length, and they are composed of small nanoparticles of tetragonal SnO2 and rhombohedral a-Fe2O3 with diameters of 10–15 nm. The SnO2/Fe2O3 composite nanowires are formed by a series of chemical reactions.