Cai Weimin

Review of surface photovoltage spectra of nano- sized semiconductor and its applications in heterogeneous photocatalysis

Abstract Heterogeneous photocatalysis is a promising technique valuable for environmental purification. Nano-sized semiconductors such as ZnO and TiO 2 , which is one of the most basic functional materials, have emerged as effective photocatalyst materials. The surface photovoltage spectra (SPS) can be an effective method for quickly evaluating the photocatalytic activity of semiconductor materials since it can provide a rapid, non-destructive monitor of the semiconductor surface properties such as surface band bending, surface and bulk carrier recombination and surface states, mainly showing the carrier separation and transfer behavior with the aid of light, especially the electric-field-induced surface photovoltage spectra (EFISPS), in which SPS is combined with the electric-field-modified technique. In this review, the basic principles, measurement and applications of the SPS and EFISPS are mainly discussed together with some fundamental aspects like the electric properties of semiconductor surface and the principle of electric field effect. In particular, the applications of SPS to nano-sized semiconductors such as ZnO and TiO 2 in heterogeneous photocatalysis are emphasized, which involve mainly evaluating the photocatalytic activity by analyzing semiconductor surface properties such as the separation efficiency of photoinduced carriers under illumination by the SPS measurement, highlighting our own contributions. The results show that the weaker the surface photovoltage signal is, the higher the photocatalytic activity is in the case of nano-sized semiconductor photocatalysts.

synthesis and application studies of castor oil PU/PMMA IPNs with BaTiO3 fiber nanocomposites

Abstract A series of castor oil polyurethane/poly(methyl methacrylate) interpenetrating polymer networks (IPNs) curing at room temperature are synthesized by simultaneous method and also gradient coating materials. Component analysis and viewing results of morphology and miscibility among the multi-phases of materials obtained by TEM indicate that the systems belong to graft-mode IPNs and domains between two phases are controlled in the range of nanometer scale. Furthermore, the systems are composted with selected BaTiO3 fibers, and the composite techniques are determined. Also, the thermoelectric and mechanical properties are discussed in details