Synthesis Of Quantum-Sized SnO₂and TiO₂Microspheres And Their Gas Sensing And Photovoltaic Performance

(1) Zn-doped Quantum-sized SnO2nanoparticles have been synthesized by a reverse microemulsion-assisted hydrothermal method. Pseudo-ternary phase diagram in quaternary component systems of cetyltrimethylammonium bromide (CTAB)/n-pentanol/n-hexane/water was used. The morphology and crystal structure were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray Diffraction (XRD) analyses. Surface characteristic was analysized by Fourier Transform infrared spectroscopy (FTIR) and Thermogravimetry (TG). Further, the NO2gas sensing properties of senors based on pure and Zn-doped quantum-size ZnO were measured, and Photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) were used to discuss the effect of Zn doping to the gas sensing performance.(2) Mesoporous TiO2microspheres (MSs) with rough surfzce were synthesized by direct hydrolysis of TiCl4in ethanol aqueous solution using CTAB as template. The diameter of the microspheres was about700nm, which was composed of nanocrystalline with average size of16nm. And they were used as scattering layer of CdS/CdSe quantum dot co-sensitized solar cells (QDSCs). Ultraviolet-visible and diffuse reflectance spectra showed that such micro-spherical structure was favorable for the deposition of QDs and showed a relatively higher light scattering effect, which effectively enhanced light harvesting and led to the increase of the photocurrent of the QDSCs. Electrochemical impedance spectroscopy (EIS) revealed that the electrons in QDSC with TiO2microspheres as scattering layer had the longest life time. As a result, a power conversion efficiency of4.5%has been obtained, which is higher by27.7%than that of QDSCs without scattering layers and10.2%than that of QDSCs with the traditional scattering layers composed of20nm and400nm TiO2solid particles.