| With the development of the global economy and industry, more attention has been paid to the energy and environmental problems. The research of lithium-ion battery and photocatalysis has received extensive attention in order to alleviate the demand for renewable energy and reduce the environmental pollution. Metal oxides have become an important topic of research on the electrode materials of lithium-ion battery and photocatalytic materials because of their low cost, good stability and reliability, as well as facile syntheses procedure. Based on the research background, this paper reaearch content mainly includes the following several aspects:(1) WO3 and lithiated WO3 are successfully synthesized by a hydrothermal method followed by annealing at different temperatures (200-600?), and the influence of structure and composition of WO3 on the charge/discharge performance of Li-ion batteries are systematically investigated. In the AMT/LiCl/acetic acid hydrothermal systems, it was found that NH4+, NH3 and Li+ in the precursor can incorporate into the newly formed hexagonal tunnels. Residual NH4+, NH3 and Li+ in the channel are crucial for stabilizing hexagonal WO3. However, most of the NH4+ and NH3 molecule were released during the heat treatment or insertion/extraction process, meanwhile, Li+ are too small to stabilize the hexagonal structure. So the hexagonal framework collapsed in an exthermic/electrochemical reaction into monoclinic structure.Thus we consider that monoclinic structure is more stable than hexagonal structure during the insertion/extraction process. The releasing of NH3 during the insertion/extraction process caused the irreversible lithiation reaction. Therefore, the electrochemical properties strongly depend on the interaction of stabilizing neutra or cationic species. The residual NH4+, NH3 molecules has little effect on the monoclinic WO3 structure, so the monoclinic WO3 shows a better cycle life compared to hexagonal WO3. Meanwhile, the lithiation noticeably improves the specific capacity and rate capacity of WO3. We consider two effects of lithiation:On the one hand, the amount of Li+ remained in the solid structure of WO3 can reduce irreversible change of monoclinic structure during charging-discharging process and as a compensation for the loss of discharge capacity. Morever, Li+can increase the electron conductivity of WO3.(2) iodinated SnO2 QDs (particle size?2.4nm) are successfully fabricated via low temperature hydrolysis of crystalline SnI4 without any additives or templates. This route can achieve efficient mass production of SnO2 QDs with appropriate applications in many other fields such as gas sensors, lithium-ion batteries and solar cells. In the preparation of SnO2 QDs process, I species can lead to the sub-bandgap states in the QDs, Therefore, SnO2 QDs exhibit significantly enhanced visible-light-driven photocatalytic activity towards degradation of Rhodamine B and oxidation of NO in ppb level. Time-resolved fluorescence spectra confirmed that the iodine species in QDs could play a role aspassivators of the quenchers, which could diminish the surface trapping of photo-generated charges and thus enhance the lifetime of the excited states when excited above the band gap of the QDs. This effect can significantly improve the photocatalytic efficiency of the materials.(3) we investigate the charge-discharge preformance and photocatalytic performance of WO3/SnO2 composite materials. The composite material of hexagonal WO3/SnO2 QDs composite materials shows enhanced electrochemical performance, However the monoclinic WO3/SnO2 QDs composite materials reveal better photocatalytic performance, which indicated that different crystalline phase of WO3 have a great influence on the properties of the composite materials... |
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