Synthesis Of Nano-sized Tungsten Oxide (W₁₈O₄₉) By Alcohol-Thermal Method And Its Photocatalytic Performance

Over the past few decades, the steadily worsening environmental pollution and energy shortages have raised awareness of a potential global crisis. For the sustainable development of human society, people have tried their best to find every possible solution to solve the problems. Semiconductor photocatalysis has emerged as one of the most promising technologies because the sunlight is an inexhaustible clean and renewable energy. Since the discovery of water photolysis on a TiO2 electrode by Fujishima and Honda in 1972, many semiconductors have been widely studied such as TiO2, NiO, WO3 and so on. Nano-sized W₁₈O₄₉, as its unique defected structure, has aroused much attention among researchers. In this work, we synthesized W₁₈O₄₉ nanomaterials by a facile solvothermal method and studied the photocatalytic performance of the samples. Specific content can be divided into the following three aspects:?1? The synthesis of W₁₈O₄₉ by the solvothermal method and the photocatalytic performance of the samples for the dehydration of isopropanol to propene. We prepared the W₁₈O₄₉ with isopropanol as the solvent, and briefly studied the influence of the parameters?the temperature and time of the solvothermal treatment, the dosage of WCl6? on the crystalline phase and morphology of the final products. Also, we probed into the photocataytic performance of the samples and the results suggested that the W₁₈O₄₉?180 oC, 24 h, 3.0 g WCl6? had the highest photocatalytic efficiency among the samples. Based on the results, we have the following two conclusions: I The light and the photocatalyst are two necessary conditions for the dehydration of isopropanol; II The W₁₈O₄₉ with the morphology of nanorods with tightly aggregation tends to have higher photocatalytic activity than other samples.?2? The correlation between the morphology of W₁₈O₄₉ and its photocatalytic activity for the dehydration of isopropanol to propene. We prepared nanosized W₁₈O₄₉ samples with rod-like, urchin-like and flake-like morphology in different alcohol solvents. As for the photocatalytic dehydration of the isopropanol to propene, the W₁₈O₄₉ synthesized in ethanol performed the best among the four samples.?3? The preparation of the W₁₈O₄₉/g-C₃N₄ composite photocatalysts and its photocatalytic efficiency for H2 evolution. We have successfully obtained the W₁₈O₄₉ nanowires/g-C₃N₄ nanosheets composites by a simple solvothermal process. As for the photocatalytic H2 production, the composite photocatalysts have much higher efficiency than that of pure g-C₃N₄. The optimum photocatalytic efficiency was achieved for W₁₈O₄₉?30 wt%?/g-C₃N₄ at H2 evolution rate of 3.69 ?mol h-1, which was up to 4.5 times as high as that of pure g-C₃N₄.