三氧化钨/氧化银复合材料的水热法合成及其光催化降解性能研究

Dye pollution, one of the most serious problems in water pollution, has attracted the attention of scientists. There are many methods, such as chemical oxidation, physical adsorption, biodegradation, photocatalysis, etc., that have been adopted to handle the crisis of dye polultion. Compared with other strategies, photocatalysis has its unique advantages including low energy consumption, environment amicableness and high efficiency. Tungsten trioxide (WO₃), a semiconductor with a band gap of 2.8 eV, has unique physical and chemical properties, and it has been applied to the area of photocatalysis to solve the problem of water pollution in recent years. However, the photocatalytic efficiency of bulk tungsten oxide fails to reach the expected. In this paper, a one-dimensional complex of tungstun trioxide and silver oxide (WO₃/Ag₂O) is synthesized via a simple hydrothermal method for photocatalytic degradation of methylene blue. The crystal structure, morphology and photocatalytic degradation ability towards methylene blue are characterized and analyzed via X-ray diffraction, scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, and UV-Vis spectrophotometer. Silver oxide (Ag₂O), with a band gap of 1.2 eV, is found to be sensitive to visible light. The combination of tungsten trioxide and silver oxide promotes its photocatalytic efficiency dramatically under visible light illumination. Results show that WO₃ nanorods in the composite possess a one-dimensional, hexagonal structure with an average length of 4 _m and a diameter of 200 nm. The Ag₂O attached to WO₃ nanorods forms hexagonal nanoparticles and their average diameter reaches 20 nm. It is observed that WO₃/Ag₂O composite displays a loose structure and a high specific surface area, which provides more reactive sites. Comparing with single component, UV-Vis spectrophotometry shows that the composite has a highabsorbance in the range of visible light. The combination of tungsten trioxide and silver oxide can change the band gap of the photocatalyst whereas the photocatalytic efficiency of the composite reaches 98% in 60 min under visible light. Therefore, the synergistic effect of WO₃ and Ag₂O plays a vital role in enhancing the photocatalytic performance. Moreover, the stability of photocatalyst is one of the most important indicators of its recycling and long-term effectiveness, and the present WO₃/Ag₂O composite has good catalytic and chemical stability. This investigation proves that the combination of wide bandgap photocatalysts with visible-light sensitive metal oxide with large specific area will improve photocatalytic activity efficiently under visible light.