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Photocatalytic Degradation of Methylene Blue over TiO2 Pretreated with Varying Concentrations of NaOH
摘要： In this paper, different NaOH concentrations (2, 5, 10, and 15 M) were used to treat {001}TiO2. The effect of NaOH on the crystal structure, morphology, optical properties, light raw electronic-hole recombination, and degradation performance of {001}TiO2 on methylene blue were studied. The results demonstrate that rutile TiO2 appeared when the NaOH concentration was as high as 10 M, showing much better photolytic performance than others. As the concentration of sodium hydroxide increases, the morphology changes accordingly. The specific surface area increases and the optical electronic-hole recombination rate decreases. Radical scavenging tests showed that hydroxyl radical and hole are very important in photocatalysis.
关键词： NaOH concentration,radical scavenging,{001}TiO2,methylene blue,photocatalysis
更新于2025-11-14 17:03:37
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Photocatalytic oxidation of nitrogen oxides over {001}TiO2: the influence of F? ions
摘要： A series of anatase TiO2 nanosheets with different percentage of {001} facets ({001}TiO2) were synthesized through a hydrothermal route using tetrabutyltitanate as a titanium precursor and HF as a shape controlling agent. The amount of HF exhibits an obvious influence on the structures and activities of TiO2 samples. The adsorbed surface F? ions on the {001} facets of the anatase TiO2 were removed by washing them with NaOH solution. The as-prepared catalysts were characterized by X-ray diffraction, Brunner?Emmet?Teller measurements, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy techniques, and X-ray photoelectron spectroscopy analysis. The results indicated that all the as-prepared catalysts showed an anatase crystalline and nanosheet structure, as well as a strong ultraviolet light absorbance. With the increase of HF content, the crystallite size and the percentage of {001} facets increased first and later decreased, state the opposite change observed in BET. When the content of HF was 4.4 mL, the percentage of {001} facets reached the maximum up to 61.62%. After all samples were treated with 0.1 M NaOH solution, the percentage of {001} facets increased to a maximum of 64.46%. All the samples washed by NaOH solution exhibited much higher photocatalytic activity for NOx oxidation under UV light irradiation than P25, {101}TiO2, and {001}TiO2 without NaOH washing, suggesting that the surface F? ions inhibited the photocatalytic NOx oxidation. Moreover, the results showed that the NaOH-washed {001}TiO2 has a high humidity tolerance.
关键词： Surface F? ions,{001}TiO2,Photocatalysis,NOx oxidation
更新于2025-09-19 17:15:36