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首页> 外文期刊>Applied Surface Science >Enhanced photocatalytic activity of silver metallized TiO_2 particles in the degradation of an azo dye methyl orange: Characterization and activity at different pH values
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Enhanced photocatalytic activity of silver metallized TiO_2 particles in the degradation of an azo dye methyl orange: Characterization and activity at different pH values

机译：在偶氮染料甲基橙降解中，金属化的TiO_2颗粒的光催化活性增强：在不同pH值下的表征和活性

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摘要

The photocatalytic activity of silver deposited Degussa P25 titanium dioxide (Ag-DP25) in the photodegradation of methyl orange (MO) was investigated. The photocatalysts were characterized using PXRD, SEM, EDX, FTIR and UV-vis spectrophotometer. The obtained results show that the silver (Ag~0) deposited TiO_2 exhibited visible light plasmon absorption band. The degradation experiment reveals that the catalytic property of Ag-DP25 in the degradation of MO is more efficient than that of commercially available Degussa P25 TiO_2 (DP25) samples. The improvement of Ag-DP25 catalyst efficiency strongly depends on the content of silver (Ag) deposits. The present study shows that the degradation process is dominated by Ag-TiO_2 photocatalytic system, complying with pseudo-first order rate law. The higher rate of photodegradation observed on Ag-DP25 at pH 6.6 can be correlated to the ratios of the concentrations of the ionized to the neutral dye molecules and also to the higher concentration of hydroxylated surface, which are able to effectively scavenge photogenerated valence band holes. Accumulation of the holes in the semiconductor particles increases the probability of formation of excited oxygen atom which is a reactive species readily oxidizing the organic dye molecule. The reduction of pH during the course of the reaction is attributed to the complete mineralization of the dye.
机译：研究了沉积银的Degussa P25二氧化钛（Ag-DP25）在甲基橙（MO）的光降解中的光催化活性。使用PXRD，SEM，EDX，FTIR和紫外可见分光光度计对光催化剂进行了表征。所得结果表明，银（Ag〜0）沉积的TiO_2具有可见光等离子体吸收带。降解实验表明，Ag-DP25在MO降解中的催化性能比市售Degussa P25 TiO_2（DP25）样品更有效。 Ag-DP25催化剂效率的提高在很大程度上取决于银（Ag）沉积物的含量。本研究表明，降解过程以Ag-TiO_2光催化体系为主导，符合伪一级速率定律。在pH 6.6的Ag-DP25上观察到的较高的光降解速率可以与离子化的中性染料分子的浓度之比以及羟基化的表面的较高浓度有关，这可以有效地清除光生价带孔。半导体颗粒中空穴的积累增加了形成被激发的氧原子的可能性，该氧原子是易于氧化有机染料分子的反应性物质。反应过程中pH值的降低归因于染料的完全矿化。

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