Photocatalytic reduction of Cr(VI) on WO3 doped long TiO2 nanotube arrays in the presence of citric acid
Photocatalytic reduction of Cr(VI) on WO3 doped long TiO2 nanotube arrays in the presence of citric acid
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DOI：
10.1016/j.apcatb.2009.11.002
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发表时间：
2010-02
影响因子：
22.1
通讯作者：
Lixia Yang;Yan Xiao;Shaohua Liu;Yue-Fang Li;Q. Cai;S. Luo;G. Zeng
中科院分区：
文献类型：
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作者：
Lixia Yang;Yan Xiao;Shaohua Liu;Yue-Fang Li;Q. Cai;S. Luo;G. Zeng
在柠檬酸存在下，成功地实现了Cr（VI）在WO 3掺杂的TiO 2纳米管（NT）阵列上的光还原。通过对负载过氧钨酸的阳极二氧化钛纳米管进行退火处理，制备了WO 3掺杂的TiO 2纳米管阵列。在静电力的驱动下，带负电的过氧钨酸溶胶均匀地附着在带正电的二氧化钛纳米管阵列上，退火后形成WO 3和TiO 2的固溶体。柠檬酸在Cr（VI）的光还原反应中起着重要的作用：（i）柠檬酸作为牺牲电子给体消耗激发态TiO 2中的光生空穴;（ii）柠檬酸由于其富电子的性质，在紫外光照射下参与了Cr（VI）的氧化还原反应。在模拟太阳光下，柠檬酸中Cr（VI）的光化学还原速率为6.9μg/Lmincm ~ 2。扣除上述部分，光催化剂光生电子对Cr（VI）的还原速率从TiO_2 NTs的8.3μg/Lmincm ~ 2提高到含1at%W的WO_3/TiO_2 NTs的31.6μg/Lmincm ~ 2。WO 3/TiO 2 NT阵列上Cr（VI）的净还原率是未改性TiO 2 NT上的3.76倍。由于WO 3和TiO 2都能被紫外光激发，因此WO 3/TiO 2的光催化活性增强是由于WO 3的掺杂（带隙为2.6eV）增加了载流子分离的可能性和在可见光区的光响应光谱。
Photoreduction of Cr(VI) was successfully achieved on WO3doped TiO2nanotube (NT) arrays in the presence of citric acid. WO3doped TiO2NT arrays were fabricated by annealing anodic titania NTs that were preloaded with peroxotungstic acid. Driven by electrostatic force, the negatively charged peroxotungstic acid sol uniformly clung to the positively charged titania NT arrays, causing a solid solution of WO3and TiO2after annealing. The citric acid plays an important role in the photoreduction of Cr(VI): (i) it works as a sacrificial electron donor to deplete the photogenerated holes from the excited TiO2; and (ii) it takes part in the redox with Cr(VI) under UV illumination because of its electron rich property. The photochemical-reduction rate of Cr(VI) in citric acid under simulated solar light was 6.9μg/Lmincm2. Subtracting the part mentioned above, the reduction rate of Cr(VI) due to photogenerated electrons from excited photocatalysts increased from 8.3μg/Lmincm2on TiO2NTs to 31.6μg/Lmincm2on WO3/TiO2NTs containing 1at% of W. The net Cr(VI) reduction rate on WO3/TiO2NT arrays is 3.76 times that on the unmodified TiO2NTs. Since both WO3and TiO2can be excited by UV light, the enhanced photoactivity of WO3/TiO2is attributed to the increased probability of charge–carrier separation and the extended photo-response spectrum in visible light region due to the doping of WO3(band gap: 2.6eV).