School of Material Science and Nanotechnology, Jadavpur University, Kolkata 700 032, India.
ACS Appl Mater Interfaces. 2013 Jan 23;5(2):331-7. doi: 10.1021/am302136y. Epub 2012 Dec 31.
Type-II p-n junction three-dimensional Ag(2)O/TiO(2) microspheres have been fabricated by assembling p-type Ag(2)O nanoparticle on n-type TiO(2) 3D microsphere. Ag(2)O/TiO(2) microsphere nanoheterojunctions were obtained by hydrothermal synthesis of TiO(2) microspheres at 180 °C followed by photoreduction of AgNO(3). The samples were carefully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The photocatalytic activity toward degradation of methyl orange (MO) aqueous solution under UV light was investigated. The result showed that type-II p-n nanoheterojunctions Ag(2)O/TiO(2) significantly enhanced the photocatalytic degradation compared to n-type TiO(2) microsphere. It was found that the photocatalytic degradation followed the pseudo first-order reaction model. In particular, heterostructure with molar ratio of TiO(2) and AgNO(3) of 4:1 exhibited best photocatalytic activity and the corresponding apparent first-order rate constant of 0.138 min(-1) which is 4 times than that of pure n-type microsphere.
通过将 p 型 Ag2O 纳米颗粒组装到 n 型 TiO2 3D 微球上，制备出了 II 型 p-n 结三维 Ag2O/TiO2 微球。通过在 180°C 下水热合成 TiO2 微球，然后用光还原 AgNO3，得到了 Ag2O/TiO2 微球纳米异质结。通过 X 射线衍射（XRD）、透射电子显微镜（TEM）、场发射扫描电子显微镜（FESEM）和能谱分析（EDX）对样品进行了仔细的表征。研究了在紫外光下对甲基橙（MO）水溶液的光催化降解活性。结果表明，与 n 型 TiO2 微球相比，II 型 p-n 纳米异质结 Ag2O/TiO2 显著增强了光催化降解性能。发现光催化降解遵循准一级反应模型。特别是，TiO2 和 AgNO3 的摩尔比为 4:1 的异质结构表现出最佳的光催化活性，相应的表观一级速率常数为 0.138 min-1，是纯 n 型微球的 4 倍。
