Properties and Photocatalytic Activity of Rutile TiO$lt;inf$gt;2$lt;/inf$gt; Nanosheets

Abstract

金红石二氧化钛纳米片的性质及其光催化活性 赵丹丹, 于彦龙, 高东子, 曹亚安 (南开大学 物理科学学院, 泰达应用物理研究院, 弱光非线性光子学教育部重点实验室, 天津 300457) 摘 要: 采用溶胶-凝胶、质子交换和层状剥离的方法, 制备出金红石 TiO 2 纳米片。利用 X 射线电子衍射谱(XRD)、 透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、X 光电子能谱(XPS)的价带谱和荧光光谱(PL)等对样品进行 了表征, 研究了光生载流子的转移过程。结果证明: 金红石 TiO 2 纳米片具有较大的比表面积(185.7 m 2 /g), 厚度约 5 nm, 与金红石 TiO 2 样品相比, 金红石 TiO 2 纳米片的禁带宽度增加, 氧化还原能力增强; 此外, 纳米片结构能够促 使光生载流子快速转移到纳米片的表面并产生有效分离, 阻止了光生电子和空穴的复合, 提高了光催化反应中光 生载流子的利用率。 金红石纳米片的这些特性导致其具有较高的光催化活性, 紫外光催化降解对氯苯酚的实验表明: 金红石 TiO 2 纳米片的光催化活性高于金红石 TiO 2 和锐钛矿 TiO 2 样品。 关 键 词: 金红石 TiO 2 纳米片; 比表面积; 能带结构; 光生载流子; 光催化活性 中图分类号: O643; O644文献标识码: A Abstract: Rutile TiO 2 nanosheets were prepared by Sol-Gel method, proton exchange and delamination method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis diffuse reflectance spectroscope, X-ray photoelectron spectroscope (XPS) and photoluminescence (PL). The transference of photogenerated charge carriers was studied. It is revealed that the rutile TiO 2 nanosheets (thickness 5 nm) exhibit increased specific surface area (185.7 m 2 /g) and enlarged energy band gap, resulting in enhanced redox ability, when compared with rutile TiO 2 samples. In addition, the photogenerated charge carriers are able to transfer to the surface of nanosheets, due to their unique structure enabling photogenerated charge carriers to be effective separation during photocatalytic reactions. Therefore, the rutile TiO 2 nanosheets can enhance photocatalytic activity. Forthermore, the rutile TiO 2 nanosheets exhibite higher photocatalytic activity than rutile and anatase TiO 2 samples on the photocatalytic degradation of 4-chlorophenol under ultraviolet irradiation.

Constructing the Vo-TiO2/Ag/TiO2 Heterojunction for Efficient Photoelectrochemical Nitrogen Reduction to Ammonia

“…The deconvolution of the O 1s XPS spectrum yielded two obviously different atomic orbital characteristic peaks (Figure d). The peak at 529.8 eV can be assigned to the lattice oxygen while the peak at 530.9 eV belonged to the surface adsorption of the −OH group induced by an oxygen vacancy . The delocalized electrons caused by the oxygen vacancy is confirmed by electron paramagnetic resonance (EPR) spectroscopy.…”

“…The peak at 529.8 eV can be assigned to the lattice oxygen while the peak at 530.9 eV belonged to the surface adsorption of the −OH group induced by an oxygen vacancy. 46 The delocalized electrons caused by the oxygen vacancy is confirmed by electron paramagnetic resonance (EPR) spectroscopy. Compared with annealed anatase TiO 2 , black V o -TiO 2 showed a strong electron spin signal at g = 2.001 (Figure S5), indicating that TiO 2 prepared by solvothermal method was rich in inherent oxygen vacancy and Ti 3+ ions, which was in accordance with the results of XPS.…”

One-step Synthesis of Black TiO2 Composite Coating on Glass by Pulsed Laser Spraying

“…激发光源, 在其表面产生氧化能力极强的光生空穴, 能够将大部分有机物彻底氧化分解为二氧化碳和水, 在诸如废水处理、空气净化等方面得到了广泛应用, 因此纳米二氧化钛的光催化技术日益成为国内外研 究的热点 [1][2][3] 。然而, 自然光中的紫外波段光能量占 比小, 严重限制了二氧化钛的光催化效率 [4] 。 近年来, 一些学者通过掺杂、氢化、高能脉冲激光辐照等方 法制备了黑色纳米二氧化钛, 成功地达到了缩小带 宽、提高光能利用率和催化效率的目的 [5][6][7] 。 纳米二氧化钛粒径极小, 在实际应用中存在回 收困难、易聚集等缺点, 因此必须将其负载在其他 材料上使用 [8] 。 然而, 目前鲜见将黑色纳米二氧化钛 的制备与负载一步合成的研究。 脉冲激光溅射沉积技术是将高功率脉冲激光聚 焦作用于靶材表面, 使靶材表面产生高温及烧蚀, 并进一步产生高温高压等离子体, 这种等离子体定 向局域膨胀, 在基片上沉积形成薄膜 [9] 。近年来, 该 技术在薄膜制备中得到了广泛关注与认可。然而, 该技术也存在薄膜制备平均沉积速率较慢, 且由于 激光引起爆炸喷溅形成熔融小颗粒等关键问题, 限 制了其在薄膜制备领域的进一步推广和应用 [10] [11][12] 。 Ti 3+ 的存在会在导带边缘以下 0.8~1.0 eV 处形成 一个局部态, 缩短了二氧化钛的禁带宽度, 增加了 对可见波段光的吸收, 外观颜色表现为黑色。这将 有助于提高光催化能力 [13][14] 。 图 7 XPS 测试谱图 Fig. 7…”