Thin carbon layer coated Ti3+-TiO2 nanocrystallites for visible-light driven photocatalysis
Thin carbon layer coated Ti3+-TiO2 nanocrystallites for visible-light driven photocatalysis
复制标题
用于可见光驱动光催化的薄碳层涂覆的 Ti3-TiO2 纳米晶
DOI：
10.1039/c5nr00032g
复制
发表时间：
2015
期刊：
影响因子：
6.7
通讯作者：
Honggang Fu
中科院分区：
文献类型：
--
作者：
Baojiang Jiang;Yunqi Tang;Yang Qu;Jian-Qiang Wang;Ying Xie;Chungui Tian;Wei Zhou;Honggang Fu
含Ti3+的黑色TiO2因其优异的可见光催化活性而引起人们的极大关注。本文提出了一种原位热分解法制备均匀薄碳包覆Ti3 +-TiO2纳米晶。在油酸辅助溶剂热过程中，通过油酸与羧酸基团控制二氧化钛的晶体尺寸和形貌。然后将少量的油酸作为碳源，在高温和惰性气氛下原位热解在TiO2表面形成碳层。同时，碳包覆Ti3 +-TiO2结构中的Ti4+物种由于碳热还原反应而部分还原为Ti3+态/TiO2表面的氧空位。一系列表征表明，所制备的20-25 nm的TiO2纳米晶被1-2 nm的碳层均匀包裹，这对TiO2能带结构的变化有重要影响。碳层的存在也改善了复合材料的Ti 3+稳定性和导电行为。TiO2表面产生的Ti3+态/氧空位是导致光生电荷分离和可见光吸收范围扩大的主要原因。此外，Ti3+态/氧空位和碳层的共同作用可以增强O2的吸附能力，从而促进光生电子被吸附的O2捕获，导致电荷分离大大增加。结果表明，该复合材料在可见光照射下对有机污染物具有良好的光催化性能。这种简单的新方法可能为可见光下高效光催化降解的实际应用铺平道路。
Black TiO2 containing Ti3+ attracts enormous attention due to its excellent visible-light driven photocatalytic activity. Herein, an in situ thermal decomposition approach to synthesize uniform thin carbon coated Ti3+-TiO2 nanocrystals is presented. During the oleic acid-assisted solvothermal process, the crystal size and morphology of TiO2 were controlled through oleic acid with carboxylic acid groups. Then the residual small quantities of oleic acid anchored on TiO2 were used as a carbon source, which could be in situ pyrolyzed into a carbon layer on TiO2 at high temperature and under an inert atmosphere. Meanwhile, Ti4+ species were partly reduced into Ti3+ states/oxygen vacancies on the surface of TiO2 due to the carbothermal reduction reaction for the carbon-encapsulated Ti3+-TiO2 structure. A series of characterizations indicated that the 20–25 nm TiO2 nanocrystals obtained were wrapped evenly by 1–2 nm carbon layers, which had an important effect on the energy band structure change of TiO2. The presence of the carbon layer also improves the Ti3+ stability and the conduction behavior of the composites. The Ti3+ states/oxygen vacancies created on the surface of TiO2 were responsible for the remarkable photogenerated charge separation and extended visible-light absorption range. Furthermore, Ti3+ states/oxygen vacancies and the carbon layer together could enhance the adsorption ability of O2 so as to promote the photogenerated electrons captured by the adsorbed O2, leading to a great increase in the charge separation. As a result, the composites exhibit high photocatalytic performance for organic pollutants under visible light irradiation. This simple and new method may pave the way to practical applications for efficient photocatalytic degradation under visible light.