二氧化钛纳米棒的制备及其晶体生长机理分析

采用溶剂热法合成具有高结晶性与单分散性的TiO₂纳米棒. 采用TEM、XRD、HRTEM等对样品的微观结构进行表征, 并考察了TiO₂纳米棒对亚甲基蓝的光催化性能. 通过控制反应时间、反应温度, 研究纳米棒的形貌演变规律.结果表明, 可以通过“奥斯特瓦尔德熟化”和“取向接触”两种晶体生长过程制备出棒状TiO₂纳米晶, 降低纳米晶的表面能是晶体生长与形貌演变的主要驱动力; 高结晶性的TiO₂纳米棒具有高于P25的光催化能力.

Synthesis and Crystal Growth Mechanism of Titanium Dioxide Nanorods

Highly crystalline and monodisperse anatase TiO2 nanorods were synthesized successfully via an improved solvothermal method.The shape evolution of TiO2 nanorod was investigated by adjusting the reaction parameters,such as reaction duration and temperature.The phase structures,morphologies,and sizes of as-prepared TiO2 nanoparticles were investigated in detail by XRD,TEM,and HRTEM.The photocatalytic properties of the product were measured by decomposition of methylene blue under full spectrum light irradiation.When Ostwald Ripening is dominant,the TiO2 nanorods grow along the <001> crystallographic direction.When Ostwald Ripening is depressed at lower temperature,Oriented Attachment occurs.And primary nanoparticles join together by sharing a common(001) facet.The driving force of shape evolution and crystal growth of TiO2 nanocrystals is reducing the high surface free energy.Compared with P25,the as-prepared TiO2 nanorods exhibit a superior photocatalytic activity,which is attributed to the high crystallinity.