模拟光合作用的大比表面积、高结晶度超长TiO2纳米纤维光催化材料制备

Photocatalytic reaction has been studied since the photolysis of water by TiO2 photocatalyst in 1972, and the photo-generated holes or OH radicals can be powerfully oxidized species to decompose and mineralize a large variety of organic compounds. However, the problems such as separation, recovery, and activities of TiO2 or titanate photocatalyst still remain as a challenge. To solve the problems of separation and recovery of the large surface area nanostructure photocatalyst, free standing membrane from long catalytic titanate nanowire would be synthesized, and concurrent filtrate and photocatalytic oxidize of pollutants can be easily realized in aqueous solution. To improve the photocatalyst property of nanosized TiO2 or titanate, modification of the band gap of TiO2 by sensitizing with dyes would be developed. Metal porphyrin may be an appropriate candidate among these dyes because of its high absorption coefficient within the solar spectrum and its good chemical stability in comparison to that of other dyes. In this proposal, a confined envioment and controlled pressure hydrothermal method would be developed to prepare ultra-long titanate nanowire catalysts, and then modified the metal porphyrin on the catalytic nanowire. Finally, the free-standing-membrane or the FSM-based 3D devices would be fabricated. We will investigate the TiO2 long nanowire membrane photocatalyst sensitized with Metal porphyrin to degrade acid chrome blue Kunder visible light irradiation. By injecting electrons from the photoexcited sensitizer to the conduction band, the sensitized TiO2 nanowire degraded acid chrome blue K under incandescent lamp irradiation.

本课题发展反应空间限域与动态调整的水热合成方法，实现大比表面积和高结晶度一维超长TiO2纳米纤维的定向生长与组装；在原子或分子水平上认识一维纳米材料的成核、生长机制以及一维纳米结构与新性质的关系。模拟光合作用，采用卟啉敏化方法修饰TiO2纳米纤维，研究卟啉光敏TiO2纳米纤维体系的能量转换和能带结构与反应物的电极电位及可见光能量的匹配，减少电子和空穴的复合几率。使得对可见光谱的吸收大大增加，实现可见光催化并提高光催化效率。利用卟啉敏化的TiO2纳米纤维组装高效稳定的、自支撑的、多孔的从紫外光至可见光都有响应的无机纳米纤维薄膜，此薄膜在水处理领域可同时实现过滤薄膜和光催化薄膜的双重作用。

随着光催化技术的发展和进步，以二氧化钛为主要的光催化剂存在着一系列的问题，例如太阳光利用率低，光量子效率较低，已不能满足现阶段的环境治理要求。因此需微观尺度上设计和制备活性更高，光响应范围宽的光催化剂。以二氧化钛和贵金属为基础进行改性，并探讨不同制备条件如沉积时间，电压等因素对改性后光催化剂结构和性能的影响；在二氧化钛的基础上，我们延伸到钛酸盐半导体的制备，在制备过程中改变反应条件，成功地制备出一些不同形貌的钛酸盐纳米材料并对制得的钛酸盐纳米材料进行了一定的性能研究。同时在上述基础上，也独创制备了石墨烯贵金属层状结构复合材料，在此基础上进行了对4-NP的降解和重复利用率的探究。. 本项目的意义在于微观尺度上从结构和功能揭示材料的光催化本质，并在此基础上通过改性提高催化剂的催化性能，为开发新型的光催化剂提供理论支持和实验基础。