Department of Physics, University of the Free State , Bloemfontein 9300, South Africa.
ACS Appl Mater Interfaces. 2017 Aug 30;9(34):28495-28507. doi: 10.1021/acsami.7b07571. Epub 2017 Aug 16.
There is a growing interest in multifunctional nanomaterials for the detection as well as degradation of organic contaminants in the water. In this work, we report on the development of dual functional TiO nanofibers (TNF) with different tantalum (Ta) doping (1-10 mol %) by a simple electrospinning technique. As-prepared TNF show mesoporous dominant structure, which are favorable for photocatalytic activity due to the presence of catalytic spots. Ta doping decreases the crystalline size within TiO matrix because of the incorporation of Ta ions and restricts the phase transformation from anatase to rutile. Ta doping slightly enhances the visible light absorption because of the Ti defects sites created upon Ta doping. The effect of Ta doping within TiO matrix was systematically studied for the degradation of methylene blue (MB) dye under ultraviolet (UV) and solar light irradiation. The 5% Ta-doped TNF were found to be optimal and showed 5.1 and 2.2 times higher photocatalytic activity as compared to TNF under UV and solar light irradiation, respectively. The effect of Ta doping for the detection of MB molecules was also studied by surface enhanced Raman scattering (SERS). It was observed that 5% Ta-doped TNF exhibit higher photocatalytic activity and enhanced SERS signals of adsorbed MB molecules as compared to the TNF. The enhanced photocatalytic and SERS activities can be explained as combined effects of enhanced visible light absorption, lower crystalline size, and slightly higher surface area. The observed results show that Ta doping induces new energy levels below the conduction band of TiO because of Ti defects, which inhibit the photogenerated charge recombination acting as electron traps and promote charge transfer mechanism acting as an intermediate state for TiO to MB molecule electron transfer, and are mainly responsible for the enhanced photocatalytic and SERS activities, respectively.
人们对多功能纳米材料越来越感兴趣，这些材料可用于检测和降解水中的有机污染物。在这项工作中，我们通过简单的静电纺丝技术报告了不同钽（Ta）掺杂（1-10 mol%）的双功能 TiO2 纳米纤维（TNF）的开发。所制备的 TNF 具有介孔为主的结构，由于存在催化点，因此有利于光催化活性。Ta 掺杂由于 Ta 离子的掺入而降低了 TiO 基质中的晶粒度，并限制了从锐钛矿到金红石的相转变。Ta 掺杂略微增强了可见光吸收，因为 Ta 掺杂会在 Ti 缺陷位上产生。系统研究了 Ta 掺杂对 TiO 基质中 MB 染料在紫外（UV）和太阳光照射下降解的影响。与 TNF 相比，发现 5% Ta 掺杂的 TNF 在 UV 和太阳光照射下的光催化活性分别提高了 5.1 和 2.2 倍。还通过表面增强拉曼散射（SERS）研究了 Ta 掺杂对 MB 分子检测的影响。观察到与 TNF 相比，5% Ta 掺杂的 TNF 表现出更高的光催化活性和吸附 MB 分子的增强 SERS 信号。增强的光催化和 SERS 活性可以解释为增强的可见光吸收、更低的结晶度和稍高的比表面积的综合影响。观察到的结果表明，由于 Ti 缺陷，Ta 掺杂在 TiO 的导带下方诱导出新的能级，从而抑制光生载流子复合，作为电子陷阱起作用，并促进电荷转移机制，作为 TiO 到 MB 分子电子转移的中间态起作用，分别是增强光催化和 SERS 活性的主要原因。
