Efficient Charge Carrier Separation in l-Alanine Acids Derived N-TiO2 Nanospheres: The Role of Oxygen Vacancies in Tetrahedral Ti4 Sites
Efficient Charge Carrier Separation in l-Alanine Acids Derived N-TiO2 Nanospheres: The Role of Oxygen Vacancies in Tetrahedral Ti4 Sites
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L-丙氨酸衍生的 N-TiO2 纳米球中的有效载流子分离：四面体 Ti4 位点中氧空位的作用
DOI：
10.3390/nano9050698
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发表时间：
2019
期刊：
影响因子：
5.3
通讯作者：
Wang Jiaqiang
中科院分区：
文献类型：
--
作者：
Chen Yongjuan;Luo Xiu;Luo Yao;Xu Peiwen;He Jiao;Jiang Liang;Li Junjie;Yan Zhiying;Wang Jiaqiang
含氧空位的n掺杂TiO2在光催化方面表现出许多优点，如增强可见光吸收能力、抑制光生载流子复合等。然而，在温和的条件下制备含氧空位的n掺杂TiO2仍然是一个挑战。本文以十二烷基胺为模板，l-丙氨酸为辅助剂，合成了具有四面体Ti4+位的n掺杂TiO2纳米球。采用x射线粉末衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）和UV-Vis漫反射光谱（UV-Vis DRS）对所得样品进行了表征。结果表明，十二胺作为中性表面活性剂控制了TiO2的球形结构，而l-丙氨酸则提供了氮源。同时也证实了n掺杂TiO2中Ti4+四面体位的存在。具有四面体Ti4+位的n掺杂TiO2样品在紫外光或可见光照射下对亚甲基蓝溶液的光催化降解性能显著提高。结合时间分辨红外光谱研究表明，光催化性能的增强可能归因于大量的光生载流子和高效的电荷分离。结果表明，Ti4+四面体氧空位产生的浅层供体态除了能捕获电子外，还能有效地促进载流子的分离。
N-doped TiO2 with oxygen vacancies exhibits many advantages for photocatalysis, such as enhanced visible light absorbency, inhibition of the photogenerated charge carrier recombination, etc. However, preparation of N-doped TiO2 with oxygen vacancies under mild conditions is still a challenge. Herein, N-doped TiO2 nanospheres with tetrahedral Ti4+ sites were synthesized by using dodecylamine as template and assisted by l-alanine acids. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis diffuse reflectance spectra (UV–Vis DRS). It was found that the dodecylamine as a neutral surfactant controlled the structure of TiO2 spherical, while l-alanine acids provided a nitrogen source. The existence of tetrahedral Ti4+ sites in N-doped TiO2 was also confirmed. The N-doped TiO2 sample with tetrahedral Ti4+ sites exhibited significantly improved photocatalytic performance for degradation of methylene blue solution under UV light or visible light irradiation. A combined time-resolved infrared (IR) spectroscopy study reveals that the enhanced photocatalytic performance could be attributed to a large amount of photogenerated charge carriers and efficient charge separation. It is demonstrated that the shallow donor state produced by oxygen vacancies of tetrahedral Ti4+ sites can effectively promote separation of charge carriers besides capturing electrons.