Hyam Rajeshkumar Shankar, Lee Jongseok, Cho Eunju, Khim Jeehyeong, Lee Haigun
Department of Materials Science and Engineering, Korea University, Seoul 136-701, Korea.
J Nanosci Nanotechnol. 2012 Dec;12(12):8908-12. doi: 10.1166/jnn.2012.6734.
In the present study, amorphous titanium dioxide (TiO2) nanotubes were synthesized by one-step anodization technique and subsequently annealed in different environments to investigate the effect of annealing atmospheres on the formation of different crystalline phases. X-ray Diffraction (XRD) patterns clearly showed the presence of anatase TiO2 phase with various crystallite sizes. The samples annealed in oxygen and air atmospheres at 500 degrees C showed a dominant anatase phase and a small amount of rutile phase, on the other hand, the samples annealed in nitrogen and argon atmospheres and in a vacuum at 500 degrees C contained the anatase phase only. XPS analysis of the samples showed a broadening in the binding energy curves with respect to variation in annealing atmosphere, confirming the variation in surface defects, which in turn affect photocatalytic degradation. The vacuum-annealed sample showed superior photocatalytic degradation efficiency as it had relatively higher pseudo-first order rate constants (k) of 0.009/min.
在本研究中，通过一步阳极氧化技术合成了非晶态二氧化钛（TiO₂）纳米管，随后在不同环境中进行退火，以研究退火气氛对不同晶相形成的影响。X射线衍射（XRD）图谱清楚地显示了具有不同晶粒尺寸的锐钛矿TiO₂相的存在。在500℃的氧气和空气气氛中退火的样品显示出主要的锐钛矿相和少量的金红石相，另一方面，在500℃的氮气和氩气气氛以及真空中退火的样品仅含有锐钛矿相。对样品的XPS分析表明，随着退火气氛的变化，结合能曲线变宽，证实了表面缺陷的变化，这反过来又影响光催化降解。真空退火样品表现出优异的光催化降解效率，因为它具有相对较高的伪一级反应速率常数（k），为0.009/分钟。
