Characterization of Oxygen Vacancy Associates within Hydrogenated TiO2: A Positron Annihilation Study

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• 作者：Xudong Jiang ; Yupeng Zhang ; Jing Jiang ; Yongsen Rong ; Yancheng Wang ; Yichu Wu ; Chunxu Pan
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：October 25, 2012
• 年：2012
• 卷：116
• 期：42
• 页码：22619-22624
• 全文大小：402K
• 年卷期：v.116,no.42(October 25, 2012)
• ISSN：1932-7455

文摘

This paper introduces a novel method for characterizing the oxygen vacancy associates in hydrogenation-modified TiO₂ by using a positron annihilation lifetime spectroscopy (PALS). It was found that a huge number of small neutral Ti³⁺鈥搊xygen vacancy associates, some larger size vacancy clusters, and a few voids of vacancy associates were introduced into hydrogenated TiO₂. The defects blurred the atomic lattice high-resolution transmission electron microscopy (HRTEM) images and brought about the emergence of new Raman vibration. X-ray photoelectron spectroscopy (XPS) measurement indicated that the concentration of oxygen vacancies was 3% in the TiO₂ lattice. The photoluminescence (PL) spectroscopy, photocurrent, and degradation of methylene blue indicated that the oxygen vacancy associates introduced by hydrogenation retarded the charge recombination and therefore improved the photocatalytic activity remarkably.