The Role of Photoinduced Defects in TiO2 and Its Effects on Hydrogen Evolution from Aqueous Methanol solution

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• 作者：Xiaoyi Yang ; Christoph Salzmann ; Huahong Shi ; Hongzhi Wang ; Malcolm L. H. Green ; Tiancun Xiao
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：October 30, 2008
• 年：2008
• 卷：112
• 期：43
• 页码：10784-10789
• 全文大小：219K
• 年卷期：v.112,no.43(October 30, 2008)
• ISSN：1520-5215

文摘

The hydrogen evolution from aqueous methanol solutions was found to follow two stages of zero order kinetics during photoreactions using TiO₂ as the photocatalyst. Maximal hydrogen evolution was found at the 10% (v/v) methanol solution. X-ray photoelectron spectroscopy (XPS) shows that Ti(1566) defects are formed on the surface of TiO₂ and X-ray powder diffraction (XRD) indicates that Ti(1566) defects are also formed in the bulk after photoreaction. Formation of defects is also shown by broadening of Bragg peaks and blue shifts and peak broadening in Raman spectroscopy. The defect disorder results in the increase of hydrogen evolution. UV−vis diffuse reflection spectra confirm that new absorptions in the visible light region are related to the defect content. At high methanol concentration, XPS implies that the active sites of the surface are blocked by hydroxyl groups, which results in the decrease of hydrogen evolution. TEM images showed that the photoreaction occurred on the surface of the photocatalyst as the surface of the TiO₂ became rough after the photoreaction.