[2010年12月1日]

BiVO4光催化剂氧化水研究取得新进展

 

    

    目前光催化分解水领域大部分的研究工作集中在产氢的半反应,然而在分解水的过程中水氧化是一个更加挑战的反应, 因为该过程涉及到一个四电子转移过程而且是一个自由能远远高于零的爬坡反应。为了得到更高的光催化分解水的效率,更好的理解水氧化反应和开发高效的水氧化催化剂是非常必要的。此外,半导体光催化剂的光催化活性受直接暴露在溶液环境中的表面结构影响。在过去的几十年,表明科学家已经在催化剂晶面的化学性质方面做了很多努力。

    最近我组王冬娥同学等采用微量的TiCl3作为导向剂水热合成高暴露 (040) 面的单斜晶相BiVO4。具有高暴露(040)面的BiVO4光催化剂可以通过调变TiCl3导向剂加入量和水热的pH值制备。利用BiVO4光催化剂氧化水的活性可以与(040)面的暴露程度很好地进行关联。从原子结构示意图分析发现(040)面可以提供多原子BiV4中心,该中心可能是光催化氧气生成的活性位。我们的发现表明可控合成具有某一特定活性晶面的光催化剂是提高光催化活性的一种有效途径。
 

Article

Crystal Facet Dependence of Water Oxidation on BiVO4 Sheets under Visible Light Irradiation

Donge Wang, Hongfu Jiang, Xu Zong, Qian Xu, Yi Ma, Guoling Li and Can Li*

Chem. Eur. J., 2010, DOI: 10.1002/chem.201001636

 http://dx.doi.org/10.1002/chem.201001636

 

Abstract

Monoclinic BiVO4 crystals with preferentially exposed (040) facets were hydrothermally synthesized by using a trace amount of TiCl3 as the directing agent; this function was confirmed by X-ray diffraction patterns (XRD) and high-resolution transmission electron microscopy (HRTEM). The effects of the directing agent TiCl3 and the pH values applied during synthesis have been studied, and the optimized BiVO4 sample with highly exposed (040) facet could be obtained by using 1.2 at.% of TiCl3 as the directing agent at a pH value of 2. Some complementary techniques were also applied to exclude the effects of the structural and physical property changes, such as surface area and hydrophilicity. The photocatalytic activity of oxygen evolution on BiVO4 is found to be proportionally correlated with the exposed surfaces of the (040) facet. It is assumed that the active sites with a BiV4 structure on the exposed (040) facet is assigned to be responsible for the high activity of O2 evolution.

 

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