锐钛矿和金红石型TiO <sub>2的</sub>光致发光机理<sub></sub>,The Journal of Physical Chemistry C

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锐钛矿和金红石型TiO _2的光致发光机理
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-04-14 00:00:00 , DOI: 10.1021/acs.jpcc.7b00321
Deborah K. Pallotti ₁ , Luca Passoni _{2,

3} , Pasqualino Maddalena ₄ , Fabio Di Fonzo ₂ , Stefano Lettieri ₁

Affiliation

光致发光（PL）代表了一种探测光催化材料中分子吸附和表面反应的灵敏工具。二氧化钛（TiO ₂）是使用最广泛的光催化方法之一，阐明其基本PL机理可以提供重要的信息。然而，与其他电子和表面工艺不同，TiO ₂的实际PL机理尚未得到广泛研究。在这项工作中，我们通过重点研究触发PL活性的不同状态以及确定在两种稳定的TiO _2中起作用的特定重组途径来解决这一问题。多晶型物（金红石和锐钛矿）。根据我们关于PL发射，PL激发以及氧诱导的和光诱导的PL修饰的实验结果，我们为两种多晶型物绘制了一个解释方案。由分子氧引起的激发分辨的PL和重组猝灭证明了对锐钛矿PL的独特贡献，这分别归因于我们分别归因于表面和地下氧空位的不同种类的空穴俘获和电子俘获缺陷。对金红石PL讨论了两种可能的机制，包括位于氧原子处的自陷空穴或占据位于费米能级以下的中能隙态的被俘获电子。我们认为，前一种机制的有效性暗示着自陷孔在远离金红石表面的地方有效地形成了，

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Photoluminescence Mechanisms in Anatase and Rutile TiO2

Photoluminescence (PL) represents a sensitive tool for probing molecular adsorption and surface reactions in photocatalytic materials. Titanium dioxide (TiO₂) is one of the most widely used photocatalysis, and clarifying its basic PL mechanism can give important information. However, differently from other electronic and surface processes, the actual PL mechanisms of TiO₂ are not extensively studied. In this work, we address the topic by focusing our investigation on which are the different states that trigger the PL activity and on identifying the specific recombination pathways acting in the two stable TiO₂ polymorphs (rutile and anatase). On the basis of our experimental results on PL emission, PL excitation, and oxygen-induced and photoinduced PL modifications, we sketch an interpretative scheme for both the polymorphs. Excitation-resolved PL and recombination quenching caused by molecular oxygen evidence distinct contributions to anatase PL, originating from different kinds of hole-trapping and electron-trapping defects that we ascribe to surface and subsurface oxygen vacancies, respectively. Two possible mechanisms are discussed for rutile PL, involving self-trapped holes located at oxygen atoms or trapped electrons occupying midgap states positioned below the Fermi level. We argue that the validity of the former mechanism would imply that self-trapped holes are efficiently formed far from the rutile surface, while the latter mechanism seems more plausible although the very nature of the involved midgap electron state still has to be clarified.

更新日期：2017-04-14

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