TiO2表面光催化基元过程

在过去的几十年里，得益于二氧化钛(TiO₂)作为光催化剂在光催化分解水、污染物降解方面的潜在应用，人们对TiO₂光催化剂的开发、改良以及TiO₂表面光催化机理的基础研究方面都投入了巨大的精力。因此，在超高真空环境下，利用不同的实验和理论方法，人们对TiO₂表面(特别是金红石TiO₂(110)表面)的热催化和光催化过程进行了大量的研究，以此来获得上述重要反应中的一些机理性的信息。本文中，将从TiO₂的物质结构以及电子结构开始，然后着重介绍TiO₂表面光生电荷(电子和空穴)的传输、捕获以及电子转移动力学方面的进展。在此基础上，总结了甲醇在金红石TiO₂(110)、TiO₂(011)以及锐钛矿TiO₂(101)表面光化学基元反应过程的一些实验结果。这些结果不仅能增进我们对表面光催化基元过程的认识，同时也能激励我们进一步去研究表面光催化基元过程。最后，基于现有光化学实验结果，简短地讨论了我们对光催化反应机理的一点看法，并提出了一个可能的光催化模型，这可以引起人们对光催化反应机理更全面的思考。

Fundamental Processes in Surface Photocatalysis on TiO2

Because of the potential applications of TiO₂ in photocatalytic hydrogen production and pollutant degradation, over the past few decades we have witnessed increasing interest in and effort toward developing TiO₂-based photocatalysts, and improving the efficiency and exploring the reaction mechanisms at the atomic and molecular levels. Because surface science studies on single crystal surfaces under ultrahigh vacuum (UHV) conditions can provide fundamental insights into these important processes, both the thermo-and photo-chemistry on TiO₂, especially on rutile TiO₂(110) surfaces, have been extensively investigated with a variety of experimental and theoretical approaches. In this review, commencing with the properties of TiO₂, we then focus on charge transport and trapping, and electron transfer dynamics. Next, we summarize recent progress made in the study of elementary photocatalytic chemistry of methanol on mainly rutile TiO₂(110), as well as in some studies on rutile TiO₂(011) and anataseTiO₂(101). These studies have provided fundamental insights into surface photocatalysis and stimulated new investigations in this exciting area. The implications of these studies for the development of new photocatalysis models are also discussed.