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Titanium Dioxide Photocatalyst Toward High Sensitivity and Visible light Sensitivity

二氧化钛光触媒迈向高灵敏度和可见光灵敏度

基本信息

批准号：
14050025
负责人：
HASHIMOTO Kazuhito
金额：
$ 80.9万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2006
项目状态：
已结题

项目摘要

TiO_2 is an efficient photocatalyst and its application areas have been expanded to self-cleaning building materials and environment preservation technologies, among others. However, it is activated only by ultraviolet (UV) light irradiation, so the modification of its sensitivity to visible light has been required. Hence, doping a foreign element into TiO_2 has been performed and nitrogen -doped TiO_2 has attracted much attention. We successfully fabricated nitrogen, carlbn, and sulfur doped TiO_2 with various degrees of these dopants and evaluated their visible-light induced activities. However, those anion-doped TiO_2 had low activities irradiated with visible light. It was plausible considering the density of states (DOSs) of anion-doped TiO_2 that the introduced anion-p or bit als formed the localized electronic states in the forbidden band. We designed using DOS calculation that the N 2p level shifts to ward the valence band (positive potential) in the Ta, N-codoped TiO_2 system, … More resulting in a delocalization of N 2p level by mixing its valence band. Thus, we could expect that the Ta, N-codoped TiO_2 had high activities, due to increasing oxidation power and hole mobility under visible light irradiation. In fact, the Ta, N-codoped TiO_2 showed higher activity than solely N-doped TiO_2.With the exception of TiO_2-based materials, only several reports have examined oxide or oxynitride materials that are sensitive to visible light for the oxidative decomposition of organic compounds. We have investigated various such novel photocatalysts, controlling electronic band structures and crystalline structures. For example, we have already reported Ag′-inserted NbO_2F with a ReO_3 structure and α-AgGaO_2 with a delafossite structure utilizing Ag′. Ag′ cation in a 4d^<10> configuration mixes the O2p orbitals, forming the highly dispersed upper valence band. This can be favorable for visible light sensitivity and high photocatalytic activity, because mixing Ag4d with O2p decreases in the band-gap energy and the dispersed valence band leads to high mobility of photo-generated holes. In addition to Ag′ cations and anions in d^0, d^<10>, d^<10>s^2 configurations, such as Cu′, Pb^2 etc., can generate photocatalysts that are sensitive to visible light. The key factors in realizing high-efficiency visible light sensitive photocatalysts are modulation of the closed shell with ligand O2p orbitals and finding crystal structure favorable for holes' mobility. Less

TiO_2是一种高效光催化剂，其应用领域已扩展到自清洁建筑材料和环境保护技术等。然而，它只能通过紫外线 (UV) 光照射来激活，因此需要修改其对可见光的敏感性。因此，向TiO_2中掺杂外来元素已成为人们关注的焦点。我们成功地制备了不同程度的氮、碳和硫掺杂的 TiO_2，并评估了它们的可见光诱导活性。然而，阴离子掺杂的TiO_2在可见光照射下活性较低。考虑到阴离子掺杂TiO_2的态密度(DOS)，引入的阴离子-p或位元在禁带中形成局域电子态是合理的。我们使用 DOS 计算设计，在 Ta、N 共掺杂 TiO_2 系统中，N 2p 能级向价带（正电势）移动，... 更多通过混合其价带导致 N 2p 能级离域。因此，我们可以预期，由于可见光照射下氧化能力和空穴迁移率的增加，Ta、N共掺杂的TiO_2具有高活性。事实上，Ta、N共掺杂的TiO_2比单独N掺杂的TiO_2表现出更高的活性。除了TiO_2基材料外，只有几篇报道研究了对可见光敏感的氧化物或氮氧化物材料对有机化合物的氧化分解。我们研究了各种此类新型光催化剂，控制电子能带结构和晶体结构。例如，我们已经报道了利用Ag'插入Ag'的具有ReO_3结构的NbO_2F和具有铜铁矿结构的α-AgGaO_2。 4d^<10>构型的Ag'阳离子与O2p轨道混合，形成高度分散的上价带。这有利于可见光敏感性和高光催化活性，因为 Ag4d 与 O2p 混合会降低带隙能量，并且分散的价带导致光生空穴的高迁移率。除了d^0、d^<10>、d^<10>s^2构型的Ag'阳离子和阴离子外，例如Cu'、Pb^2等，可以产生对可见光敏感的光催化剂。实现高效可见光敏感光催化剂的关键因素是用配体O2p轨道调制封闭壳层并找到有利于空穴迁移率的晶体结构。较少的