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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是一种高效的光催化剂，其应用领域已扩展到自清洁建筑材料和环境保护技术等方面。然而，它只能通过紫外光（UV）照射激活，因此需要改变其对可见光的敏感性。因此，在TiO_2中掺杂杂质元素成为研究热点，氮掺杂TiO_2受到了广泛的关注.我们成功地制备了氮、钙钛矿和硫掺杂的TiO_2，并对其可见光诱导活性进行了评价。但阴离子掺杂的TiO_2在可见光照射下活性较低。考虑到掺杂态密度（DOS），引入的阴离子-p或阴离子-位在禁带中形成局域电子态是合理的。用DOS计算设计了Ta，N共掺杂TiO_2体系中N2 p能级向价带（正电势）移动， ...更多信息导致N 2 p能级通过价带混合而离域。可见光照射下，Ta，N共掺杂的TiO_2具有较高的光催化活性，这主要是由于Ta，N共掺杂提高了TiO_2的氧化能力和空穴迁移率。事实上，Ta，N共掺杂的TiO_2比单独N掺杂的TiO_2具有更高的催化活性。除TiO_2基材料外，只有少数报道研究了氧化物或氮氧化物材料对可见光敏感的有机物的氧化分解。我们已经研究了各种这样的新型光催化剂，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 ′插入的具有ReO_3结构的NbO_2F和具有铜铁矿结构的α-AgGaO_2。4d^构型的Ag′阳<10>离子混合O2 p轨道，形成高度分散的上价带。这对于可见光灵敏度和高光催化活性是有利的，因为Ag 4d与O2 p的混合降低了带隙能量，并且分散的价带导致光生空穴的高迁移率。除了Ag′阳离子和d^0、<10>d^2、d^s^2<10>构型的阴离子，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O2 p轨道调制封闭壳层并找到有利于空穴迁移的晶体结构。少