Titanium Dioxide Photocatalyst Toward High Sensitivity and Visible light Sensitivity

二氧化钛是一种高效的光催化剂，其应用领域已扩展到自洁建筑材料和环保技术等方面。然而，它只能被紫外线（UV）照射激活，因此需要修改其对可见光的灵敏度。因此，在TiO_2中掺入外来元素成为研究的热点，氮掺杂TiO_2也受到了广泛的关注。我们成功制备了不同程度掺杂氮、碳和硫的TiO_2，并对其可见光诱导活性进行了评价。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（DOSs），引入的阴离子p或bit在禁带内也形成了局域电子态。在Ta、N共掺杂TiO_2体系中，利用DOS计算设计了n2p能级向价带（正电位）方向移动，并通过混合价带导致n2p能级的离域。因此，我们可以预期Ta， n共掺杂TiO_2具有较高的活性，这是由于在可见光照射下氧化能力和空穴迁移率增加。事实上，Ta、n共掺杂TiO_2比单纯n掺杂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化氧材料对有机化合物的氧化分解。我们研究了各种新型光催化剂，控制电子能带结构和晶体结构。例如，我们已经报道了具有ReO_3结构的Ag ‘ -插入NbO_2F和具有利用Ag ’的沉积结构的α- ag高_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。这有利于提高可见光灵敏度和光催化活性，因为Ag4d与O2p的混合降低了带隙能量，分散的价带导致了光生成孔的高迁移率。除了d^0、d^<10>、d^<10>s^2构型中的Ag’阳离子和阴离子，如Cu’、Pb^2等，都可以生成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O2p轨道配体调制闭合壳层和寻找有利于空穴迁移的晶体结构。少

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