DESIGN OF NEW PHOTOFUNCTIONAL MATERIALS BASED ON EXFOLIATED TWO DIMENSIONAL OXIDES

从生态友好的角度来看，光催化剂近年来引起了人们的极大关注。然而，已经发现的光催化剂不能利用占主导地位的太阳光的可见光。虽然发现了几种材料如CdS利用可见光，但它们的生态危害性质是最大的缺点。我们发现，可离子交换的过渡金属氧化物是一种很有前途的催化剂，在可见光区具有光响应。这些材料的严重问题是它们的高层间电子密度抑制了反应物的嵌入，并且层间空间没有被有效地利用。另一方面，使用有机离子如三丁基铵离子（TBA+）的插层使得层的剥离能够产生高度分散在水中的大聚阴离子片。此外，分散的二维无机薄片被发现是微孔材料和无机薄膜的起始材料。这些新材料表现出比原始过渡金属氧化物更高的光活性，并显示出不同的化学性质。合成了新型的层状材料，有望作为功能材料应用。

Photocatalysts recently attract a great attention from the view point of eco-friendliness. However, already found photocatalysts do not avail the visible light which dominates the solar light. Although several materials such as CdS were found to utilize the visible light, the eco-harm nature of them is the great disadvantage. We have found that the ion-exchangeable transition metal oxides are promising catalysts which have the photoresponse in visible light region. The serious problem of those materials are that their high interlayr electron density inhibit the intercalation of reactants and that the interlayr spase has not been efficiently utilized. On the other hand, the use of intercalation of organic ions such as tri-butyl-ammonium ion (TBA+) enabled the exfoliation of the layr to produce macropolyanion sheets highly dispersed in water. Furthermore, the dispersed two dimensional inorganic sheets were found to be starting materials of microporous materials and inorganic thin films. These novel materials demonstrated higher photoactivity than the original transition metal oxide and showed different chemical nature. The new types of layred materials were synthesized and are expected to be utilized as functional materials.