Preparation of Transition Metal Doped Titania-Silica photocatalyst through Two-Liquids Phase Separation

双液相分离制备过渡金属掺杂二氧化钛-二氧化硅光催化剂

• 批准号: 11450332
• 负责人: YASUMORI Atsuo
• 金额: $ 4.16万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450332/
• 关键词: Titania; Phase separation; Photpcatalyst; Transition metal; Selective leaching; Silica; Hydrogen generation; 微粒子; 溶融; アナターゼ

In the system which has a stable two-liquid immiscibility region above its liquidus temperature, the variations of the holding temperature and the time of its melt can control the size and the composition of the phase separated texture of the quenched material. In this study, a visible light active photocatalyst, which comprises oxide semiconductor fine particles and glass matrix, was prepared through the quenching of the phase separated melt in TiO_2-SiO_2 system containing transition metal and the subsequent heat treatment and selective leaching.The Fe, Cr, V, Nb ions of 0.1-1 mass% to Ti were added to the granular TiO_2 photocatalysts comprising anatase phase which were synthesized by rapid quenching of phase-separated 40TiO_2-60SiO_2 (mass%) melts and subsequent selective reaching. The phase of TiO_2 was examined by XRD. The photocatalytic activities of the samples were also evaluated from the hydrogen generation from 20 vol% ethanol aqueous solution under the illumination of the 500W high pressure mercury lamp.The anatase ratios to rutile in the transition metal doped samples were smaller than that in non-doped one, though the relation between the ratio and the amount of transition metal was not clear. The hydrogen generation did occur by illumination of not the visible light but UV one. The generation rates of the doped samples were one tenth to five hundredth less than that of the non-doped sample (ca. 1.5 mmol・g^<-1>・h^<-1>) , and the rate decreased with increase of the amount of transition metals. As the degre6 of phase transition from anatase to rutile was not so much in the doped samples, the degradation of photocatalytic activity is considered to occur due to the recombination of photo-excited electrons and holes at the sites of the transition metal ions in the sample.

在液线温度以上具有稳定的两液不混相区的体系中，保温温度和熔化时间的变化可以控制淬火材料相分离织构的大小和成分。本研究通过对含过渡金属的TiO_2-SiO_2体系中的相分离熔体进行淬火、热处理和选择性浸出，制备了一种由氧化物半导体微粒和玻璃基质组成的可见光活性光催化剂，并将质量分数为0.1~1%的Fe、Cr、V、Nb离子加入到含有锐钛矿相的颗粒光催化剂中。用X射线衍射仪对二氧化钛的物相进行了分析。在500W高压汞灯的照射下，样品的光催化活性由20%乙醇水溶液产生的氢气来评价。掺杂过渡金属的样品中的锐钛矿相与金红石相的比例比未掺杂的样品要小，但与过渡金属的量之间的关系不明显。氢气的产生不是通过可见光的照射，而是通过紫外线的照射。掺杂样品的生成率比未掺杂样品的生成率(约1.5 mmol.g^&lt；-1)低1/10~5%，且随着过渡金属含量的增加，生成速率降低。由于掺杂样品从锐钛矿到金红石的相变程度较小，光催化活性的下降可能是由于样品中过渡金属离子位置的光激发电子和空穴的复合所致。