Design and Development of Second-generation TiO2 Photocatalyst Operating under Solar Beam Irradiation for the Decomposition of NOx

太阳光照射下分解氮氧化物的第二代TiO2光催化剂的设计与开发

基本信息

批准号：
09555272
负责人：
ANPO Masakazu
金额：
$ 6.85万
依托单位：
Osaka Prefecture University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

In this research project, the design and development of TiO_2 photocatalysts which can absorb visible light and operate efficiently and effectively not only under ultraviolet light but also upon irradiation with visible light or solar beam for the decomposition of NO into N_2 and 0_2 were carried out. Until now, photocatalytic reactions involving TiO_2 photocatalysts for the decomposition reaction of nitrogen oxides (NOx) in the atmosphere are known to proceed only under irradiation of TiO2 photocatalysts with ultraviolet light having shorter wavelength than 380nm, allowing the use of 3% of solar beam. In order to use solar beam more efficiently, we have elucidated the modification of TiO_2 photocatalyst by applying the advanced metal ion-implantation with various transition metal ions such as Cr highly accelerated by high voltage. A combination of such metal ion-implantation and the subsequent calcination of the catalyst in oxygen at around 723 K enables a large shift in the absorption bands of TiO_2 toward visible-light regions, its extent depending on the amount of Cr ions implanted. Such Cr ion-implanted TiO_2 catalysts successfully decompose NO into N_2, 0_2 and N_2O even at 275 K under irradiation with visible light longer than 450nm. Furthermore, the reaction proceeded at exactly the same rate to that of the unimplanted TiO_2 catalysts under band-gap UV light irradiation. Under outdoor solar light irradiation at ordinary temperatures, the Cr ion-implanted TiO_2 catalyst exhibited photocatalytic reactivity several times higher than the original unimplanted TiO_2 photocatalyst. It can be said that present research has opened the way to many innovative possibilities, significantly to address urgent environmental problems, and can also be considered an important breakthrough in the utilization of solar energy.

在本研究项目中，设计和开发了TiO_2光催化剂，该催化剂可以吸收可见光，不仅在紫外光下而且在可见光或太阳光束照射下高效有效地将NO分解为N_2和0_2。迄今为止，已知涉及TiO_2光催化剂的大气中氮氧化物(NOx)分解反应的光催化反应仅在TiO2光催化剂用波长短于380nm的紫外光照射下进行，允许使用3%的太阳光束。为了更有效地利用太阳光束，我们通过应用先进的金属离子注入技术，在高压下高度加速Cr等各种过渡金属离子，阐明了TiO_2光催化剂的改性。这种金属离子注入和随后在约 723 K 的氧气中煅烧催化剂的组合使得 TiO_2 的吸收带向可见光区域发生很大的转变，其程度取决于注入的 Cr 离子的量。这种Cr离子注入的TiO_2催化剂即使在275 K、长于450nm的可见光照射下也能成功地将NO分解为N_2、0_2和N_2O。此外，在带隙紫外光照射下，反应以与未注入的TiO_2催化剂完全相同的速率进行。在常温下的室外太阳光照射下,Cr离子注入的TiO_2催化剂表现出比原始未注入的TiO_2光催化剂高数倍的光催化活性。可以说，目前的研究开辟了许多创新的可能性，对解决紧迫的环境问题具有重要意义，也可以被认为是太阳能利用的重要突破。