沸石负载Mn,N共掺杂TiO2及光催化性能

为提高传统TiO₂光催化剂的可见光催化活性,本文采用溶胶-凝胶法合成了Mn,N共掺杂TiO₂光催化剂,改善了传统TiO₂光生载流子易复合的问题；进一步采用沸石作为载体对改性后的TiO₂样品进行负载,解决了传统光催化剂存在的难分离回收问题,以达到光催化剂可重复使用的目的.借助X-射线衍射仪、扫描电子显微镜、紫外分光光度计、傅立叶变换红外光谱仪等测试手段对Mn,N共掺杂TiO₂光催化剂的结构、元素组成、微观形貌和光催化降解性能进行系统分析与研究.研究结果表明,沸石负载Mn,N共掺杂TiO₂的样品较未改性的TiO₂样品具有更高的光催化降解活性,在可见光照射下,在最优掺杂条件下获得的TiO₂光催化剂在60 min内对孔雀石绿的降解率可达到97%,这主要归因于锰离子掺杂能够对TiO₂光生载流子的复合产生抑制作用,促进光生电荷分离,与此同时氮元素掺杂可有效拓宽TiO₂半导体光催化剂光响应范围.此外,经过5次循环使用后,对孔雀石绿的降解率没有较大程度的减弱,依然能够维持在88%以上,表明沸石负载Mn,N共掺杂TiO₂的样品具有较好的光催化循环稳定性.

Preparation of zeolite loaded with Mn, N co-doped TiO2 and its photocatalysis properties

In order to improve the visible light catalytic activity of traditional TiO₂ photocatalyst, Mn, N co-doped TiO₂ photocatalyst was synthesized by sol-gel method, which improved the problem of easy recombination of photogenerated carriers. Further, zeolite was used as a carrier to solve the problem of difficult separation and recovery of the conventional photocatalyst, achieving the purpose of reusable. The crystal phase structure, element composition, microtopography, and photocatalytic activity of TiO₂ photocatalyst were characterized by XRD, SEM, UV-vis, and FTIR. Results show that Mn, N co-doped TiO₂/zeolite composites had higher activity than pristine TiO₂. The degradation rate of malachite green in the TiO₂ photocatalyst obtained under optimal doping conditions could reach 97% within 60 min in visible light, which was because the manganese ion doping could inhibit the recombination of TiO₂ photogenerated carriers and promote charge separation. Meanwhile, nitrogen doping could effectively broaden the photoresponse range of TiO₂. Moreover, after five usage cycles of Mn, N co-doped TiO₂/zeolite composites, the degradation rate of malachite green was not greatly reduced, maintaining above 88%, which indicates that the Mn, N co-doped TiO₂/zeolite composites have good photocatalytic cycle stability.