不同种类金属掺杂改性TiO2材料光催化性能的研究进展

Research Progress in Improving the Photocatalytic Properties of TiO2 Materials by Doping with Different Metals

半导体光催化剂因可以直接利用太阳光进行光催化且不产生二次污染,成为一种应用于环境污染治理领域较为理想的材料。其中TiO2光催化剂具有较高的光稳定性、良好的化学性质、无毒、较低的成本、高的光催化效率等特点,目前受到广泛的研究与关注。然而,TiO2快速复合的电子-空穴及较大的禁带宽度等自身缺陷,导致其量子产率不高,TiO2中的电子只能在紫外光下被激发,这些因素使得它的光催化性能受到了制约。因此,近年来通过研究不同的金属元素掺杂TiO2基光催化剂及研究不同特殊微纳结构来克服TiO2自身缺陷以改善其光催化性能并取得较大的进展。研究发现,通过将不同金属(如Ag、Fe、Cu、Ce等)以一元、二元、多元的形式掺入TiO2中,可改善TiO2的自身缺陷,并在催化剂表面产生不同作用,使其光响应范围增大,光催化性能显著提升。此外,研究者们还发现,特殊微纳结构的存在可以加快金属掺杂TiO2基光催化材料的电子转移,从而提高TiO2光生电子-空穴的分离效率,增加了其量子产率。金属掺杂后,TiO2对有机物的降解率及其产氢能力、光能转化率都得到了显著的提高,使其不仅在紫外光下具有优异的性能,而且在可见光下也能进行良好的光催化。掺杂后TiO2的抗菌效果与防雾性能也得到了显著的提升。本文一方面综述了不同金属掺杂体系(一元、二元复合以及多元复合掺杂)对TiO2结构及其光催化性能的改变,总结不同制备工艺对TiO2结构与性能的影响规律,并分析光催化性能的增强机制。另一方面概述了金属掺杂TiO2基复合材料的一些特殊微纳结构包括石墨烯包覆结构、核-壳结构以及其他结构的制备工艺,并讨论了不同微纳结构与金属掺杂在增强TiO2光催化性能上所起的作用。最后简单综述了不同金属掺杂TiO2纳米复合材料的不同应用,展望了未来研究方向及应用领域。

The semiconductor photocatalyst is an ideal material for environmental pollution treatment because it can directly use solar light for photocata-lysis without secondary pollution.Among them,TiO2 photocatalyst has been widely studied and paid attention to because of its high light stability,good chemical properties,non-toxicity,low cost and high photocatalytic efficiency.However,the rapid recombination of electron-holes of TiO2 leads to a lower quantum yield,which limits its photocatalytic performance.Moreover,because of the large forbidden band width of TiO2 photocatalyst,its electrons can only be excited under ultraviolet light,and the utilization rate of solar energy is relatively low,which limits its application under visible light.Therefore,in recent years,the photocatalytic performance has been improved by studying the doping of TiO2 with different metal elements and the metal doped TiO2-based photocatalyst with special micro/nano structure,and has made great progress.It is found that the doping of metal elements reduces the recombination rate of TiO2 electron-holes,narrows the forbidden band width of TiO2,and increases the photoresponse range,thereby enhancing the photocatalytic performance and expanding its application prospect under visible light.In addition,the researchers found that the existence of special micro-nanostructures can accelerate the electron transfer of metal-doped TiO2-based composites,thus increasing the separation efficiency of TiO2 photogenerated electron-holes and increasing their quantum yield.After metal doping,TiO2 has significantly improved the degradation rate of organic matter,hydrogen production capacity and light energy conversion rate,and its antibacterial effect and anti-fog performance have also been significantly improved.On the one hand,this paper reviews the changes of TiO2 structure and photocatalytic properties of different metal doping systems including single element,binary composite and multi-component doping.The effects of different preparation processes on structure and properties are summarized,and the enhancement mechanism of photocatalytic performance is analyzed.On the other hand,preparation processes on some special micro-nano structures of metal-doped TiO2-based composites,including graphene cladding structure,core-shell structure and other structures,are discussed.Different micro-nano structures and metal doping for enhanced photocatalysis are discussed.Finally,the different applications of different metal doped TiO2 nanocomposites are briefly reviewed,and the future research directions and application fields are prospected.