微观形貌可控TiO_2的制备及其光解水产氢性能

Synthesis and Photochemical Performances of Morphology-Controlled TiO_2 Photocatalysts for Hydrogen Evolution under Visible Light

通过简单的沉淀、水热、溶剂热和溶胶凝胶法分别制备出实心球(s-TiO_2)、空心球(h-TiO_2)、纳米管(a-TNT)和介孔形状(mTiO_2)的锐钛矿晶型结构TiO_2光催化材料。采用HRTEM、FESEM、XRD、UV-Vis、N2吸-脱附和光解水制氢反应等对催化材料的微观表面结构、光吸收性能以及不同形貌光催化剂的光解水制氢的性能对比研究。结果表明:s-TiO_2具有最高的光催化活性,主要归功于s-TiO_2独特的微观形貌结构所致,s-TiO_2是由亚微晶颗粒组成的介孔状实心球,亚微晶粒径相比较其它形貌的材料要小,有利于光生载流子的迁移,抑制电子-空穴对的体相复合,导致活性提高。同时,晶化过程用于传质通道的无序微孔可以束缚用作牺牲剂的CH3OH分子,使得空穴快速被牺牲剂消耗,减少与电子复合。

TiO2 solid spheres （s-TiO2）, hollow spheres （h-TiO2）, nanotubes （a-TNT） and mesoporous TiO2 （m-TiO2） were morphology-controlled constructed via facile solution synthesis and solvent thermal methods. The different surface properties and electronic structures were characterized by HRTEM, FESEM, XRD, UV-Vis and N2 absorption-desorption measurements. The photocatalytic performance was evaluated by H2 evolution, which showed morphology-different photocatalytic activities. Among these TiO2 photocatalysts, s-TiO2 gave the best performance in the photocatalytic activity, which might be attributed to its special mesoporous solid spheres constructed by tiny well-crystallized TiO2 nanocrystals. The basic building blocks in the mesoporous solid spheres facilitated the transport of photo-excited carrier, and restricted the recombination of electron-hole pair, which enhanced the photocatalytic activity. Furthermore, the mesoporous structure of s-TiO2 showed the advantage in combining the methanol, a sacrificed agent, which easily consume the photo-excited holes and restrict the recombination of holes with photo-excited electrons.