Preparation And Photocatalytic Activity Of Hollow Spheres And Their Complexes With High Thermal Stabilized Mesoporous TiO 2

Mesoporous TiO₂ hollow spheres have recently attracted increasing research interests because of their specific features, such as low density, high surface-to-volume ratio, the effect of void space, high shell permeability, excellent electronic and optical properties, and widespread applications in fields of photocatalysis, solar cells, photoelectrochemical water splitting, drug delivery, and energy storage. Usually, the synthesis approach includes templating and template-free methods. The template-based synthesis benefits for great versatility for various hollow structures, but creating uniform coatings on the corresponding templates and removing them is quite complicated. Moreover, the large bandgap of anatase TiO₂（ 3.2 eV） greatly limits the efficiency of solar-driven photocatalysis, because the light absorption is only confined in ultraviolet（UV） region, which represents a small fraction of solar energy.In this paper, we demonstrate a facile route to synthesize stable mesoporous black TiO₂ hollow spheres with controllable diameters and wall thicknesses through template-free solvothermal approach combined with small amine molecules encircling strategy and atmospheric hydrogenation. Our synthesis system is suitable for efficient encircling of these small amine molecules on the surface of the mesoporous TiO₂ hollow spheres, in which the hollow structures and anatase phase can be maintained up to 900 °C. The highly-thermostable mesoporous TiO₂ hollow spheres are good candidate for subsequent high-temperature hydrogenation. The obtained mesoporous black TiO₂ hollow spheres possess a relative high surface area of 80 m2 g-1, and a large pore size of 12 nm. The diameters and wall thicknesses are controlled from 500 nm to 1 mm and 35 to 115 nm, respectively. Moreover, the MBTHS extends the photoresponse from UV to visible light region and exhibits a high solar-driven photocatalytic hydrogen evolution rate（241 μmol h-1 0.1 g-1）.The stable mesoporous black TiO₂ hollow spheres will be an excellent host. Herein,we prepared mesoporous black TiO₂-Ag hollow spheres by vacuum induction assisted method and tested the photocatalytic performance. Silver particles with mesoporous black TiO₂ hollow spheres constructs an electronic transfer channel for effective separation of photogenerated electrons and holes, and greatly improve the photocatalytic activity of mesoporous black TiO₂-Ag hollow spheres under visible light and AM 1.5 irradiation（339 μmol h-1 0.1 g-1）.