Controllable preparation and photocatalytic performance of hollow hierarchical porous TiO2/Ag composite microspheres

Mesoporous titania-based composites have attracted much attention in the world due to their large specific surface area, high material transport efficiency, and photocatalytic efficiency. The hollow and hierarchical porous structure is rarely involved in a binary photocatalytic material. In the present work, a novel type of hollow hierarchical porous TiO2/Ag composite microsphere with tunable microstructure was successfully prepared by simple solution methods, including sol-gel method, template method and impregnation method. Hollow hierarchical porous TiO2 microspheres were prepared by a sol-gel process with P123 as a hierarchical pore structure guide agent and template method with polystyrene microspheres as a hollow hard template. Further, hollow hierarchical porous TiO2/Ag composite microspheres were obtained by modifying Ag in the hollow hierarchical porous TiO2 microspheres by the impregnation method. The different hollow hierarchical porous TiO2/Ag composite microspheres are obtained by changing the molar ratio R of Ti/Ag. The optimal addition amount of Ti and Ag in sample HHPA6 (10:0.5) is the molar ratio of 10:0.5, and the experimental value of XPS is the molar ratio of 10:0. 91. Compared with the hollow hierarchical porous TiO2 microspheres, the excitation wavelength of composite microspheres is shifted to the visible light direction by 24 nm, and their response range and their light utilization rate were improved. When the molar ratio R of Ti/Ag is 10:0.5, hollow hierarchical porous TiO2/Ag composite microspheres have a specific surface area of 177 m2/g, the pore volume of 0.37 cm3/g, and the primary and secondary pore size of 4.04 nm and 7.74 nm, respectively. It shows the highest photocatalytic activity in the ultraviolet band of 365 nm and 395 nm, and the degradation rate of methyl orange solution is 96.84% and 98.65%, respectively. Their excellent photocatalytic performance is attributed to their special structure combining hierarchical pores and hollow structures as well as the synergistic effect of Ag and TiO2.