Fig. 1 Ultrasonic spray aerosol process used to synthesize TiO2/SiO2 microspheres

Fig. 2 XRD patterns of the obtained TiO2/SiO2 MS and porous TiO2 MS after HF etching (the mass ratio of SiO2/TiO2 = 0.6, 20, 60 and 110 nm silica as the template)

Fig. 3 a XPS general spectrum, b Ti 2p spectrum, c O 1s spectrum of TiO2 MS before and after HF etching (the mass ratio of SiO2/TiO2 = 0.6, 20 nm silica as template)

Fig. 4 TEM and HRTEM images of the as-prepared porous TiO2 MS

Fig. 5 EDS and element mapping of TiO2 MS a before and b after the removal of the colloidal silica template

Fig. 6 SEM images of the as-prepared TiO2 MS before and after HF etching with different mass ratios of SiO2/TiO2: a, b 20%; c, d 60%; e, f 100% (a, c, e: before etching)

Fig. 7 SEM images of a pure TiO2 MS and b-d porous TiO2 MS made from different colloidal silica template diameters: b 20 nm; c 60 nm; d 110 nm

Fig. 8 a, b Nitrogen adsorption-desorption isotherm profiles; c, d pore distribution curves of pure TiO2 MS and porous TiO2 MS made from silica template according to colloidal silicate template diameters

Fig. 9 a UV light-induced photodegradation of MB in aqueous solutions using P25 and TiO2 MS made by 20 nm silica template with different contents; b the influence of silica template’s size on the photocatalytic performance of porous TiO2 MS for the degradation of MB (the mass ratio of SiO2/TiO2 is 60%); c the catalytic stability of TiO2 MS in 6 cycles; d UV-Vis absorption curves of porous TiO2 MS made from different sizes of silica template; e illustrated photoscattering and photocatalytic process under UV light irradiation; f the PL spectrum of solid TiO2 MS and porous TiO2 MS (20, 60 and 110 nm silica as the template)