Hollow Sphere TiO2–ZrO2 Prepared by Self-Assembly with Polystyrene Colloidal Template for Both Photocatalytic Degradation and H2 Evolution from Water Splitting

On the basis of a self-assembly technique with polystyrene (PS) spheres as colloidal template, the composite TiO2–ZrO2 hollow spheres are synthesized by combining a water bath with a calcining postprocessing method. XRD, UV–vis/DRS, XPS, SEM–EDS, TEM, HR-TEM, and N2 adsorption–desorption measurements are employed to characterize the composition, structure, and morphology of TiO2–ZrO2 hollow spheres. The results show that TiO2–ZrO2 hollow spheres are mainly TiO2 anatase and retain well the spherical structure of the PS crystal template, whose shell is closely packed by TiO2–ZrO2 nanoparticles, with thickness of ca. 24 nm. The combination of TiO2 and ZrO2 and the special hollow structure are beneficial to improve the photocatalytic activity. TiO2–ZrO2 hollow spheres have remarkable photocatalytic properties under UV light, simulated sunlight, and microwave-assisted three different modes, which can also degrade organic pollutants of different structures. In addition, the H2 evolution quantity in 8 h, which is produced by the photolysis of water, is 23.7 μmol, indicating that TiO2–ZrO2 hollow spheres have a certain hydrogen production performance. Moreover, the results of the trapping experiment indicate that the active radicals •O2–, h+, and •OH– are responsible for the photocatalytic reaction, and the possible reaction mechanism of TiO2–ZrO2 hollow spheres in both photocatalytic degradation and photocatalytic H2 evolution from splitting water is also proposed.