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 TiO 2 –ZrO 2 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 N 2 adsorption–desorption measurements are employed to characterize the composition, structure, and morphology of TiO 2 –ZrO 2 hollow spheres. The results show that TiO 2 –ZrO 2 hollow spheres are mainly TiO 2 anatase and retain well the spherical structure of the PS crystal template, whose shell is closely packed by TiO 2 –ZrO 2 nanoparticles, with thickness of ca. 24 nm. The combination of TiO 2 and ZrO 2 and the special hollow structure are beneficial to improve the photocatalytic activity. TiO 2 –ZrO 2 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 H 2 evolution quantity in 8 h, which is produced by the photolysis of water, is 23.7 μmol, indicating that TiO 2 –ZrO 2 hollow spheres have a certain hydrogen production performance. Moreover, the results of the trapping experiment indicate that the active radicals • O 2 –, h +, and • OH – are responsible for the photocatalytic reaction, and the possible reaction mechanism of TiO 2 –ZrO 2 hollow spheres in both photocatalytic degradation and photocatalytic H 2 evolution from splitting water is also proposed.