Macroporous-mesoporous C-, S-, N-doped titania microspheres via the polyHIPE microspheres templates

Doping and increasing specific surface area by forming highly porous structures are two effective ways to enhance the photocatalytic performances of TiO2 particles. Here for the first time, we report a new facile method to prepare the macroporous-mesoporous C-, S-, N-doped TiO2 (C/S/N-TiO2) microspheres via polyHIPE microspheres as templates. The chemical and crystalline structures of these hierarchical porous TiO2 microspheres are analyzed with FTIR, XPS, EDS, and XRD. The macroporous-mesoporous structures are confirmed with SEM observation and BET analysis. UV–vis DRS spectra analysis shows that the band gaps of C doped TiO2, C/N doped TiO2, C/S doped TiO2 and C/S/N doped TiO2 are estimated to be 3.07, 3.01, 2.94 and 2.81 eV, respectively, which are significantly narrower than that of TiO2 nanoparticles (3.23 eV). Photoluminescence spectra demonstrate that the recombination of electrons and holes in these macroporous-mesoporous TiO2 microspheres is also suppressed. The hierarchical porous C/S/N-TiO2 microspheres show high visible-light catalytic efficiency and excellent cycling stability to degrade RhB dye.