Fabrication of bimodal-pore SrTiO3 microspheres with excellent photocatalytic performance for Cr(VI) reduction under simulated sunlight.

Solving the increasing contamination from toxic heavy metal ions in wastewater is an imperative issue in photocatalysis research area. In this study, three-dimensional (3D) porous SrTiO 3 microspheres have been fabricated by a sol–gel-templating method using the agarose gel bead containing SrCO 3 granules as the template. The resultant SrTiO 3 microspheres, several tens of micrometers in diameter, exhibit a bimodal pore structure, in which the macropore about 70–150 nm in size stems from SrCO 3 granules and the mesopore about 3 nm is formed via removing the agarose fiber embedded in the composite microspheres. The porous framework of SrTiO 3 microspheres is assembled by regular single-crystalline SrTiO 3 nanocubes with an edge length of 100 ± 10 nm. The highly interconnected porous network renders numerous pathways for the rapid mass transport, strong adsorption of reactants and multi-reflection of incident light. Moreover, the as-prepared SrTiO 3 microspheres exhibit excellent photocatalytic performance for the Cr(VI) reduction under simulated sunlight, which can reduce nearly 100% Cr(VI) at pH 2 within 2 h and retain a relatively high reduction ability after six recycles. [ABSTRACT FROM AUTHOR]