Enhanced photocatalytic properties of mesoporous heterostructured SrCO3-SrTiO3 microspheres via effective charge transfer

Photocatalytic reduction is currently one of the most promising methods for the removal of heavy metal hexavalent chromium ions from aqueous environments, for which increasing focus has been directed towards heterostructure engineering of the existing photocatalysts, like SrTiO3. In this work, mesoporous heterostructured SrCO3-SrTiO3 microspheres constructed from nanosheets were synthesized by a facile one-step solvothermal method using ethylene glycol (EG) and water as mixed solvents and exhibited enhanced photocatalytic performance in the degradation of 99.78% for the reduction of Cr(VI) under UV irradiation for 3 min compared with pure SrTiO3 microspheres, which is better than that of most photocatalysts in the previous works. The enhancement in the photocatalytic performance was probably attributed to the formed heterostructures between SrCO3 and SrTiO3 grains which can facilitate the transfer of photo-induced electrons from the conduction band (CB) of SrTiO3 to CB of SrCO3, and adsorbed EG molecules which can consume the holes in valence band (VB) of SrTO3, thus reducing the recombination of photo-induced carriers. In addition, the mesoporous structures with a large surface area can provide more active sites for the adsorption of Cr(VI) and thus accelerate subsequent reduction reaction of Cr(VI) with photo-induced electrons. Therefore, this work can provide a facile way to prepare high-performance photocatalysts for highly efficient and low-cost removal of Cr(VI).