Enhanced photocatalytic properties of MWCNTs-decorated SrTiO3-SrCO3 hierarchical structures achieved by efficient charge transfer

Cr (VI) is a heavy metal ion that cannot be ignored in industrial wastewater and is highly toxic, posing a serious threat to the health and safety of natural organisms. In order to remove Cr (VI) ions in the wastewater, photocatalysis is currently employed and becomes a promising and effective way but the photocatalytic rate still needs further improvement. In this work, multi-walled carbon nanotubes (MWCNTs) modified SrTiO3-SrCO3 microspheres with a three-dimensional porous structure were prepared by a facile solvothermal method. When the dosage of MWCNTs was 0.55 wt%, the obtained sample exhibited the highest photocatalytic efficiency, with approximately 100 % removal of Cr (VI) within 6 min and the photocatalytic rate constant (k) can reach 0.52 min -1 under full-spectrum light irradiation. The enhancement in the photocatalytic performance is probably attributed to the large surface area for more adsorption of Cr (VI) ions on the sample and effectively transfer of photo-generated carriers via the hetero-structures for the reaction of Cr (VI) ions with more carriers. Therefore, this work can provide a facile method for the preparation of photocatalysts with good performance for the removal of Cr (VI) in the wastewater.