Synthesis of activated carbon-supported TiO₂-based nano-photocatalysts with well recycling for efficiently degrading high-concentration pollutants

It is highly desired to develop efficient TiO₂-based nano-photocatalysts with excellent recycling properties for practical application to degrade high-concentration pollutants. Herein, TiO₂ nanoparticles have been successfully modified by coupling activated carbon (AC), constructing heterojunction with SrTiO₃ and modifying with phosphoric acid. It is clearly demonstrated that the as-prepared nano-photocatalysts exhibit exceptional photoactivities for degrading high-concentration pollutants like 2,4-dichlorophenol (2,4-DCP) and bisphenol A (BPA), both with ∼3-time activity enhancement compared to commercial P25 TiO₂. Based on the surface photovoltage responses and the fluorescence spectra related to the formed ^[rad]OH amounts, it is deduced that the exceptional photocatalytic activities are attributed to the coupled AC for accepting electrons and promoting reactant adsorption, to the formed SrTiO₃ for inhibiting the anatase TiO₂ crystallite growth to increase the surface area and promoting the charge separation, and to the modified phosphate groups for promoting the adsorption of O₂ to enhance the charge separation. Furthermore, it is demonstrated through the radical trapping experiments that the photogenerated hydroxyl radicals could be dominant for the photocatalytic degradation of 2,4-DCP. This work would provide a feasible route to obviously enhance the photocatalytic activities of TiO₂-based nano-photocatalysts for the environmental remediation with good recycling properties.