Adsorption‐Induced In‐Situ Construction of TiO2 Hollow Sphere/UiO‐66‐NH2 Heterostructures with Boosted Photocatalytic Activity toward Cr(VI) Reduction

TiO₂ hollow sphere/UiO-66-NH₂ heterostructures were successfully synthesized by an adsorption-induced in-situ solvothermal growth strategy. The integration of TiO₂ and UiO-66-NH₂ could construct a type-II heterojunction to broaden the absorption range of light and suppress the recombination of photoproduced electrons and holes, thus boosting the photoreduction activity toward Cr(VI) of TiO₂/UiO-66-NH₂.

Abstract

Water contamination caused by highly toxic Cr(VI) should be resolved imminently with a more efficient photocatalytic approach. The interaction between photocatalyst heterostructure is critical for charge separation which largely affects the photocatalytic efficiency. Herein, TiO₂ hollow sphere/UiO-66-NH₂ (TiO₂/UiO-66-NH₂) heterostructures were successfully synthesized by an adsorption-induced in-situ solvothermal growth strategy. The UiO-66-NH₂ particles were well dispersed on TiO₂ hollow spheres by solvothermal treatment of Zr⁴⁺ adsorbed TiO₂ hollow spheres with NH₂-BDC ligand. The photocatalytic activities of TiO₂/UiO-66-NH₂ heterostructures were investigated by reduction of Cr(VI) with visible light irradiation. With the introduction of UiO-66-NH₂, the reduction efficiency toward Cr(VI) by TiO₂/UiO-66-NH₂ heterostructures reached 89% after 180 min of irradiation, which is much higher than those of TiO₂ hollow spheres (10%) and UiO-66-NH₂ crystals (29%). Moreover, the TiO₂/UiO-66-NH₂ heterostructures display good regeneration ability and can still maintain 70% of Cr(VI) removal ability after four cycles. The integration of TiO₂ and UiO-66-NH₂ could construct a type-II heterojunction to broaden the absorption range of light and suppress the recombination of photoproduced electrons and holes. As a result, such unique composite structure significantly enhance the photocatalytic performance towards Cr(VI) reduction. This work not only inspires a new approach for in-situ solvothermal synthesis of semiconductor@MOFs composites, but provides a novel photocatalyst for highly efficient removal of Cr(VI) from wastewater.

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