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

Graphical TiO 2 hollow sphere/UiO-66-NH 2 heterostructures were successfully synthesized by an adsorption-induced in-situ solvothermal growth strategy. The integration of TiO 2 and UiO-66-NH 2 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 TiO 2 /UiO-66-NH 2 . 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, TiO 2 hollow sphere/UiO-66-NH 2 (TiO 2 /UiO-66-NH 2 ) heterostructures were successfully synthesized by an adsorption-induced in-situ solvothermal growth strategy. The UiO-66-NH 2 particles were well dispersed on TiO 2 hollow spheres by solvothermal treatment of Zr 4+ adsorbed TiO 2 hollow spheres with NH 2 -BDC ligand. The photocatalytic activities of TiO 2 /UiO-66-NH 2 heterostructures were investigated by reduction of Cr(VI) with visible light irradiation. With the introduction of UiO-66-NH 2 , the reduction efficiency toward Cr(VI) by TiO 2 /UiO-66-NH 2 heterostructures reached 89% after 180 min of irradiation, which is much higher than those of TiO 2 hollow spheres (10%) and UiO-66-NH 2 crystals (29%). Moreover, the TiO 2 /UiO-66-NH 2 heterostructures display good regeneration ability and can still maintain 70% of Cr(VI) removal ability after four cycles. The integration of TiO 2 and UiO-66-NH 2 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.