Developing cheap photocatalysts with highly visible-light activity is greatly desired for environmental pollution treatment. In this work, the authors designed and synthesised Cu 2+ -doped TiO 2 (Cu-TiO 2 ) hollow spheres with enhanced photocatalytic activity and antimicrobial activity using a simple hydrothermal process. The X-ray powder diffraction (XRD) results revealed that Cu-TiO 2 hollow spheres were anatase crystal phase. The Cu 2+ -doped into TiO 2 can be confirmed by XRD, Raman spectra, and UV–Vis spectrum. The photocatalytic activity of Cu-TiO 2 samples was evaluated by the degradation of methyl orange. Comparing to the undoped TiO 2 , 6% Cu-TiO 2 sample exhibited remarkably high photocatalytic towards methyl orange under simulated sunlight irradiation, which was attributed to the fact that copper ion doping produced numerous oxygen vacancies (V O ) in the material. In addition, it also showed improved antibacterial properties against both Gram-positive Staphylococcus aureus ( S.aureus ) and Gram-negative Escherichia coli ( E.coli ) bacteria. These results establish that Cu 2+ doping can obviously improve the photocatalytic performance of TiO 2 under simulated sunlight.
Liping Ren,Wei Zhou,Bojing Sun,Haoze Li,Panzhe Qiao,Yachao Xu,Jiaxing Wu,Kuo Lin,Honggang Fu
Defect-engineered magnetic γ-Fe 2 O 3 ultrathin nanosheets/mesoporous black TiO 2 hollow sphere heterojunctions (γ-Fe 2 O 3 /b-TiO 2 ) are fabricated by a metal-ion intervened hydrothermal technique and high-temperature hydrogenation, which exhibit wide-spectrum response and magnetic separation. The specific surface area, pore size and pore volume of the resultant γ-Fe 2 O 3 /b-TiO 2 with hollow structure are ∼63 m 2 g −1 , 10.5 nm and 0.14 cm 3 g −1 , respectively. After surface hydrogenation, α-Fe 2 O 3 nanosheets are converted to γ-Fe 2 O 3 ultrathin nanosheets (∼6 nm) combined with the formation of surface defects. The ultrathin nanosheet structure facilitates the surface engineering and also favors the diffusion and transportation of photogenerated charge carriers. The apparent rate constant (k) of defect-engineered γ-Fe 2 O 3 /b-TiO 2 photocatalytic degradation biotoxic tetracycline is ∼3 times higher than that of α-Fe 2 O 3 /b-TiO 2 under AM 1.5 irradiation. The enhancement is attributed to the introduction of narrow bandgap unit-cell-thick γ-Fe 2 O 3 nanosheets, the hollow structure and the defect engineering, which are beneficial to solar-light-harvesting and rapid electron transport, and spatial separation of photogenerated charge carriers. The photocatalytic degradation mechanism is also proposed. The novel magnetic γ-Fe 2 O 3 /b-TiO 2 heterojunction is a promising photocatalyst for recovering the domestic sewage in environment.
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.
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