Controllable Synthesis of MIL-101(Cr)@TiO2 Core-Shell Nanocomposites for Enhanced Photocatalytic Activity

Incorporating high surface area and high CO2 adsorptioncapacity of metal-organic frameworks (MOFs) together with highlyefficient semiconductor photocatalysts provides an ideal strategyfor designing CO2 reduction photocatalysts. Controllablegrowth of TiO2 nanoparticles on MIL-101(Cr) can be obtainedand yields MIL-101(Cr)@TiO2 core-shell photocatalystsvia a fluoride-assisted solvothermal method. Corrosion occurs on thesurface of MIL-101(Cr) by the action of F- and generatesan activated surface, facilitating the growth of a TiO2 shell. MIL-101(Cr)@TiO2 nanocomposites with differentTiO(2) contents are remarkably fabricated by controllingthe reaction conditions. The morphology, structure, surface area,and composition of the as-prepared MIL-101(Cr)@TiO2 nanocompositesare investigated by various characterization methods. The EDS mappingimages reveal that the Ti and O elements are uniformly distributedon the shell, but Cr and C elements are mainly situated at the coreof the composite, which further indicates the successful synthesisof the MIL-101(Cr)@TiO2 core-shell structure. Thephotocatalytic conversion of CO2 into CH4 isnoticeably enhanced by the produced MIL-101(Cr)@TiO2 octahedrainheriting both large surface area (387.3 m(2) g(-1)) and high CO2 adsorption capacity. Compared to pure TiO2 nanoparticles under the same conditions, the optimized MIL-101(Cr)@TiO2 photocatalyst exhibits a much greater CO2 conversionefficiency, with a CH4 generation rate of 0.22 & mu;molh(-1) g(-1). This work will advancethe experimental and theoretical basis for exploring highly efficientCO(2) reduction photocatalysts.