MIL-125-NH2@TiO2 Core–Shell Particles Produced by a Post-Solvothermal Route for High-Performance Photocatalytic H2 Production

Metal–organic frameworks (MOFs) have proven to be an interesting class of sacrificial precursors of functional inorganic materials for catalysis, energy storage, and conversion applications. However, the controlled synthesis of MOF-derived materials with desirable compositions, structures, and properties still remains a big challenge. Herein, we propose a post-solvothermal route for the outer-to-inner loss of organic linkers from MOF, which is simple, rapid, and controllable and can be operated at temperature much lower than that of the commonly adopted pyrolysis method. By such a strategy, the MIL-125-NH2 particles coated by TiO2 nanosheets were produced, and the thickness of TiO2 shell can be easily tuned. The MIL-125-NH2@TiO2 core–shell particles combine the advantages of highly active TiO2 nanosheets, MIL-125-NH2 photosensitizer, plenty of linker defects and oxygen vacancies, and mesoporous structure, which allows them to be utilized as photocatalysts for the visible-light-driven hydrogen production reaction. It is remarkable that the hydrogen evolution rate by MIL-125-NH2@TiO2 can be enhanced 70 times compared with the pristine MIL-125-NH2. Such a route can be easily applied to the synthesis of different kinds of MOF-derived functional materials.