Fabrication of Gold/Titania Photocatalyst for CO₂ Reduction Based on Pyrolytic Conversion of the Metal–Organic Framework NH₂‑MIL-125(Ti) Loaded with Gold Nanoparticles

Titania exhibits unique photophysical and -chemical properties and can be used for potential applications in the field of photocatalysis. The control of TiO₂ in terms of phase, shape, morphology, and especially nanoscale synthesis of TiO₂ particles still remains a challenge. Ti-containing metal–organic frameworks (MOFs), such as MIL-125, can be used as sacrificial precursors to obtain TiO₂ materials with diverse phase compositions, morphologies, sizes, and surface areas. MIL-125 is composed of Ti/O clusters as the secondary building units (SBUs) bridged by 1,4-benzenedicarboxylate (bdc). In this study, preformed and surfactant-stabilized gold nanoparticles (GNPs) were deposited onto the surface of amino functionalized NH₂-MIL-125 during solvothermal synthesis. Targeted gold/titania nanocomposites, GNP/TiO₂, were fabricated through the pyrolysis of GNP/NH₂-MIL-125 nanocrystals. The modification of TiO₂ with GNPs significantly increased the photocatalytic activity of the MOF derived TiO₂ material for the reduction of CO₂ to CH₄ as compared to TiO₂ reference samples such as P-25 and AUROlite (Au/TiO₂). The new materials GNP/TiO₂ and TiO₂ derived by the MOF precursor route were thoroughly characterized by PXRD, FTIR and Raman, TEM, and N₂ adsorption studies

Integration of Porous Coordination Polymers and Gold Nanorods into Core–Shell Mesoscopic Composites toward Light-Induced Molecular Release

Besides conventional approaches for regulating in-coming molecules for gas storage, separation, or molecular sensing, the control of molecular release from the pores is a prerequisite for extending the range of their application, such as drug delivery. Herein, we report the fabrication of a new porous coordination polymer (PCP)-based composite consisting of a gold nanorod (GNR) used as an optical switch and PCP crystals for controlled molecular release using light irradiation as an external trigger. The delicate core–shell structures of this new platform, composed of an individual GNR core and an aluminum-based PCP shell, were achieved by the selective deposition of an aluminum precursor onto the surface of GNR followed by the replication of the precursor into aluminum-based PCPs. The mesoscopic structure was characterized by electron microscopy, energy dispersive X-ray elemental mapping, and sorption experiments. Combination at the nanoscale of the high storage capacity of PCPs with the photothermal properties of GNRs resulted in the implementation of unique motion-induced molecular release, triggered by the highly efficient conversion of optical energy into heat that occurs when the GNRs are irradiated into their plasmon band. Temporal control of the molecular release was demonstrated with anthracene as a guest molecule and fluorescent probe by means of fluorescence spectroscopy