A new Cu nanoparticles embedded porous carbon composite was prepared by simple pyrolysis of HKUST-1, which shows high efficient (detection limit: 3.2 × 10−9 M) glucose sensing ability with high selectivity.
To date, numerous materials, including various quantum dots and dyes, have been widely used for the ultrasensitive detection of toxic metal ions and as security inks to hide information. Nevertheless, because of the poor dispersibility of solid-state materials, security inks based on such materials have been scarcely reported. Herein, a highly dispersible and water-stable metal−organic framework (MOF; NH 2 -MIL-125(Ti)) is used as an invisible security ink for data coding, encryption, and decryption via its "turn-on/off" switching by treatment with ethylenediaminetetraacetic acid and Pb 2+ . Notably, the concentration of the Pb 2+ solution used to turn off the fluorescence of the MOF was lower than the limit established by several regulatory agencies for drinking water. The MOF was also used as a sensitive probe for the rapid and ultrasensitive detection of Pb 2+ ions at a concentration of 7.7 pM which is one of the lowest detection limits reported for such a system. The MOF also shows high selectivity for various transition metal ions that can competitively bound on the ligand. Analyses using Fourier transform infrared spectroscopy,X-ray photoelectron, and UV photoemission spectroscopy clearly revealed the roles of the surface functional groups and the mechanism of the "on/off" switching behavior of the MOF.
Recently, metal nanoparticles embedded in porous carbon composite materials have been playing a significant role in a variety of fields as catalyst supports, sensors, absorbents, and in energy storage. Porous carbon composite materials can be prepared using various synthetic methods; recent efforts provide a facile way to prepare the composites from metal-organic frameworks (MOFs) by pyrolysis. However, it is usually difficult to control the phase of metal or metal oxides during the synthetic process. Among many types of MOF, recently, cobalt-based MOFs have attracted attention due to their unique catalytic and magnetic properties. Herein, we report the synthesis of a Pt doped cobalt based MOF, which is subsequently converted into cobalt nanoparticle-embedded porous carbon composites (Pt@Co/C) via pyrolysis. Interestingly, the phase of the cobalt metal nanoparticles (face centered cubic (FCC) or hexagonal closest packing (HCP)) can be controlled by tuning the synthetic conditions, including the temperature, duration time, and dosage of the reducing agent (NaBH4). The Pt doped Co/C was characterized using various techniques including PXRD (powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), gas sorption analysis, TEM (transmission electron microscopy), and SEM (scanning electron microscopy). The composite was applied as a phase transfer catalyst (PTC). The Fischer-Tropsch catalytic activity of the Pt@Co/C (10:1:2.4) composite shows 35% CO conversion under a very low pressure of syngas (1 MPa). This is one of the best reported conversion rates at low pressure. The 35% CO conversion leads to the generation of various hydrocarbons (C1, C2–C4, C5, and waxes). This catalyst may also prove useful for energy and environmental applications.
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