Metal organic frameworks (MOFs) have unique properties that make them excellent candidates for many high-tech applications. Nevertheless, their nonconducting character is an obstacle to their practical utilization in electronic and energy systems. Using the familiar HKUST-1 MOF as a model, we present a new method of imparting electrical conductivity to otherwise nonconducting MOFs by preparing MOF nanoparticles within the conducting matrix of mesoporous activated carbon (AC). This composite material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption measurements, and electron paramagnetic resonance (EPR) spectroscopy. We show that MOF nanoparticles grown within the carbon matrix maintain their crystalline characteristics and their surface area. Surprisingly, as a result of the composition process, EPR measurements revealed a copper signal that had not yet been achieved. For the first time, we could analyze the complex EPR response of HKUST-1. We demonstrate the high conductivity of the MOF composite and discuss various factors that are responsible for these results. Finally, we present an optional application for using the conductive MOF composite as a high-performance electrode for pseudocapacitors.
Micro-patterning of a metal organic framework (MOF) from a solution of precursors is achieved by local laser heating, alleviating the need for pre-preparation and stabilization.
Silver is known as a viable alternative for platinum group metals for the catalysis of the oxygen reduction reaction in alkaline electrolyte. Unlike most other platinum-group metal-free catalysts, usually organo-metallic complexes, silver is commonly used in its metallic form (Ag(0)). Herein, we describe the preparation, characterization, and electrochemical activity of a unique silver-based catalyst, based on Ag(I) ions coordinated to oxygen groups in an organic ligand (benzene tricarboxylic acid -BTC) which forms a metal organic framework, similar to first-row transition metal-based catalysts in metal organic frameworks. When the silver-based catalyst is incorporated in a porous carbon support, it exhibits high electrocatalytic activity for the oxygen reduction reaction, with a distinct electrochemical behavior, different than metallic silver. In addition, the use of the ionic form of the silver, which is atomically dispersed, allows to lower its loading of the metal by at least one order of magnitude when compared to other reported silver-based oxygen reduction reaction catalysts.
Results and DiscussionAg-BTC and Ag-BTC@AC were synthesized according to the procedure described in the experimental section. Two-probes bulk conductivity measurements showed that the AgBTC is practically an insulator, as many other metal-BTC, [5,8] unlike the high electronic conductivity of metallic silver. Therefore, AgBTC cannot be utilized as a stand-alone electrocatalyst/electrode in [a] S.
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