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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.

In this study, we present the positive effect of 1,10phenanthroline as an electrolyte additive that is strongly adsorbed on activated carbon electrodes, thereby adding effective redox activity to their initially capacitive interactions with electrolyte solutions. We obtain a stable capacitance of 320 F/g for the negative electrode and 190 F/ g electrode for full symmetric supercapacitor cells, operating up to 3.4 V in nonaqueous media, during many thousands of cycles. This corresponds to a specific capacity of 180 (mA h)/g electrode . The high voltage and capacity of these systems can pave the way for developing high-energy-density pseudocapacitors that may be able to compete with battery systems. We explored the mechanisms of the electrode interactions using electrochemical tools, including impedance spectroscopy.

The main goal of this work was to modify activated carbon (AC) with carbon nanodots (C-dots) and to explore the modified composites as electrode materials for supercapacitors. C-dots were synthesized by sonication of polyethylene glycol followed by sonochemical modification of AC matrices with the preprepared C-dots. Sonication introduces the C-dots into the pores of the AC. The effect of the introduction of the C-dots into the AC and their incorporation into the pores was studied. The porosity of the AC/C-dots and the AC reference materials was explored, as well as the impact of the C-dot loading on the performance of the electrodes comprising these AC/C-dots. It was found that the AC/C-dot electrodes demonstrate a specific capacitance of 0.185 F/cm2 (per specific electrode area), three times higher than the capacitance of unmodified AC electrodes per specific electrode’s area. It was established that the new electrode’s material, namely, AC/C-dots, exhibits very stable electrochemical behavior. Many thousands of cycles could be demonstrated with stable capacity and a Coulombic efficiency of around 100%.

We report fabrication of flexible all-solid-state transparent electrochromic patterned microsupercapacitors based on twodimensional layered nanostructured molybdenum oxide (MoO 3−x )/ poly(3,4-ethylenedioxythiophene)−polystyrenesulfonate (PE-DOT:PSS) nanocomposite electrodes. Exceptional electrochemical performance of the transparent microsupercapacitors includes fast kinetics and response times, high specific capacitances (up to 79.2 C/ g, 99 F/g, and 2.99 mF/cm 2 ), and Coulombic efficiencies of 99.7% over 2500 cycles. Such exceptional performance is attributed to the synergistic effects of PEDOT:PSS providing high electrical conductivity and high charge storage capacity along with its segregated interfacial nanostructure facilitating the intercalation of the ionic species, H + (Na + , K + ) and SO 4 2− , into the high surface area tunnel structure of the 2D MoO 3−x nanosheets. Supercapacitors using MoO 3−x PEDOT:PSS electrodes exhibit optical transmittance above 70% (λ = 380−730 nm). The electrochromic performance of the transparent microsupercapacitor is due to both PEDOT:PSS and cation (H + ) intercalation in the tunnel structure of MoO 3−x .