Novel copper-doped manganese ferrite nanoparticles were synthesized using a low-cost facile route via. hydrothermal method which provided high surface area and good conductivity for use as functional materials for storing and producing energy. A "hybrid mix" of the nano-ferrites with polyaniline showed a phenomenal influence on the investigated electrochemical properties. The hybrid mix gave maximum specific capacitance of 478.797 mAh/g of the symmetrical supercapacitor at 1 A/g current density and displayed an excellent cycling stability with capacitance retention of 78% after 5000 cycles. Morphology and structural analysis was carried out using Transmission electron microscope, Field-emission scanning electron microscope, and Fourier transform infra-red spectroscopy in detail. The interactive mechanism between the Cu x Mn (1-x) Fe 2 O 4 and PANI in the Cu x Mn (1-x) Fe 2 O 4 @PANI hybrid electrode material was investigated using RAMAN and X-ray photoelectron microscopy. In addition, the proposed energy storage system has been constructed without using any binder which simplified the electrode fabrication process by preventing the contact resistance between the electrode and current collector.
Porphyrins have multiple roles in living and nonliving systems because of their exceptional tunable chemical and physical properties. They are interesting macrocyclic compounds that could be modified in a number of ways. The structural diversity of porphyrinoids make them a unique choice for functional devices exhibiting photo‐ and electrochemical properties. Their properties can be modified or altered by either protonating the nitrogen atoms or by inducing charge transfer to the metal center. Structural changes induced by flattening and planar distortions, redox reactions, solvents, and porphyrin aggregations also influence the photo‐ and electro‐chemical properties of porphyrinoids. This review gives a brief explanation on the effects of structural orientation, molecular structure, and charge on the properties of porphyrinoids. The review also illustrates the correlation between the geometrical features and the photo‐ and electrochemical behavior of porphyrinoids.
Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving their performance. To this end, a conventional mathematical and a physicochemical model were adapted. The impedance was measured by electrochemical impedance spectroscopy (EIS). An EC consisting of electrical elements was introduced for each modeling approach. The mathematical model was purely based on a best-fit method and utilized an EC with intuitive elements. In contrast, the physicochemical model was motivated by advanced theories and allowed meaningful associations with properties at the electrode, the electrolyte, and their interface. The physicochemical model showed a higher approximation ability (relative error of 3.7%) due to the interface impedance integration in a more complex circuit design. However, this model required more modeling and optimization effort. Moreover, the fitted parameters differed from the analytically calculated ones due to uncertainties in the SSC’s microscale configuration, which need further investigations. Nevertheless, the results show that the proposed physicochemical model is promising in simulating EIS data of SSCs with the additional advantage of utilizing well-reasoned property-based EC elements.
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