A redox conducting polymer of a meso-Ni(II)-SaldMe monomer and its application for a multi-composite supercapacitor

Bridging the Gap between Charge Storage Site and Transportation Pathway in Molecular-Cage-Based Flexible Electrodes

Porous materials have been widely applied for supercapacitors; however, the relationship between the electrochemical behaviors and the spatial structures has rarely been discussed before. Herein, we report a series of porous coordination cage (PCC) flexible supercapacitors with tunable three-dimensional (3D) cavities and redox centers. PCCs exhibit excellent capacitor performances with a superior molecular capacitance of 2510 F mmol^-1, high areal capacitances of 250 mF cm^-2, and unique cycle stability. The electrochemical behavior of PCCs is dictated by the size, type, and open-close state of the cavities. Both the charge binding site and the charge transportation pathway are unambiguously elucidated for PCC supercapacitors. These findings provide central theoretical support for the "structure-property relationship" for designing powerful electrode materials for flexible energy storage devices.

Ni(OH)2-Type Nanoparticles Derived from Ni Salen Polymers: Structural Design toward Functional Materials for Improved Electrocatalytic Performance

Herein, we report the potential-driven electrochemical transformation carried out in basic media of two Ni2+ salen polymers, (poly(NiSalen)s), abbreviated as poly(meso-NiSaldMe) and poly(NiSaltMe). These two polymers, with different configurations of methyl substituents on the imine bridge, were used as precursors for the preparation of electrocatalytically active nickel hydroxide [Ni(OH)2]-type nanoparticles (NPs) anchored in the polymeric matrix as poly[SalenNi(OH)2]. The use of potentiodynamic and potentiostatic electropolymerization conditions for the deposition of polymeric precursors allowed us to control the molecular architecture of poly(NiSalen)s and NPs derived from them. Thus, we obtained different arrangements of NPs embedded in morphologically different poly(Salen) matrixes, indicating their electrocatalytic activity toward ethanol to different extents. Moreover, we found a direct relationship between the electrochemical stability of the poly(NiSalen) precursors operating in the organic solvent-based electrolyte solutions and the easiness of their transformation into Ni(OH)2 NPs operating in the aqueous alkaline media. Poly(NiSalen)s and Ni(OH)2-type NPs were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy.

Electrocatalytic Properties of Ni(II) Schiff Base Complex Polymer Films

Platinum electrodes were modified with polymers of the (±)-trans-N,N'-bis(salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn)]) and (±)-trans-N,N'-bis(3,3'-tert-Bu-salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn(Bu))]) complexes to study their electrocatalytic and electroanalytical properties. Poly[Ni(salcn)] and poly[Ni(salcn(Bu))]) modified electrodes catalyze the oxidation of catechol, aspartic acid and NO2-. In the case of poly[Ni(salcn)] modified electrodes, the electrocatalysis process depends on the electroactive surface coverage. The films with low electroactive surface coverage are only a barrier in the path of the reducer to the electrode surface. The films with more electroactive surface coverage ensure both electrocatalysis inside the film and oxidation of the reducer directly on the electrode surface. In the films with the most electroactive surface coverage, electrocatalysis occurs only at the polymer-solution interface. The analysis was based on cyclic voltammetry, EQCM (electrochemical quartz crystal microbalance) and rotating disc electrode method.

Redox-conducting polymers based on metal-salen complexes for energy storage applications

Metal-salen polymers are electrochemically active metallopolymers functionalized with multiple redox centers, with a potential for high performance in various fields such as heterogeneous catalysis, chemical sensors, energy conversion, saving, and storage. In light of the growing world demand for the development of superior energy storage systems, the prospects of employing these polymers for advancing the performance of supercapacitors and lithium-ion batteries are particularly interesting. This article provides a general overview of the results of investigating key structure-property relationships of metal-salen polymers and using them to design polymer-modified electrodes with improved energy storage characteristics. The results of independent and collaborative studies conducted by the members of two research groups currently affiliated to the Saint–Petersburg State University and the Ioffe Institute, respectively, along with the related data from other studies are presented in this review.