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Redox‐conducting polymers based on SalEn‐type complexes have attracted considerable attention due to their potential applications in electrochemical devices. However, their charge transfer mechanisms, physical and electrochemical properties remain unclear, hindering their rational design and optimization. This study aims to establish the influence of monomer geometry on the polymer's properties by investigating the properties of novel nonplanar SalEn‐type complexes, poly[N,N'‐bis(salicylidene)propylene‐2‐(hydroxy)diaminonickel(II)], and its analog with 2,2,6,6‐tetramethylpiperidinyl‐N‐oxyl (TEMPO)‐substituted bridge (MTS). To elucidate the charge transfer mechanism, operando UV–Vis spectroelectrochemical analysis, electrochemical impedance spectroscopy, and electron paramagnetic resonance are employed. Introducing TEMPO into the bridge moiety enhanced the specific capacity of the poly(MTS) material to 95 mA h g−1, attributed to TEMPO's and conductive backbone's charge storage capabilities. Replacement of the ethylenediimino‐bridge with a 1,3‐propylenediimino‐ bridge induced significant changes in the complex geometry and material's morphology, electrochemical, and spectral properties. At nearly the same potential, polaron and bipolaron particles emerged, suggesting intriguing features at the overlap point of the electroactivity potentials ranges of polaron–bipolaron and TEMPO, such as a disruption in the connection between TEMPO and the conjugation chain or intramolecular charge transfer. These results offer valuable insights for optimizing strategies to create organic materials with tailored properties for use in catalysis and battery applications. [ABSTRACT FROM AUTHOR]

Electroactive polymer materials are known to play important roles in a vast spectrum of modern applications such as in supercapacitors, fuel cells, batteries, medicine, and smart materials, etc. They are usually divided into two main groups: first, conducting π-conjugated organic polymers, which conduct electricity by cation-radicals delocalized over a polymer chain; second, redox polymers, which conduct electricity via an electron-hopping mechanism. Polymer materials belonging to these two main groups have been thoroughly studied and their thermodynamic and kinetic models have been built. However, in recent decades a lot of mixed-type materials have been discovered and investigated. To the best of our knowledge, a thermodynamic-based description of conducting redox polymers (CRPs) has not been provided yet. In this work, we present a thermodynamic model for voltammetric responses of conducting redox polymers. The derived model allows one to extract thermodynamic parameters of a CRP including the polaron delocalization degree and redox active groups interaction constant. The model was verified with voltammetric experiments on three recently synthesized CRPs and showed a satisfactory predictive ability. The simulated data are in good agreement with the experiment. We believe that developing theoretical descriptions for CRPs and other types of electroactive materials with the ability to simulate their electrochemical responses may help in future realization of new systems with superior characteristics for electrochemical energy storage, chemical sensors, pharmacological applications, etc. [ABSTRACT FROM AUTHOR]

TEMPO-containing conductive polymers are used in organic electronics due to their electrochemical properties. One of significant limitations in developing such materials is the structural modification by several TEMPO moieties. Here, we report a synthesis of the first-generation dendrimer containing two TEMPO fragments, bis(2,2,6,6-tetramethyl-1-(λ1-oxidaneyl)piperidin-4-yl) 3,3′-((2-hydroxyethyl)azanediyl)dipropionate, that can be implemented into a conductive polymer structure. The resulting product was characterized using 1H and 13C nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectroscopy (HRMS). [ABSTRACT FROM AUTHOR]

Various iron oxides have been proven to be promising anode materials for metal-ion batteries due to their natural abundance, high theoretical capacity, ease of preparation, and environmental friendliness. However, the synthesis of iron oxide-based composites requires complex approaches, especially when it comes to composites with intrinsically conductive polymers. In this work, we propose a one-step microplasma synthesis of polyaniline-coated urchin-like FeOOH nanoparticles (FeOOH/PANI) for applications as anodes in lithium-ion batteries. The material shows excellent electrochemical properties, providing an initial capacity of ca. 1600 mA∙h∙g−1 at 0.05 A∙g−1 and 900 mA∙g−1 at 1.2 A∙g−1. Further cycling led to a capacity decrease to 150 mA∙h∙g−1 by the 60th cycle, followed by a recovery that maintained the capacity at 767 mA∙h∙g−1 after 2000 cycles at 1.2 A∙g−1 and restored the full initial capacity of 1600 mA∙h∙g−1 at a low current density of 0.05 A∙g−1. Electrochemical milling—the phenomenon we confirmed via a combination of physico-chemical and electrochemical techniques—caused the material to exhibit interesting behavior. The anodes also exhibited high performance in a full cell with NMC532, which provided an energy density of 224 Wh∙kg−1, comparable to the reference cell with a graphite anode (264 Wh∙kg−1). [ABSTRACT FROM AUTHOR]

This document, titled "Catalysts in Energy Applications," explores the role of catalysis in various energy processes. It highlights the importance of catalytic reactions in traditional fossil fuel production and the transition towards sustainable energy alternatives such as biofuel production and CO2 capture. The document also discusses the significance of catalysis in hydrogen production, storage, and utilization, as well as in the development of materials and processes for artificial photosynthesis. The research papers presented in this Special Issue delve into the intricacies of catalytic processes in energy-related domains, including oxygen reduction reactions, CO2 conversion, and the electrooxidation of urea. These contributions provide valuable insights into the field of energy catalysis and offer potential advancements in more efficient and sustainable energy conversion technologies. [Extracted from the article]

A comparative study of the electronic structure of the salen ligand in the H2(Salen) molecule and the [Ni(Salen)] complex was performed using the experimental methods of XPS, UV PES, and NEXAFS spectroscopy along with DFT calculations. Significant chemical shifts of +1.0 eV (carbon), +1.9 eV (nitrogen), and −0.4 eV (oxygen) were observed in the 1s PE spectra of the salen ligand atoms when passing from a molecule to a complex, unambiguously indicating a substantial redistribution of the valence electron density between these atoms. It is proposed that the electron density transfer to the O atoms in [Ni(Salen)] occurred not only from the Ni atom, but also from the N and C atoms. This process seemed to be realized through the delocalized conjugated π-system of the phenol C 2p electronic states of the ligand molecule. The DFT calculations (total and partial DOS) for the valence band H2(Salen) and [Ni(Salen)] described well the spectral shape of the UV PE spectra of both compounds and confirmed their experimental identification. An analysis of the N and O 1s NEXAFS spectra clearly indicated that the atomic structure of the ethylenediamine and phenol fragments was retained upon passing from the free salen ligand to the nickel complex. [ABSTRACT FROM AUTHOR]

Polypyrroles attract significant attention as the promising class of conductive polymers for the organic electronics, electrochemical energy-storage, photovoltaics, sensing and light-emitting devices due to their electrochemical and electrical properties. The attachment of the charged fragments to the pyrrole monomeric unit opens the route to a water-soluble polypyrrole for improved solution processability. Here we report a scalable multigram synthesis of the N-substituted cationic pyrrole, N,N,N-triethyl-4-(1H-pyrrol-1-yl)butan-1-aminium perchlorate, which can be used for the preparation of the water-soluble cationic polypyrrole, in two steps with 81% overall yield. The resulting product was characterized by the 1H and 13C, nuclear magnetic resonance (NMR), ESI-high-resolution mass spectrometry (ESI-HRMS) and Fourier-transform infrared spectroscopy (FTIR). [ABSTRACT FROM AUTHOR]