Search

Carbon capture and storage (CCS) is essential if global warming mitigation scenarios are to be met. However, today's maturing thermochemical capture technologies have exceedingly high energy requirements and rigid form factors that restrict their versatility and limit scale. Using renewable electricity, rather than heat, as the energy input to drive CO2 separations provides a compelling alternative to surpass these limitations. Although electrochemical technologies have been extensively developed for energy storage and CO2 utilization processes, the potential for more expansive intersection of electrochemistry with CCS is only recently receiving growing attention, with multiple scientific proofs-of-concept and a burgeoning pipeline with numerous concepts at various stages of technology readiness. Here, we describe the emerging science and research progress underlying electrochemical CCS processes and assess their current maturity and trajectory. We also highlight emerging ideas that are ripe for continued research and development, which will allow the impact of electrochemical CCS to be properly assessed in coming years. [ABSTRACT FROM AUTHOR]

Electrochemically mediated redox‐active processes are gaining momentum as a promising liquid‐phase separation technology. Compared to conventional systems, they offer potential benefits, such as smaller energy footprints, nondestructive operation, reversibility, and tunability for specific analyte removal, with clear applications to societal and industrial challenges like water treatment and chemical synthesis. An asymmetric Faradaic cell heterogeneously functionalized with a metallopolymer at the anode and a hexacyanoferrate material at the cathode is presented for the first time. The redox‐active species' iron centers enhance the electrosorption of heavy metal oxyanions with up to 98% removal in the ppb range, and offer tunable operating windows as low as ≈0.1 V at ≈1 A m−2. By avoiding water splitting, the hexacyanoferrate cathode imparts additional advantages, namely a four‐fold reduction in adsorption energy requirements, full suppression of solution pH increase, and the ability to capture redox‐active catalytic anions such as polyoxometalates without altering their bulk oxidation state. This hybrid framework of a polymeric ferrocene anode and crystalline hexacyanoferrate cathode allows for simultaneous and synergistic uptake of anions and cations, respectively, creating a new asymmetric scheme for water‐based separations, with foreseeable future extension to fields such as ion‐sensing, energy storage, and electrocatalysis. [ABSTRACT FROM AUTHOR]

Abstract: Performance stability of electrochemically active polymers (EAPs) remains one of the greatest and long‐standing challenges with regard to EAP‐based technologies for a myriad of energy, biomedical, and environmental applications. The performance instability of EAPs originates from their structural alteration under repeated charge–discharge cycling and/or flexing. In this work, a conceptually new “soft confinement” strategy to enhance EAP performance stability, including cyclic and mechanical, by using rationally designed, vapor‐deposited organic networks is presented. These chemically cross‐linked networks, when in contact with an electrolyte solution, turn into ultrathin, elastic hydrogel coatings that encapsulate conformally the EAP micro‐/nanostructures. Such hydrogel coatings allow easy passage of ions that intercalate with EAPs, while simultaneously mitigating the structural pulverization of the EAPs and/or their detachment from substrates. Fundamentally distinct from extensively studied “scaffolding” or “synthetic” approaches to stabilizing EAPs, this soft confinement strategy relies on a postmodification step completely decoupled from the EAP synthesis/fabrication, and enjoys the unique advantage of substrate‐independency. Hence, this strategy is broadly applicable to various types of EAPs. The proposed stability enhancement strategy is demonstrated to be effective for a range of EAP systems with differing chemical and morphological characteristics under various testing conditions (repeated charging/discharging, bending, and twisting). [ABSTRACT FROM AUTHOR]

Unconjugated redox polymers, such as polyvinylferrocene (PVF), have rarely been used for energy storage due to their low intrinsic conductivity. Conducting polymers with conjugated backbones, though conductive, may suffer from insufficient exposure to the electrolyte due to the often formed nonporous structures. The present work overcomes this limitation via simultaneous electropolymerization of pyrrole and electroprecipitation of PVF on electrode surfaces. This synthesis method relies on the π-π stacking interactions between the aromatic pyrrole monomers and the metallocene moieties of PVF. This fabrication process results in a highly porous polymer film, which enhances the ion accessibility to polypyrrole (PPy). PPy serves as a 'molecular wire,' improving the electronic conductivity of the hybrid and the utilization efficiency of ferrocene. The PVF/PPy hybrid exhibited a specific capacitance of 514.1 F g−1 , which significantly exceeds those of PPy (27.3 F g−1), respectively. This approach offers an alternative to nanocarbon materials for improving the electronic conductivity of polymer hybrids, and suggests a new strategy for fabricating nanostructured polymer hybrids. This strategy can potentially be applied to various polymers with π-conjugated backbones and redox polymers with metallocene moieties for applications such as energy storage, sensing, and catalysis. [ABSTRACT FROM AUTHOR]−1), respectively. This approach offers an alternative to nanocarbon materials for improving the electronic conductivity of polymer hybrids, and suggests a new strategy for fabricating nanostructured polymer hybrids. This strategy can potentially be applied to various polymers with π-conjugated backbones and redox polymers with metallocene moieties for applications such as energy storage, sensing, and catalysis. [ABSTRACT FROM AUTHOR]

With the current rising world demand for energy sufficiency, there is an increased necessity for the development of efficient energy storage devices. To address these needs, the scientific community has focused on the improvement of the electrochemical properties of the most well known energy storage devices; the Li-ion batteries and electrochemical capacitors, also called supercapacitors. Despite the fact that supercapacitors exhibit high power densities, good reversibility and long cycle life, they still exhibit lower energy densities than batteries, which limit their practical application. Various strategies have been employed to circumvent this problem, specifically targetting an increase in the specific capacitance and the broadening of the potential window of operation of these systems. In recent years, sophisticated surface design and engineering of hierarchical hybrid nanostructures has facilitated significant improvements in the specific and volumetric storage capabilities of supercapacitors. These nanostructured electrodes exhibit higher surface areas for ion adsorption and reduced ion diffusion lengths for the electrolyte ions. Significant advances have also been achieved in broadening the electrochemical window of operation of these systems, as realized via the development of asymmetric two-electrode cells consisting of nanocomposite positive and negative electrodes with complementary electrochemical windows, which operate in environmentally benign aqueous media. We provide an overview of the diverse approaches, in terms of chemistry and nanoscale architecture, employed recently for the development of asymmetric supercapacitors of improved electrochemical performance. [ABSTRACT FROM AUTHOR]

Summary Carbon materials are important for many electrochemical applications due to their tunable electron-transfer and charge-storage properties. Judicious structural manipulation of carbon to modulate its chemical, electronic, and crystalline properties is key to the rational design of many high-performance electrochemical devices. Here we focus on three types of carbon nanomaterials of recent interest in electrochemistry, namely, carbon nanofibers, carbon nanotubes, and graphene. We concentrate on how structural variations in these carbon nanomaterials impact their electrochemical activities. In this review, following a brief overview of the synthesis methods for each class of carbon nanomaterials, we discuss their electrochemical applications for sensing, electrocatalysis, and energy storage, with emphasis on general carbon structure manipulation strategies that impart specific functionalities to suit each application area. Special attention is devoted to articulating how the electronic structure of carbon influences its electrochemical activity. Through the analysis of different electrochemical devices, we find that some of the modification techniques apply to more than one application area; thus structural manipulation methods in one class of electrochemical devices may be extended to other types. [ABSTRACT FROM AUTHOR]

Abstract Over recent decades, a new type of electric energy storage system has emerged with the principle that the electric charge can be stored not only at the interface between the electrode and the electrolyte but also in the bulk electrolyte by redox activities of the electrolyte itself. Those redox electrolytes are promising for non-flow hybrid energy storage systems, or redox electrolyte-aided hybrid energy storage (REHES) systems; particularly, when they are combined with highly porous carbon electrodes. In this review paper, critical design considerations for the REHES systems are discussed as well as the effective electrochemical characterization techniques. Appropriate evaluation of the electrochemical performance is discussed thoroughly, including advanced analytical techniques for the determination of the electrochemical stability of the redox electrolytes and self-discharge rate. Additionally, critical summary tables for the recent progress on REHES systems are provided. Furthermore, the unique synergistic combination of porous carbon materials and redox electrolytes is introduced in terms of the diffusion, adsorption, and electrochemical kinetics modulating energy storage in REHES systems. [ABSTRACT FROM AUTHOR]

We report the systematic structuralmanipulation of turbostraticelectrospun carbon nanofibers (ECNFs) using a microwave-assisted oxidationprocess, which is extremely rapid and highly controllable and affordscontrolled variation of the capacitive energy storage capabilitiesof ECNFs. We find a nonmonotonic relationship between the oxidationdegree of ECNFs and their electrocapacitive performance and presenta detailed study on the electronic and crystalline structures of ECNFsto elucidate the origin of this nonmonotonic relation. The ECNFs withan optimized oxidation level show ultrahigh capacitances at high operationrates, exceptional cycling performance, and an excellent energy–powercombination. We have identified three key factors required for optimalenergy storage performance for turbostratic carbon systems: (i) anabundance of surface oxides, (ii) microstructural integrity, and (iii)an appropriate interlayer spacing. [ABSTRACT FROM AUTHOR]