Introduction of N-substituted dithienylpyrrole into the backbone of poly-thiophenes allows the fine-tuning of the electrochemical properties in the resulting copolymers. The electrochemical, spectroscopic, and electrical properties were characterized across their different neutral and charged states by means of ex-situ and in-situ techniques revealing that the SNSBA comonomer not only influences the optoelectronic properties but improves the insulating/conducting transition.

Abstract

Conducting polymers find applications as active materials in electrochromic devices thanks to their tunable optoelectronic and electrochemical properties. Such versatility can be further enhanced by copolymerizing various aromatic monomers in order to produce new materials. In this work, we present different copolymers obtained by electropolymerization of an N-substituted dithienylpyrrole (SNSBA) with either 3,4-ethylendioxythiophene (EDOT) or bithiophene (BTh). The electrochemical, spectroscopic, and electrical properties were characterized across their different neutral and charged states by means of ex-situ and in-situ spectroelectrochemical techniques. The peculiar feature of SNSBA lies in the aniline bearing substituent of the central pyrrole unit that allows polymerization to occur at three different sites, yielding a cross-linked polymer network. Our findings show that the SNSBA comonomer not only influences the optoelectronic properties of the final materials with respect to their homopolymers, but also induces a lowering of the hysteresis of the insulating/conducting transition (ΔE_G <280 mV), likely due to the cross-linked nature of the polymer layer. These features are promising to develop a new class of copolymers for electrochromic devices with stable, reversible, and fast operation.

Electrochemical impedance spectroscopy is a sensitive research technique for gaining insights into the underlying mechanisms of battery systems. The authors present a physical impedance model that explains the three-stage mechanism of lithium-ion intercalation into graphite electrodes, using a two-electrode coin cell configuration across two initial lithiation and delithiation cycles. Important electrochemical parameters are provided and validated through these cycles. The results provide valuable insights and can serve as a benchmark for the future research.

Abstract

Graphite electrodes are widely used in commercial metal-ion batteries as anodes. Electrochemical impedance spectroscopy serves as one of the primary non-destructive techniques to obtain key information about various batteries during their operation. However, interpretation of the impedance response of graphite electrodes in contact with common organic electrolytes can be complicated. It is especially challenging, particularly when utilizing the 2-electrode configuration that is common in battery research. In this work, we elaborate on a physical impedance model capable of accurately describing the impedance spectra of a graphite|electrolyte|metallic Li system in a coin-cell assembly during two initial charge/discharge cycles. We analyze the dependencies of the model parameters for graphite and metallic lithium as a function of the state of charge to verify the model. Additionally, we suggest that the double layer capacitance values obtained during specific intercalation stages could help to determine if the area-normalized values align with the expected range. The data and the procedure necessary for calibration are provided.

“Utilizing sunlight to directly generate fuels using photoelectrochemical reactions is a promising route to renewable, net carbon-neutral fuels. However, a common problem in this field is semiconductor degradation in aqueous environments. Transparent conductive encapsulants (TCEs) are tested to protect semiconductor photoelectrodes for solar fuel generation. TCE electrochemical performance is characterized and TCEs successfully help retain the photovoltage of protected photoelectrodes….“ Learn more about the story behind the research featured on the front cover in this issue's Cover Profile. Read the corresponding Research Article at 10.1002/celc.202300209.

Abstract

Invited for this issue's Front Cover is a group of researchers from the Materials, Chemistry, and Computational Science Directorate at the National Renewable Energy Laboratory, led by Dr. Ann L. Greenaway. The front cover picture shows the surface of a TCE sheet, with the metallized spheres that act as conductive pathways from the semiconductor surface, through the polymer matrix, to the electrochemical interface. The rainbow represents the light going through the TCE layer to the semiconductor below. The primary electrochemical reaction used in this work was the first reduction of methyl viologen, as illustrated with the floating chemical structures. Cover design by Talysa Klein (https://www.tk2.design/). Read the full text of the Research Article at 10.1002/celc.202300209.

Interconnected-branched anodically oxidized tin nanowires: This electrode is produced via electrodeposition on aluminum anodic oxide (AAO) template followed by anodic oxidation. The electrode gave ~87 % Faradaic efficiency for formate with −14.55 mA cm⁻² current density. It preserved the product selectivity for 12 h with a slight decline in current density. (RE: Reference electrode).

Abstract

In this study, we used a specially designed aluminum anodic oxide (AAO) template technique to produce interconnected self-standing tin nanowire electrocatalysts having a high surface-to-volume ratio for CO₂ reduction toward formate. These electrodes consisted of interconnected tin nanowires with 150 nm diameter and 7 μm length supported on 70–100 μm thick tin film. As prepared electrodes produced 6 times higher formate than the flat tin sheets, yet Faradaic efficiencies (FE%) were unsatisfactory. The main reason for low FE% is determined as the etching of native oxide on tin nanowires during hot alkali treatment to remove AAO and remnant aluminum. Porous anodic oxidation in 1 M NaOH solution was realized to recover tin oxides on the surface. Anodized tin nanowire electrocatalysts produced higher formate than anodized tin sheets, reaching FE_formate% of ~87 at −1 V vs. RHE cathodic reduction potential. Moreover, while anodic oxide on flat tin flaked off the surface in 1 h, these electrodes preserved their integrity and formate production ability even after 12 h.

Key areas of electrolytes in zinc-ion batteries (ZIBs) requiring attention include understanding the mechanisms of side reactions and developing cost-effective, scalable manufacturing processes with readily available electrolytes materials. By effectively mitigating side reactions, researchers can enhance ZIBs efficiency and lifespan, enabling them to compete with lithium-ion batteries (LIBs), particularly in grid energy storage applications.

Abstract

The paper discusses the challenges associated with the performance of zinc-ion batteries (ZIBs), such as side reactions that lead to reduced capacity and lifespan. The strategies for mitigating side reactions in ZIBs, including additives, electrolyte-electrode interface modification, and electrolyte composition optimization, are explored. Combinations of these approaches may be necessary to achieve the best performance for ZIBs. However, continued research is needed to improve the commercial viability of ZIBs. Areas of research requiring attention include the understanding of the mechanisms behind side reactions in ZIBs and the development of cost-effective and scalable manufacturing processes for ZIBs with available electrolyte. By developing effective strategies for mitigating side reactions, researchers can improve the efficiency and lifespan of ZIBs, making them more competitive with lithium-ion batteries in various applications, including grid energy storage.

Sensing it: A simple and easy-to-use electrochemical sensor connected to a smartphone was designed for rapid and sensitive detection of bisphenol A (BPA) in water samples. By combining a nanocomposite of Mg_0.5Co_2.5(PO₄)₂ and carbon black on screen printed electrode surface, the sensor displayed high electrocatalytic activity towards BPA with a wide range of linearity and low detection limit.

Abstract

Bisphenol A (BPA) widely recognized as an endocrine disruptor can induce serious threats to human health such as sexual anomalies and cancer. Unfortunately, BPA has been increasingly used since 1950s; specifically during the manufacturing of polycarbonates and plastics such as food containers and water bottles. Thus, there is an urgent need to develop low-cost, simple, portable and sensitive sensors for in-situ detection of this contaminant in food and water. The combination of nanostructured carbon materials and metal/metal oxide nanoparticles can result in materials with unique physicochemical properties as well as excellent catalytic behaviors. Herein, we propose a smartphone-assisted electrochemical sensor based on the combination of Mg_0.5Co_2.5(PO₄)₂ and carbon black (CB) modified screen-printed electrode (SPE) for a rapid and sensitive determination of BPA. Structural characterization confirmed the formation of Mg_0.5Co_2.5(PO₄)₂/CB nanocomposite on SPE surface. Very low oxidation potential of BPA was observed during the differential pulse voltammetry (DPV) experiments at 0.16 V vs. Ag/AgCl. The sensor revealed two-step linear response from 0.5–6.5 μm and from 16.5–100 μm with a lower limit of detection (LOD) of 0.15 μm. A good reproducibility, excellent stability, and high interference-free ability were obtained. Furthermore, the developed sensor showed satisfactory recoveries for BPA detection in real water samples.

The changes in net charge during the redox reaction indicated that the transition metal serves as the redox center in olivine materials and aqua-complexes, whereas the O atom serves as the redox center in oxide-based layered and spinel materials. A correlation exists between the redox center and electrode potential of these materials.

Abstract

Li-insertion materials employed as electrode materials in Li-ion batteries undergo solid-state redox reactions wherein ions within a solid matrix are oxidized and reduced, in contrast to the conventional redox reactions of ions in solution. However, owing to the lack of a comprehensive theory for solid-state redox reactions, the electrode potential of Li-insertion materials remains unexplained from a theoretical standpoint. This limitation impedes the rational design of positive and negative electrodes with higher and lower potentials, respectively. This study employs the DV-Xα method to calculate the electronic structures of various Li-insertion materials and transition-metal aqua-complexes associated with the redox reaction to shed light on the corresponding solid-state redox potentials. Notably, the transition-metal ion is identified as the redox center in olivine materials and aqua-complexes, which exhibit similar electrode potentials, whereas the oxide ion is identified as the redox center in layered and spinel oxide materials, which show significant differences in electrode potential compared with olivine materials. These findings imply a correlation between the electrode potential and redox center in Li-insertion materials. The results of this study reveal that the electrode potential of Li-insertion materials is determined by their redox center rather than their constituent elements.

The Front Cover illustrates a TCE sheet, where the rainbow is the light reaching the photoelectrode, the spheres are the conductive pathway through the polymer matrix to the electrochemical interface, and the methyl viologen redox couple is reduced in the solution. Cover design by Talysa Klein (www.tk2.design). More information can be found in the Research Article by G. A. Rome et al.

Kerf-loss powder from wafering of solar cells are characterized thoroughly and shown to consist of nanoscale crystallites in an amorphous matrix. The powders are analyzed for chemical composition, morphology, crystallinity, and finally the amorphous influence on the first electrochemical cycle.

Abstract

Silicon powder kerf loss from diamond wire sawing in the photovoltaic wafering industry is a highly appealing source material for use in lithium-ion battery negative electrodes. Here, it is demonstrated for the first time that the kerf particles from three independent sources contain ~50 % amorphous silicon. The crystalline phase is in the shape of nano-scale crystalline inclusions in an amorphous matrix. From literature on wafering technology looking at wafer quality, the origin and mechanisms responsible for the amorphous content in the kerf loss powder are explained. In order to better understand for which applications the material could be a valuable raw material, the amorphicity and other relevant features are thoroughly investigated by a large amount of experimental methods. Furthermore, the kerf powder was crystallized and compared to the partly amorphous sample by operando X-ray powder diffraction experiments during battery cycling, demonstrating that the powders are relevant for further investigation and development for battery applications.

Electrochemical ethanol oxidation reaction: The reaction pathway significantly influences the overall performance of the electrochemical ethanol oxidation reaction (EOR), which can be effectively characterized through in situ Raman spectroscopy. In this concept, we concentrate on the fundamentals of the EOR pathway and the notable advancements made in EOR mechanism studies utilizing in situ Raman spectroscopy.

Abstract

The Electrochemical Ethanol Oxidation Reaction (EOR) plays a pivotal role in next-generation energy conversion devices. A clear understanding of the EOR reaction mechanism is critical for rational catalyst design, a task complicated by the numerous reaction intermediates and pathways involved. To this end, in situ Raman spectroscopy has proven invaluable in identifying many such intermediates at the electrode/electrolyte interface under varying applied potentials. Therefore, this technique allows for inference of the reaction mechanism based on the detected Raman signals of intermediates and observed structural changes, positioning in situ Raman spectroscopy as one of the most suitable methods for studying the EOR reaction mechanism. In this short review, with an eye towards future applications, we concentrate on the essential fundamentals of EOR and highlight recent advancements in understanding the EOR mechanism by in situ Raman spectroscopy.