ChemElectroChem最新文献

The widespread use of the water-soluble paraquat (PQ) herbicide has found to be linked with numerous toxic outcomes to humans as well as aquatic animals, while the on-site and rapid measurement is still challenging due to unsuitability and lack of selectivity of the existing techniques. This study presents a selective, sensitive, and low-cost electrochemical sensor for detecting residual PQ in water by combining a core–shell molecularly imprinted polymer (MIP)@SiO₂@Fe₃O₄ material with a portable screen-printed carbon electrode (SPCE). Adsorptive stripping voltammetry (AdSV) was employed to determine PQ using the proposed MIP@SiO₂@Fe₃O₄/SPCE, exhibiting high analytical performance with a sensitivity of 7.27 µA/µM, a two-segment linear range of 0.25–20 and 20–50 µM, and a detection limit of 0.043 µM. In addition, excellent selectivity towards PQ was achieved, even in the presence of a 20-fold excess of interfering substances commonly found in various water matrices. Recoveries of 89.72%–113.46% were obtained at the MIP@SiO₂@Fe₃O₄/SPCE for the determination of PQ in tap water, river water, and seawater samples, and the results were validated using high-performance liquid chromatography, demonstrating its strong potential for practical applications in aquatic analysis.

Aromatic carboxylic acids are attractive feedstocks owing to their stability, commercial abundance, and widespread presence in pharmaceuticals and functional molecules. However, their direct decarboxylation under mild conditions has remained a longstanding challenge because of the slow fragmentation of aroyloxyl radicals and the prevalence of competing pathways. Herein, we report an electrochemical decarboxylative borylation of aryl carboxylic acids enabled by rapid alternating polarity (rAP) using reticulated vitreous carbon (RVC) electrodes. The protocol operates at ambient temperature without transition metals or external oxidants, delivering aryl boronic acid esters directly from abundant aromatic acid feedstocks. In addition to its synthetic utility, the method exhibits markedly lower energy intensity than previously reported photochemical decarboxylation platforms, highlighting its potential as a scalable and sustainable strategy for the direct conversion of abundant aromatic acid feedstocks into valuable organoboron building blocks.

Lithium-sulfur (Li-S) batteries are one of the popular choices for the high energy storage systems due to their high theoretical energy density, cheap raw materials, and environmental friendliness. This work adopts a hydrothermal method to prepare covalent organic frameworks (COFs). Bi₂Se₃ nanosheets are synthesized on COFs to obtain Bi₂Se₃/COFs composites serving as sulfur hosts. The porous COFs accommodate active sulfur and restrain the diffusion and migration of lithium polysulfides simultaneously. Furthermore, polar Bi₂Se₃ immobilizes lithium polysulfides via chemical adsorption and efficiently alleviates the shuttle effect. Its layered nanostructure not only improves the structural stability of the cathode, but also endows the composites with superior electrical conductivity to accelerate the the redox reaction of sulfur. The results illustrate that the S/Bi₂Se₃/COFs electrode shows a remarkable initial discharge specific capacity of 961.2 mAh g⁻¹ at 0.5 C. After 700 cycles, the capacity decay rate is 0.047% per cycle, showing excellent cycle stability. Therefore, the Bi₂Se₃/COFs are a desirable sulfur-loading host for high-performance Li-S batteries.

The electrochemical characterization of cultural heritage objects requires noninvasive approaches. In the case of patina-covered bronze objects, two essential features of the setups recently proposed to satisfy this requirement are (i) the use of gel electrolytes and (ii) the absence of metal contacts that might damage the patina (or, at least, the control of the size of the damaged area to make it invisible to the naked eye). In the present work we show how the impedance of model coins is most conveniently measured using a four-electrode setup where the sample is mounted in a symmetrical two-compartment cell filled with a gel electrolyte which contacts both coin faces. Results are presented for model coins with polished surfaces, patina-covered coins, coins pretreated with a corrosion inhibitor (benzotriazole), and coins coated with a commercial acrylate/methacrylate copolymer (Paraloid B-72^(R)). Compared with alternative approaches involving two-electrode or three-electrode setups, our approach is the only one which simultaneously warrants a noninvasive character and the direct determination of the sample impedance without needing any correction. Although only model coins were used in this study, the above conclusion applies as well to true archaeological coins.

Bromine retention in aqueous redox flow batteries can be improved by complexation, but the resulting gain in stability is often accompanied by losses in electrochemical accessibility and transport. Here, we investigate a ferri-/ferrocyanide–bromine flow battery based on soluble ferri-/ferrocyanide and bromine/bromide redox electrolytes. Three bromine/bromide positive-electrolyte conditions were compared: a pristine bromide electrolyte, an electrolyte containing the bromine-complexing agent (BCA) N-ethyl-N-methylpyrrolidinium bromide ([EMPyrr]Br), and the same electrolyte after nitrogen presparging. Charge–capacity retention after 70 cycles increased from 23.4% for the pristine electrolyte to 34.9% with [EMPyrr]Br and 66.0% with [EMPyrr]Br and nitrogen presparging. Because neither a nitrogen-pre-sparged BCA-free control nor an alternative inert-gas control was examined, the higher retention cannot be attributed uniquely to nitrogen; deaeration and sparging-induced redistribution of bromine-rich phases may also contribute. Improved retention was accompanied by increased polarization, higher ex situ electrolyte impedance, and an initial voltage rise associated with bromine-rich phase formation. Postcycling cyclic voltammetry provides qualitative evidence of bromine crossover, while Raman spectroscopy shows condition-dependent bromine-related signatures in the sampled liquid phase. These findings show that improved charge–capacity retention does not necessarily translate into better cell performance unless the retained bromine remains electrochemically accessible.

Spatiotemporal modulation of electrochemical gradients to control enzyme activity in biological systems has been achieved using programmable chemical actuators (PCAs). The electronic-ionic coupling by polypyrrole is the operational physics foundation of PCAs. In a previous study, pH-indicating dyes were used to measure the effects of potential application techniques on the temporal control over the gradient. Also, when PCAs were operated under duplex pulse amperometry, the duty cycle was studied as a control variable over soluble alkaline phosphatase activity. The data were used here to develop numerical models of the ion transport mechanisms in three PCAs differing in size and geometry based on finite element analysis. The models considered electric fields, ion flux, diffusion, and Coulombic repulsion and were implemented and solved with COMSOL Multiphysics using the Secondary Current Distribution and Transport of Diluted Species predefined application modes. The new models were able to accurately predict ion transport patterns induced by PCAs in a 6-well plate and a 10 mL beaker but were less accurate for a PCA in a semi-microcuvette, probably due to the dependence of current density on the surface roughness of the working electrode. Nonetheless, these models provide a good foundation to design PCAs for new applications.

MXene, a class of two-dimensional material have attracted wide attention as an energy storage material. In this work, a double transition metal MXene Ti₂NbC₂T_x was prepared via molten salt (MS) etching with controlled –Cl and –O terminations. The results demonstrate that the introduction of O-terminated MXene enhances electrochemical performance, resulting in a high Li⁺ storage capacity up to 320 mAh/g and high rate capability 220 mAh/g at 1C rate. These findings highlight double transition metal MXene prepared by MS etching as a promising negative electrode material for energy storage in a nonaqueous electrolyte.

Cellobiose dehydrogenase (CDH) is a fungal extracellular flavocytochrome crucial for biomass degradation and promising for bioelectrocatalytic applications. However, its practical application remains limited by suboptimal catalytic efficiency and inefficient electron transfer. Here, an integrated engineering strategy was developed that couples substrate-pocket modification with electron-transfer optimization to enhance overall catalytic cycle simultaneously. Structure-guided engineering identified beneficial substrate-pocket mutations, which were subsequently combined with the previously validated electron-transfer-enhancing mutations (W316H and A165C), yielding the triple mutant A165C-N313D-W316H. This variant exhibited a fourfold increase in catalytic specific activity and an 8.5-fold enhancement in electron transfer rate relative to the WT. Molecular dynamics simulations further revealed that the mutation improves the hydrogen-bonding network within the substrate-binding pocket. Moreover, the mutant retained high thermostability, displayed enhanced specificity toward lactose, and reduced hydrogen peroxide generation by 82% compared with the WT. When immobilized on electrodes, A165C-N313D-W316H showed substantially improved electrocatalytic performance. Under optimized conditions, the MET-based bioelectrocatalytic system achieved a 94% conversion yield of lactobionic acid within 18 h. This study demonstrates that the integration of substrate-pocket and electron-transfer engineering effectively improves the overall catalytic cycle of CDH and provides a promising approach for engineering multidomain redox enzymes.

Electrochemical palladium membrane reactors traditionally rely on direct cathodic polarization of the palladium membrane to drive hydrogen permeation. This work introduces the wireless electrochemical palladium membrane reactor (wPMR), a design that utilizes bipolar electrochemistry to actuate hydrogen transport without direct electrical connections to the membrane. By redefining the palladium membrane as an “ajar” bipolar electrode, we demonstrate that it functions similarly to a diode, requiring a voltage threshold to initiate selective hydrogen transport along an induced external electric field. As a proof-of-concept, we integrated the wPMR with lithium-mediated nitrogen reduction, successfully synthesizing ammonia using hydrogen atoms derived directly from water. Unlike conventional systems that suffer from structural deformation due to lattice expansion, the wPMR maintains membrane integrity by avoiding the lattice-expanded β-PdH. Through isotope labeling and operando monitoring, we confirm the synchronous operation of four Faradaic reactions within this reaction geometry. The wPMR thus emerges as a high-voltage electrosynthetic platform capable of directly delivering hydrogen from water to organic reactions.

Dual-network (DN) hydrogels possess tunable polymer network architectures, exceptional mechanical robustness, and superior water retention capability. They demonstrate substantial potential in structural optimization and performance stabilization, thus garnering widespread attention from both the academic and industrial sectors in the field of flexible devices such as supercapacitors, temperature sensors, and zinc-air batteries. Focusing on the gelation mechanisms of DN hydrogels, this review systematically classifies them into three categories according to different cross-linking interactions, namely Chemical crosslinking, physical crosslinking, and hybrid crosslinking. Notably, this review details optimization strategies for the electrical conductivity, temperature resistance, and mechanical properties of DN hydrogels, including porosity enhancement, conductive filler incorporation, the salt-in-water strategy, and network structure modulation. Finally, it elaborates on the applications of DN hydrogels in flexible devices (supercapacitors, temperature sensors, zinc-air batteries). Based on the aforementioned findings, an innovative and feasible strategic outlook is put forward, with the aim of facilitating the further advancement of these flexible devices.