Electrochemistry Communications最新文献

The size, geometry and arrangement of pores can significantly affect both the activity of electrocatalysts and the performance of supercapacitors. Electrochemical impedance spectroscopy (EIS) is a powerful, non-invasive diagnostic tool for characterizing porous conductive media. To date, the impedance of porous electrodes characterized by the distribution of pore sizes has been described only on the basis of numerical models. Here, for the first time, the impedance of such systems is provided in the form of analytical solutions valid in high and low frequency range. The model enables traditional equivalent circuit fitting to impedance of electrodes characterized by log–normal distribution of pore sizes. The analytical expressions for the circuit elements give access to the electrode idealized geometry in terms of log-normal distribution. The model was applied for the analysis of the electrochemical impedance of activated carbon electrode in a sulphuric acid solution. The width of pore size distribution, mean pore radius, pore length and the number of pores can be determined from a single impedance spectrum.

This study introduces the Theokane number ($T_k$) as a groundbreaking dimensionless number in Electrochemistry. $T_k$ enables the determination of the operating state of an electrochemical (EC) system—indicating whether it is in a transient state (characteristic of cyclic voltammetry) or a steady state (typical of linear sweep voltammetry)—based on a given combination of potential scan rate and residence time. It aims to bridge the gap between various voltamperometric methods. $T_k$ uniquely compares the duration of the potential scan applied to an EC system to the residence time of the reaction mixture at the electrode. This comparison is pertinent in environments ranging from microfluidic setups to macroscale reactors, including stirred vessels.

$T_k$ is particularly crucial for understanding the ‘continuous answer’ of an EC system subjected to voltamperometric polarization across a spectrum of potential scan and stirring rates. Voltammograms recorded in a micro-reactor under varying conditions highlight the influence of operating parameters on EC responses. The approach introduced in this study accomplish three key objectives: i) it validates the $T_k$ number through the comparison of experimental and simulation data, ii) it proposes a range for its applicability; and iii) it opens a new mode for analyzing EC responses. It is important to note that $T_k$ is applicable to both quasi-reversible and irreversible systems.

In order to inhibit dendritic growth and improve the cycle stability of lithium metal anodes (LMAs), a 3D Nanoporous Nickel Foam (NP-NF) collector with hierarchical porous structure is designed through a simple modification strategy of Ni Foam (NF). The strategy only involves two steps, i.e. electrodeposition of metal zinc and chemical dealloying to evolve nanoporous structure. The obtained NP-NF possesses hierarchical pores. The large pores of several hundreds of micrometers from Ni foam could facilitate fast Li⁺ transport in dynamics. The mesopores on the surface of 100 nm to 1 μm could provide spatial confinement for Li deposition. The increased specific surface area could also reduce the local current density of electrode and consequently suppress the growth of dendrites. In addition, the in-situ formed lithophilic NiO on the 3D NP-NF surface can uniformly induce Li⁺ deposition. Compared to the Ni foam skeleton, 3D NP-NF in LMAs presents a significantly improved Li plating/string stability with a high Coulombic efficiency of 95 % after 350 cycles with plating capacity of 1 mAh cm⁻² at a current density of 1 mA cm⁻². 3D NP-NF@Li|Li cell shows an ultra-low overpotential of 18 mV during the 500 cycles (1000 h) at a current density of 1 mA cm⁻². The 3D NP-NF@Li|LiFePO₄ can stably cycle for 300 times with the capacity retention of above 80 % at 1C. This work demonstrates that constructing a micro-nano 3D porous structure collector can inhibit dendritic growth and improve lifespan of LMAs.

This study explores how fluoroethylene carbonate (FEC) influences the solid electrolyte interface (SEI) layer formation during battery cycling process. FEC improves SEI properties, producing a uniform, chemically stable layer enriched with lithium fluoride. This enhances mechanical resilience and electrochemical stability. FEC also suppresses electrolyte deformation and decomposition, maintaining its initial state. The findings highlight the significance and comprehension of electrolyte additives, offering an electrolyte research pathway for improving Li-ion battery performance and durability.

In the last decades, a significant amount of research has been focused on the development of miniaturized and portable electrochemical sensors in the form of screen-printed electrodes (SPEs). When performing voltammetric measurements using SPEs, especially in the case of carbon-based electrodes, additional peaks can appear and overlap with analytes’ signals or otherwise interfere with results. Therefore, the development of pretreatment methods that enable the removal of interferences is of great importance for SPEs utilization, e.g. for sensor applications. Moreover, electrode pretreatment can also be used to improve electron transfer kinetics, including reversibility of the studied redox processes. In this work, we present the evaluation of different pretreatment methods using cyclic voltammetry and potentiostatic anodization, applied on an in-house graphite-glass composite working electrodes. With the use of X-ray photoelectron spectroscopy and scanning electron microscopy it was confirmed that the surface of working electrode was contaminated by sub-micrometer sized silver particles, which resulted in two interference peaks. Several strong acids, including H₂SO₄, HNO₃, and HCl, as well as phosphate buffer solution, were evaluated as electrolytes for electrochemical pretreatment. A rapid, simple, and low-cost pretreatment protocol that enables the removal of the interference peaks, as well as improved voltammetric signals for [Fe(CN)₆]^3−/4− redox probe was developed. We propose the optimal pretreatment method in H₂SO₄ as a protocol that could be universally applied for carbon, carbon-glass, or similar types of SPEs before performing voltammetric experiments and/or further modifications of SPEs.

The electrochemical behavior and catalytic properties of nickel oxide (NiOx) are enhanced through cathodic electroplating and subsequent electrochemical activation in an alkaline aqueous electrolyte. The electrochemical detection of ʟ-glutamate becomes feasible by introducing an amine group through immobilizing APTES ((3-aminopropyl)triethoxysilane) on the NiOx surface, resulting in a positive charge. The synergistic effect of electrochemically activated electroplated NiOx and the APTES-modified surface facilitates the effective electrochemical detection of trace ʟ-glutamate. The APTES-activated NiOx electrode exhibits a linear detection range of 0.2 nM to 2 mM for glutamate. This relatively wide concentration range is promising for the analysis of human biological fluids.

Bioelectrochemical systems with Cupriavidus necator present a viable solution for harnessing H₂/CO₂ mixtures as substrates, employing mediated electron transfer to an infinite electron acceptor in the form of an anode instead of O₂. Fourteen redox mediators were spectroelectrochemically characterized, and their efficiency was evaluated through screening with C. necator in common cuvettes with screen printed electrodes (e-Cuvettes). Key performance indicators, including total turnover number, reduction rate, and growth, were analyzed. Ferricyanide emerged as highly effective for anodic respiration, reaching a total turnover number of 8.38 over 120 h of cultivation. On the other hand, phenazine methosulfate exhibited the highest reduction rate at 2.49 mM h⁻¹ with a total of 5.16 turnovers. Contrary, growth impairment is reported for menadione, possibly leading to deficient anodic electron transfer. The utilization of a broad spectrum of these shuttle molecules highlights the potential for optimizing bioelectrochemical applications involving C. necator.

Functionalization of widely used graphene oxide (GO) can be beneficial not only in tuning its characteristics along with preventing the restacking of its layers and improving wettability but also in providing pseudocapacitance as a supercapacitor electrode. In this research, for the first time, the electrochemical performance of guanidine-functionalized graphene oxide (G-GO) examined by means of both computational and experimental methods. As a high-performance supercapacitor electrode, G-GO illustrates a high specific capacitance of 612F/g at the current density of 1.5 A/g together with extraordinary cyclic stability for 12,000 cycles at high current density of 10 A/g. Moreover, quantum capacitance together with the layer distance change during functionalization reaction, calculated via density functional theory (DFT), also exhibit the superior performance of G-GO.

An impedance-based biosensor for the ultrasensitive, selective, and label-free detection of a blood miRNA associated to Alzheimer disease (AD), miRNA-206, was developed. The principle was grounded in the changes in the charge transfer resistance (R_CT) as an effect of intramolecular forces between miRNAs and ferro/ferricyanide in a well-structured transducer platform. A compact well-ordered mixed monolayer made of co-immobilized miRNA capture to 6-mercapto-1-hexanol (MCH) in a 1:4 M ratio (at 37 °C), uplifted the performance of the sensor through effectively assisting the orientation of the oligonucleotides. In this work, the remarkable response of the sensor was generated through new insights into the use of different moieties of miRNA capture to MCH, aiming to control interfacial constants, surface densities, and hybridization efficiency.A very low limit of detection, 0.15 aM, is achieved and the sensor has a wide linear dynamic range (from 1 aM to 1 μM), high selectivity to mismatches, low non-specific binding of proteins (BSA) and good stability (<10 % change in response after 14 days storage). Importantly, the sensor successfully measured miRNA-206 concentrations in real plasma samples (>95 % recovery), correlating directly with qPCR results. Nanomolar concentrations of miRNA-206 were found in the plasma of confirmed AD patients, while healthy controls, had a concentration of pM or lower. The biosensor's ability to quantitatively detect miRNA-206 in plasma without target amplification, e.g., using PCR, is significant, opening the possibility of developing a point-of-care diagnostic device for AD screening, contributing to clinical trials and patient care.

This research introduces a chemistry-agnostic approach to achieve rapid and degradation-free battery charging via ultrasonic agitation. An ultrasonic device operating in the megahertz range was used to stimulate electrolyte flow from outside the cell. The acoustic streaming effect accelerates ion transport from the bulk electrolyte to the electrode surface and suppresses the formation of an ion depletion zone. An experimental setup was used to optically observe the formation of dendrites when the current imposed across two zinc electrodes exceeded the limiting current. Beyond this limit, diffusion alone cannot provide sufficient ions, resulting in an ion depletion zone. It was subsequently shown that dendrite formation was reduced by over 98% when 15x the limiting current was forced across the electrodes and acoustic stimulation was delivered. Furthermore, it was shown that compared to the scenario without ultrasonic stimulation, the steady state potential was also reduced by 29%, indicating much better ion exchange between the electrodes. These findings suggest that ultrasonic stimulation can be a tool for enhancing electrochemical processes such as battery charging and discharging.