Electrochemical Charge Transfer Research Articles

In Situ Construction of Bimetallic Selenides Heterogeneous Interface on Oxidation-Stable Ti3C2Tx MXene Toward Lithium Storage with Ultrafast Charge Transfer Kinetics.

Ti3C2Tx (MXene) is widely acknowledged as an excellent substrate for constructing heterogeneous structures with transition metal chalcogenides (TMCs) for boosting the electrochemical performance of lithium-ion storage. However, conventional synthesis strategies inevitably lead to poor electrochemical charge transfer due to Ti3C2Tx-derived TiO2 at the heterogeneous interface between Ti3C2Tx and TMCs. Here, an innovative in situ selenization strategy is proposed to replace the originally generated TiO2 on Ti3C2Tx with metallic TiSe2 interphase, clearing the bottleneck of slow charge transfer barrier caused by MXene oxidation. The construction of bimetallic selenide formed by CoSe2 and TiSe2 generates intrinsic electric fields to guide the fast ion diffusion kinetics in a heterogeneous interface. Additionally, the CoSe2/TiSe2/Ti3C2Tx heterogeneous structure with enhanced structural stability and improved rate performance is confirmed by both experiments and theoretical calculations. The engineered heterogeneous structure exhibits an ultra-high pseudocapacitance contribution (73.1% at 0.1mVs-1), rendering it well-suited to offset the kinetics differences between double-layer materials. The assembled lithium-ion capacitor based on CoSe2/TiSe2/Ti3C2Tx possesses a high energy density and an ultralong life span (89.5% after 10000 times at 2Ag-1). This devised strategy provides a feasible solution for utilizing the performance advantages of MXene substrates in lithium storage with ultrafast charge transfer kinetics.

Electrochemical Charge Transfer Kinetics of Ferrocene in the Light of Different Working Electrodes.

Ferrocene is an accidentally discovered organometallic compound that serves as a crucial redox probe in investigating electrochemical charge transfer dynamics. Besides solution phase studies, ferrocene derivatives are well-explored in molecular thin films, including self-assembled monolayers on various electrodes for understanding on-surface redox behavior, and in molecular electronics, and charge storage applications. Heterogeneous charge transfer is an imperative parameter for efficient charge transport in spin-dependent electrochemistry, photoelectrochemistry, and molecular electronic devices. In this work, we aim to study the electrochemical charge transfer of ferrocene on various electrodes such as commercially obtained glassy carbon, graphite rod, indium tin oxide (ITO), and as-prepared gold, and nickel to determine the impact of the nature of the working electrode on the electron transfer rate, diffusion coefficient, and reversibility of the redox process. Both the direct current and alternating current-based electrochemical experiments are performed, followed by digitization of the experimental results. The kinetics of electron transfer and electrochemical reversibility reveal a strong dependence on the nature of the working electrode, as the electrochemically driven oxidation and reduction of the material of interest are directly related to the Fermi energy and electronic structure of the working electrode.

Effect of Heterojunction Dynamics on Charge Transfer Mechanism in Type-II ZnS/MoS2 Nanocomposite

The development of novel nanocomposites holds immense potential for various applications in optoelectronics, catalysis, energy storage systems and photovoltaic applications. In this manuscript, the synthesis and comprehensive characterization of type-II ZnS/MoS2 nanocomposite synthesized by hydrothermal roue are reported. The synthesized nanocomposite was characterized by numerous analytical techniques to analyse its structural, morphological, optical, and electrochemical properties. XRD analysis revealed the presence of both ZnS and MoS2 phases in the nanocomposite, validating its successful formation. UV-visible spectroscopy (UV) was utilized to study its optical properties which revealed a band gap of 3.2 eV. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging demonstrated the presence of large ZnS sheets with smaller nanoparticles of MoS2 dispersed over the surface, indicating the hierarchical structure of the composites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to evaluate the electrochemical performance and charge transfer dynamics of the nanocomposite. These techniques facilitated the investigation of their suitability for solar cells. CV analysis displayed prominent reduction peaks, indicating the presence of active electrochemical sites in the nanocomposites. Furthermore, it revealed diffusion-controlled behaviour which indicates the potential of the nanocomposite for efficient solar cells. EIS analysis revealed the presence of Warburg diffusion in the Nyquist plot which indicates the possibility of efficient charge transport and ion diffusion within the nanocomposites. This shows the suitability of nanocomposite material for solar cell applications.

(Invited) In Situ x-Ray Diffraction Studies of the Atomic Structure and Charge Distribution at the Electrochemical Interface

The presence of specifically adsorbed anions can significantly affect the electrochemical reactivity of a metal electrode which is of major interest for galvanic deposition, etching, corrosion and electrocatalysis. In-situ surface x-ray diffraction has enabled an atomic/molecular-level understanding of the interface under reactive conditions, including its potential and time dependence, to be developed. While information about the atomic structure of the electrode surface in electrochemical in-situ cells has been widely investigated, insight into the charge distribution and the structure of the electrolyte at the interface is still lacking. Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships.A fundamental understanding of the nature of the charge transfer, especially the influence of the applied potential and the screening by the electrolyte, is a major goal in electrochemistry to better understand electrochemical processes and charge transfer during adsorption and deposition. [1]Thus, combining x-ray spectroscopy and x-ray diffraction to gain site specific information about the charge distribution at buried interfaces is a promising tool. [2,3]Examples of how the use of surface x-ray scattering techniques can help to characterize electrochemical interfaces in-situ in order to link, structure, reactivity and stability will be presented. [4-5] Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships and to understand growth kinetics and electrochemical phase formation.

Eggshell membrane-derived electrocatalysts for water electrolysis

Green H2 (GH2) holds significant promise as a renewable energy resource, particularly in addressing the escalating energy demands sustainably. The imperative for economically viable GH2 technologies, primarily via water electrolysis, has spurred extensive research into suitable electrocatalytic materials. Eggshell membrane (ESM) is typically considered a biowaste material obtained from eggs, which are among the most widely consumed foods both domestically and industrially. Many countries legally require the effective treatment of ESM before disposal to prevent environmental contamination. Therefore, we propose upcycling ESM as an electrocatalytic support, forming transition metal-based active sites through chemical and thermal treatment, followed by doping highly reactive Fe sites electrochemically. ESM’s nanofibrous morphology and porous structure confer catalytic advantages. X-ray photoelectron spectroscopy analysis reveals that certain chemical functional groups in the ESM are involved in the spontaneous electrochemical charge transfer and the adsorption of metal ions, contributing to the formation of metal nanoparticles. Furthermore, various anionic chemical elements such as P, O, N, and S, which originate from intrinsic ESM, can participate in electrocatalysis. The Fe sites electrochemically induced on the Ni and Co nanoparticle surfaces in the ESMs demonstrate excellent electrocatalytic activity and durability toward the oxygen and hydrogen evolution reactions, respectively. This study provides a strategy to utilize ESM as an electrocatalytic material for the development of commercially viable electrocatalysts to produce GH2 by transforming biowaste into value-added materials. Moreover, it promotes the investigation of the (electro)chemical functionalities of biomaterials and the correlation between their functions and electrocatalytic activities.

Phase Engineering of High-Entropy Alloy for Enhanced Electrocatalytic Nitrate Reduction to Ammonia.

Directly electrochemical conversion of nitrate (NO3 -) is an efficient and environmentally friendly technology for ammonia (NH3) production but is challenged by highly selective electrocatalysts. High-entropy alloys (HEAs) with unique properties are attractive materials in catalysis, particularly for multi-step reactions. Herein, we first reported the application of HEA (FeCoNiAlTi) for electrocatalytic NO3 - reduction to NH3 (NRA). The bulk HEA is active for NRA but limited by the unsatisfied NH3 yield of 0.36 mg h-1 cm-2 and Faradaic efficiency (FE) of 82.66 %. Through an effective phase engineering strategy, uniform intermetallic nanoparticles are introduced on the bulk HEA to increase electrochemical active surface area and charge transfer efficiency. The resulting nanostructured HEA (n-HEA) delivers enhanced electrochemical NRA performance in terms of NH3 yield (0.52 mg h-1 cm-2) and FE (95.23 %). Further experimental and theoretical investigations reveal that the multi-active sites (Fe, Co, and Ni) dominated electrocatalysis for NRA over the n-HEA. Notably, the typical Co sites exhibit the lowest energy barrier for NRA with *NH2 to *NH3as the rate-determining step.

Synthesis of clay/Fe/ZSM-5 composite membrane for chromium (vi) removal from aqueous media and its electrochemical performance

The present study explores the potential use of a Clay/Fe/ZSM-5 zeolite membrane as an effective platform for Chromium (VI) filtration. The raw clay sourced from Wadi Haqil Ras Al-Khaimah-UAE was utilized for fabricating the clay support sintered at 1000°C. Clay powder with a granulometry range of 125 µm ≤ Φ ≤ 250 µm, was obtained through crushing and sieving with ASTM sieves and used to prepare the clay support. The Fe/ZSM-5 zeolite was synthesized via the hydrothermal method, using tetrapropylammonium bromide (TPABr) as an organic structure-directing template. The characterization of both the clay support sintered at 1000°C and Fe/ZSM-5 zeolite membrane was conducted through various techniques, including XRD, FTIR, FE-SEM coupled with EDS, and XPS analysis. Notably, the support exhibited a relatively high deionized water flux, stabilizing at 140 L.m−2.h−1 after 120 min of operation, indicating excellent permeability. FE-SEM observations confirmed that Fe/ZSM-5 consisted primarily of granular particles with an orthorhombic crystal lattice, aligning with its crystallinity demonstrated by XRD analysis. The filtration tests for Cr(VI) solutions, conducted using a flow loop designed for cross-flow filtration, demonstrated retention rates of 23 % and 40 % for the clay support and Fe/ZSM-5 zeolite membrane, respectively, after a working time of 120 min. These results suggest the potential of Fe/ZSM-5 zeolite as an effective alternative adsorbent for removing Cr(VI) from wastewater, showcasing outstanding performance in this application. The Clay support and Fe/ZSM-5 zeolite membrane materials were used as electrodes for cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in [Fe(CN)6]3-/4-/0.1 M KCl solution, and Fe/ZSM-5 zeolite membrane material exhibited high electrochemical charge transfer compared to the clay support material.

Phase Engineering of High‐Entropy Alloy for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

Directly electrochemical conversion of nitrate (NO3−) is an efficient and environmentally friendly technology for ammonia (NH3) production but is challenged by highly selective electrocatalysts. High‐entropy alloys (HEAs) with unique properties are attractive materials in catalysis, particularly for multi‐step reactions. Herein, we first reported the application of HEA (FeCoNiAlTi) for electrocatalytic NO3− reduction to NH3 (NRA). The bulk HEA is active for NRA but limited by the unsatisfied NH3 yield of 0.36 mg h−1 cm−2 and Faradaic efficiency (FE) of 82.66%. Through an effective phase engineering strategy, uniform intermetallic nanoparticles are introduced on the bulk HEA to increase electrochemical active surface area and charge transfer efficiency.The resulting nanostructured HEA (n‐HEA) delivers enhanced electrochemical NRA performance in terms of NH3 yield (0.52 mg h−1 cm−2) and FE (95.23%). Further experimental and theoretical investigations reveal that the multi‐active sites (Fe, Co, and Ni) dominated electrocatalysis for NRA over the n‐HEA. Notably, the typical Co sites exhibit the lowest energy barrier for NRA with *NO + H+ + e− → *NOH as the rate‐determining step.

Preparation of a hierarchical porous activated carbon derived from cantaloupe peel/fly ash/PEDOT:PSS composites as Pt-free counter electrodes of dye-sensitized solar cells

Hierarchical porous activated carbon/fly ash/PEDOT:PSS composites (AC:FA) for a counter electrode (CE) were created using a doctor blade technique and applied in dye sensitized solar cells. Hierarchical porous activated carbon (AC) was produced using a potassium hydroxide (KOH) activation process from cantaloupe peels (Cucumis melo L. var. cantaloupensis). AC was introduced into fly ash at various mass ratios to enhance several physical and electrochemical characteristics. Compared to bare FA, the AC:FA electrode displayed a high electrocatalytic activity for the iodide/triiodide redox (I−/I3−) reaction. The test findings show that a higher proportion of AC has an impact on a CE's catalytic activity and charge transfer resistance. The power conversion efficiency (PCE) of the dye-sensitized solar cell (DSSC) attained 5.81 % using the AC:FA CE with AC in a mass ratio of FA in 3:1 (wt./wt.), which is very near the performance of manufactured DSSC's with a platinum (Pt)-based CE (5.91 %). The AC:FA CE stands out as a strong candidate to substitute for costly Pt CEs due to its enhanced electrochemical activity and charge transfer capabilities obtained with an inexpensive and simple production procedure.

External and internal stimuli for enhanced supercapacitor performance

Use of internal and external stimuli can be an alternative tool to address the limitations of a supercapacitor for its enhanced electrochemical properties. Influence of internal stimuli, such as redox active dopants and vacancies, can alter the electronic structure or phase of the electrode material, leading to an improved redox behavior of the pseudo-capacitors by virtue of electron polarizations, leading to a better electrochemical charge transfer kinetics. On the other hand, external stimuli, such as applied magnetic field, can alter the diffusion characteristics of the active ions in the electrolyte, thereby changing the ion/charge rearrangement and ion diffusion characteristics within supercapacitor electrodes. This Perspective emphasizes the importance of these two aspects, supported by an in-depth literature review to give a comprehensive overview of internal and external stimuli effects in designing the model systems for future electrochemical applications.

Insights into charge transfer dynamics of Li batteries through temperature-dependent electrochemical impedance spectroscopy (EIS) utilizing symmetric cell configuration

Studying charge transfer processes in Li batteries poses a challenge due to their complicated nature and the battery's inherent inertness. While electrochemical impedance spectroscopy (EIS) offers a promising approach to investigating these processes, its effectiveness is hindered by the complexity of the data generated and the ambiguity in the analyses. Here, we demonstrate that the assignment process is not straightforward for complex secondary Li batteries, and it necessitates additional measurements and in-depth analysis. We first performed simplification of the impedance data by employing symmetric cell configurations to obtain charge transfer resistance values for each electrode. We second took advantage of altering three parameters during the EIS measurement: electrolyte composition, measurement temperature, and the state of health to extract important parameters related to both the anodic and cathodic charge transfer mechanisms. The analysis enabled the correlation of the observed charge transfer resistances to the corresponding electrochemical process and to obtain the kinetic parameters of the studied process. Our work illustrates how EIS can be used to study and understand the intricate electrochemical charge transfer processes in Li batteries, which are difficult to explore using alternative techniques.

Analysis of the Distribution of Relaxation Times (DRT) Responses of Li-Ion Cells as a Function of Their Preparation Conditions

The distribution of relaxation times (DRT) approach was used to analyze the electrochemical impedance spectra obtained for lithium-ion cells as a function of their state of charge as well as the cell preparation conditions. The cells were made using LiFePO4 cathodes with PEDOT:PSS binder and Li anodes. The following parameters were varied: the load of the active mass with LiFePO4, the presence or absence of carbon nanotubes, the presence or absence of the carbon coating of the current collector, die-pressing of the active mass, as well as artificial degradation of the binder using thermal treatment. The results support the view adopted in the literature that the DRT response of Li-ion cells involves 4 main regions attributed to (i) contact resistance between the particles of the active mass or the particles and the current collector; (ii) ionic resistance of the active layer including that of SEI on the surface of the electrodes; (iii) faradaic resistance of the electrochemical charge transfer at the surface of the active material, and (iv) solid-state diffusion/transport of Li+ ions in the particles of active material. Moreover, we identified yet another contribution to the DRT spectra related to the ionic conductivity of the binder and electrolyte in the active mass of the cathode.

Electrochemical detection of paracetamol using zeolitic imidazolate framework and graphene oxide derived zinc/nitrogen-doped carbon

A composite of zeolitic imidazolate frameworks and graphene oxide (ZIF-GO) derived 3D–2D Zn/N-doped carbon (ZnNC-rGO) was developed for the electrochemical detection of the analgesic paracetamol (PCT). The pyrolysis of ZIF-GO led to the formation of a nanoscale structure featuring ZnNC cubes embedded in rGO sheets. The Zn0-to-ZnO phase transition was found to mediate electrons during the reversible paracetamol redox reactions, which contributed to the sensing current response. Upon 800 °C heating under a N2 atmosphere, the mesoporosity of ZnNC-rGO(800) was significantly enhanced, thereby increasing the electrochemical surface area and charge transfer efficiency. The electrode sensitivity was optimized at a calibration linearity of 0.526 μA μM−1) with detection limit (0.077 μM) in the range of 0.5 – 70 μM using differential pulse voltammetry mode (DPV). The precision of analytical recovery for trace paracetamol concentrations was maintained based on the excellent reproducibility and selectivity trials in the presence of interference chemicals and in real water samples.

A Comparative Study of the Corrosion Behavior of P110 Casing Steel in Simulated Concrete Liquid Containing Chloride and Annulus Fluid from an Oil Well

The corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid was investigated to reveal the corrosion pattern and protective properties of corrosion products in the two environments. Potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), Mott–Schottky tests, and electrochemical noise (EN) tests were used to study the corrosion behavior of P110 casing steel in simulated concrete liquid and simulated annulus fluid saturated with CO2. Scanning electron microscopy (SEM) combined with Energy-Dispersive Spectrometer (EDS) mapping was used to characterize the corrosion morphology and elemental distribution of P110 casing steel. The results show that the corrosion resistance of P110 casing steel deteriorates with the increasing immersion days in the simulated annulus fluid, the impedance decreases gradually, and the corrosion-product film shows a loose and porous structure. In the simulated concrete liquid, under the condition of containing a low concentration of Cl−, the protection of the corrosion products gradually increases with the extension of immersion days. With the increasing concentration of Cl− and the extension of immersion days, the electrochemical noise resistance and charge transfer resistance of P110 steel decrease gradually, and the protective property of the corrosion-product film decreases, which is capable of forming steady pitting corrosion.

Pillar[5]arene functionalized Au NPs and BiOX (Cl/Br/I) heterojunction constructed the enhanced photo-electrochemical sensor for ultrasensitive detection of serotonin

The functional photoelectric materials based on bismuth oxyhalides (BiOX, X = Cl, Br and I) have been widely used in the field of photo-electrochemistry (PEC) due to their excellent physical, chemical and optical properties. Herein, a series of BiOX nanoflowers conjugated water-soluble pillar[5]arenes functionalized Au (Au@WP5/BiOX) modified PEC sensor are constructed and investigated for the PEC detection of serotonin. Upon exploring the physical properties, such as size, visible light absorption capacity, band gap and impedance, of the three BiOX materials, it is discovered that BiOBr is more effective in detecting 5-HT due to its high redox ability, moderate band gap (∼2.03 eV), and low impedance. BiOBr can provide a high and stable starting photocurrent compared to the other two bismuth oxyhalides. When used in acidic or neutral environments, 5-HT with a positive charge can undergo electrostatic adsorption and host-guest complexation behavior with WP5, which has a negative charge. By using WP5, the recognition ability of the material to 5-HT molecules can be enhanced, and the adsorption of 5-HT molecules on Au@WP5/BiOBr can be accelerated. The local surface plasmon resonance effect (LSPR) of gold nanoparticles (Au NPs) can accelerate the electrochemical reaction rate and charge transfer rate, which ultimately leads to the amplification of the photocurrent signal. As a result, the 5-HT detection sensor based on Au@WP5/BiOBr has a wide detection range from 0.01 to 100 μM and a low detection limit of 3 nM (S/N = 3) compared to other sensors, including Au@WP5/BiOCl and Au@WP5/BiOI. The proposed PEC sensor also exhibits good stability and selectivity, making it a promising strategy for detecting biological small molecules using pillar[5]arene functionalized PEC active materials.

Highly Porous Metal-Organic Framework Entrapped by Cobalt Telluride-Manganese Telluride as an Efficient Bifunctional Electrocatalyst.

The electrochemical conversion of oxygen holds great promise in the development of sustainable energy for various applications, such as water electrolysis, regenerative fuel cells, and rechargeable metal-air batteries. Oxygen electrocatalysts are needed that are both highly efficient and affordable, since they can serve as alternatives to costly precious-metal-based catalysts. This aspect is particularly significant for their practical implementation on a large scale in the future. Herein, highly porous polyhedron-entrapped metal-organic framework (MOF)-assisted CoTe2/MnTe2 heterostructure one-dimensional nanorods were initially synthesized using a simple hydrothermal strategy and then transformed into ZIF-67 followed by tellurization which was used as a bifunctional electrocatalyst for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The designed MOF CoTe2/MnTe2 nanorod electrocatalyst exhibited superior activity for both OER (η = 220 mV@ 10 mA cm-2) and ORR (E1/2 = 0.81 V vs RHE) and outstanding stability. The exceptional achievement could be primarily credited to the porous structure, interconnected designs, and deliberately created deficiencies that enhanced the electrocatalytic activity for the OER/ORR. This improvement was predominantly due to the enhanced electrochemical surface area and charge transfer inherent in the materials. Therefore, this simple and cost-effective method can be used to produce highly active bifunctional oxygen electrocatalysts.

New natural dyes extracted by ultrasonic and soxhlet method: Effect on dye-sensitized solar cell photovoltaic performance

This study employed soxhlet and ultrasonic methods to extract novel natural dyes from Rhamnus tinctoria seed, Rubia fruticosa fruits, and Pinus pinea bark, which were then used as sensitizers in dye-sensitized solar cells (DSSCs). XRD data showed that TiO2 in the photoanode layer was in the anatase phase. The produced DSSCs were assessed for photovoltaic performance and electrochemical charge transfer while sensitizing dyes were characterized using UV–vis spectroscopy and FTIR. Natural dyes leached with different extraction methods showed different absorption behaviors in the UV–vis region. FTIR results revealed the presence of both carbonyl and hydroxyl groups, which enhanced the interaction between the extracted dyes and the TiO2 thin film. All cells using sensitizers obtained by the Soxhlet method showed higher efficiency compared to the ultrasonic method. The highest cell performance (ɳ = 0.47%) was obtained with 0.71 V Voc, 0.92 mA/cm2 Jsc, and 0.72 FF for the sensitizer extracted from Rhamnus tinctoria seeds by the soxhlet method.

Understanding electrochemical interfaces through comparing experimental and computational charge density-potential curves.

Electrode-electrolyte interfaces play a decisive role in electrochemical charge accumulation and transfer processes. Theoretical modelling of these interfaces is critical to decipher the microscopic details of such phenomena. Different force field-based molecular dynamics protocols are compared here in a view to connect calculated and experimental charge density-potential relationships. Platinum-aqueous electrolyte interfaces are taken as a model. The potential of using experimental charge density-potential curves to transform cell voltage into electrode potential in force-field molecular dynamics simulations, and the need for that purpose of developing simulation protocols that can accurately calculate the double-layer capacitance, are discussed.

Pseudouridine-modified RNA probe for label-free electrochemical detection of nucleic acids on 2D MoS2 nanosheets.

RNA modification, particularly pseudouridine (Ψ), has played an important role in the development of the mRNA-based COVID-19 vaccine. This is because Ψ enhances RNA stability against nuclease activity and decreases the anti-RNA immune response. Ψ also provides structural flexibility to RNA by enhancing base stacking compared with canonical nucleobases. In this report, we demonstrate the first application of pseudouridine-modified RNA as a probe (Ψ-RNA) for label-free nucleic acid biosensing. It is known that MoS2 has a differential affinity for nucleic acids, which may be translated into a unique electronic signal. Herein, the Ψ-RNA probe interacts with the pristine MoS2 surface and causes a change in interfacial electrochemical charge transfer in the MoS2 nanosheets. Compared with an unmodified RNA probe, Ψ-RNA exhibited faster adsorption and higher affinity for MoS2. Moreover, Ψ-RNA could bind to complementary RNA and DNA targets with almost equal affinity when engaged with the MoS2 surface. Ψ-RNA maintained robust interactions with the MoS2 surface following the hybridization event, perhaps through its extra amino group. The detection sensitivity of the Ψ-RNA/MoS2 platform was as low as 500 attomoles, while the results also indicate that the probe can distinguish between complementary targets, single mismatches, and non-complementary nucleic acid sequences with statistical significance. This proof-of-concept study shows that the Ψ-RNA probe may solve numerous problems of adsorption-based biosensing platforms due to its stability and structural flexibility.

Understanding the Effect of Mechanical Degradation on the Performance of Solid-State Batteries through Particle Simulations

All-solid-state batteries (ASSBs) have garnered significant interest as a promising alternative to conventional lithium-ion batteries, offering improved safety, higher energy density, longer lifespan, faster charging and wider operating temperature range. A key advantage of ASSBs is the use of solid electrolytes (SE), which eliminate the risks associated with flammable liquid electrolytes. However, the complex electrochemical behavior and multi-scale nature of ASSBs pose challenges in designing and optimizing their performance. This study employs Discrete Element Method (DEM) particle-based models to better understand degradation behavior of ASSBs by considering electrochemical reaction, mass and charge transfer, intercalation expansion and material deformationOur simulations were developed in MATLAB and were performed on a half-cell configuration comprising a SE-layer and an anode electrode. The anode electrode was composed of a particle mixture containing active material (AM) and SE. In our simulations, Si was employed as AM, which experiences substantial intercalation expansion during charge cycling 1. Our previously developed DEM model2,3 resolved elastic and plastic deformation of both AM and SE particles which become compressed due to the intercalation expansion. The simulation of intercalation was achieved by integrating the Newman electrochemical model,4 into the DEM mechanical model. Building on our earlier study5, where the Li concentration was resolved within each AM particle, this study is also accounting for the Li-ion potential within each SE particle. Interparticle conduction and diffusion were computed by determining the contact area of AM-AM and SE-SE contacts, which were affected by the compression of the electrode. The electrochemical reaction was calculated at the AM-SE interface using the Butler-Volmer equation, and in addition the influence of compressive stress on the reaction6 was included.Figure 1(a) depicts the Li concentration and Li-ion potential distribution within the half-cell during charging at different states of charge (SOC), while Figure 1(b) provides a 3D view of the distributions at a SOC of 50%. A considerable expansion of the Si anode is evident. The gradients of Li concentration and Li-ion potential signify significant mass and charge transfer resistance during the charging process. Comparing the distribution of the particles, the anode becomes more porous after the first cycle for the same value of SOC. This effect is attributed to the extensive expansion of the Si anode, leading to plastic compression of the SE layer, which becomes more compact after each cycle. The growing porosity diminishes the contact area between particles, ultimately resulting in the degradation of the half-cell's capacity. In addition to SE-layer compaction, this study aims to investigate several degradation mechanisms and their impact on the performance of ASSBs, including the development of shell voids resulting from AM-SE delamination, crack propagation through SE, and fragmentation of AM.The results of this study provide valuable insights into understanding the effect of mechanical degradation on the performance of ASSBs. By improving our understanding of these mechanisms, we can work towards enhancing the durability and lifespan of ASSBs, ultimately contributing to the development of next-generation energy storage systems. Acknowledgment This work was supported by JSPS KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas, “Science on Interfacial Ion Dynamics for Solid State Ionics Devices, Computational & Data Science” (Gp-A03, grant number 19H05815); and MEXT “Program for Promoting Researches on the Supercomputer Fugaku” (Fugaku battery & Fuel Cell Project), grant number JPMXP1020200301. References M. N. Obrovac and L. Christensen, Electrochem. Solid-State Lett., 7, A93 (2004).M. So, G. Inoue, R. Hirate, K. Nunoshita, S. Ishikawa, and Y. Tsuge, J. Electrochem. Soc., 168, 030538 (2021).M. So, G. Inoue, R. Hirate, K. Nunoshita, S. Ishikawa, and Y. Tsuge, Journal of Power Sources, 508, 230344 (2021).J. Newman and K. E. Thomas-Alyea, Electrochemical Systems, 3rd edition., p. 672, Wiley-Interscience, Hoboken, N.J, (2004).M. So, S. Yano, A. Permatasari, T. D. Pham, K. Park, and G. Inoue, Journal of Power Sources, 546, 231956 (2022).G. Bucci, T. Swamy, S. Bishop, B. W. Sheldon, Y.-M. Chiang, and W. C. Carter, J. Electrochem. Soc., 164, A645 (2017). Figure 1