Electrochemical Characterization Research Articles

Electrical, optical, and structural studies of lithium tungstate-based-phosphate glasses and glass-ceramics

Cathode and electrolyte materials are key components of Li-ion batteries, which influence the safety and electrochemical characteristics. This study focuses on the development and characterization of glassy and glass–ceramic showing either ionic or mixed ionic-electronic conductivity, that can be used as electrolytes or cathodes, respectively, in energy storage devices. Homogenous glasses within the (30 + x)Li2WO4–(70-x)(45.5Li2O–54.5P2O5) system are produced using the melt quenching technique. Structural characterization via XRD and IR spectroscopy revealed diverse structural units. UV–visible absorption studies evaluated optical properties, while impedance spectroscopy measured electrical conductivity. Li2WO4 addition increased density, molar volume, and microhardness. Enhanced electrical conductivity was observed, notably reaching 3.22 × 10−6 (Ω−1 cm−1) at room temperature and 3.13 × 10−5 (Ω−1 cm−1) at 423 K. The richer Li2WO4 materials exhibited ionic conductivity associated to lower activation energy around 0.20 eV. Conductivity’s frequency dependency analysis suggested a correlated barrier hopping mechanism.

Electrooxidation of gaseous volatile organic compounds based on deep eutectic solvent modified Ni/SnOx-Sb nanocomposites

Volatile organic compounds (VOCs) are one of the main sources of atmospheric haze and pose a threat to human health. Electrocatalysis is a technique that catalyzes chemical reactions by applying an electrical potential, which offers mild reaction conditions and environmental friendliness, making it highly promising for the treatment of VOCs. In this research, a series of deep eutectic solvent (DES) modified Ni/SnOx nanosheets doped with different Sb doping amounts (Ni/SnOx-Sb-DES) have been prepared and applied to the electrooxidation of toluene. In the process of electrochemical gas–solid interface catalysis, the content of reactive oxygen species released on Ni/SnOx-Sb-DES electrodes are affected by the specific surface area and the number of oxygen vacancies. Electrochemical characterization discovered that there are significant differences in overpotential among catalysts of different ratios, thus affecting catalytic activity of Ni/SnOx-Sb-DES. Among them, the Ni/SnOx-Sb-DES with best ratio removal rate of toluene reached 83.07%, while the selectivity of CO2 was greater than 95%. This study proposes a method for removing VOCs at ambient temperatures, aiming to provide a new avenue for commercial applications in environmental-related fields.

Modeling solid-state reaction processes: application for the archaeometric study of potteries from Venus Fisica Temple in Pompeii (Italy)

AbstractThis research employs the voltammetry of immobilized microparticles (VIMP) methodology to analyze a collection of ceramic samples from the temple of Venus Fisica in the archaeological site of Pompeii. The primary objective is to discern their origins and manufacturing processes by the solid-state analysis of the electroactive properties of iron minerals, particularly hematite, extensively investigated for its electrochemical and catalytic characteristics. In our study, we propose a model to elucidate the electrochemical processes involved, building upon prior logistic and nucleation formulations. In this model, we consider the possibility of two superimposed pathways. This approach provides a nuanced understanding of composition changes and mineral crystallinity, factors that can induce significant variations in the voltammetric signal. Consequently, it becomes an effective means to discriminate between different provenances and manufacturing techniques of different potteries. The outcomes of this research contribute valuable insights into the intricate realm of ancient ceramic materials, casting light on their origins and production processes within the historical context of Pompeii.

Origins of non-ideal behaviour in voltammetric analysis of redox-active monolayers.

Disorder in redox-active monolayers convolutes electrochemical characterization. This disorder can come from pinhole defects, loose packing, heterogeneous distribution of redox-active headgroups, and lateral interactions between immobilized redox-active molecules. Identifying the source of non-ideal behaviour in cyclic voltammograms can be challenging as different types of disorder often cause similar non-ideal cyclic voltammetry behaviour such as peak broadening, large peak-to-peak separation, peak asymmetry and multiple peaks for single redox processes. This Review provides an overview of ideal voltammetric behaviour for redox-active monolayers, common manifestations of disorder on voltammetric responses, common experimental parameters that can be varied to interrogate sources of disorder, and finally, examples of different types of disorder and how they impact electrochemical responses.

Electrical and electrochemical characterization of FeCo2O4 nanoflakes for flexible supercapacitor applications

Electrical and electrochemical characterization of FeCo2O4 nanoflakes for flexible supercapacitor applications

Impact of Air-Cathodes on Operational Stability of Single-Chamber Microbial Fuel Cell Biosensors for Wastewater Monitoring

The increasing global water pollution leads to the need for urgent development of rapid and accurate water quality monitoring methods. Microbial fuel cells (MFCs) have emerged as real-time biosensors for biochemical oxygen demand (BOD), but they grapple with several challenges, including issues related to reproducibility, operational stability, and cost-effectiveness. These challenges are substantially shaped by the selection of an appropriate air-breathing cathode. Previous studies indicated a critical influence of the cathode on both the enduring electrochemical performance of MFCs and the taxonomic diversity at the electroactive anode. However, the effect of different gas diffusion electrodes (GDE) on 3D-printed single-chamber MFCs for BOD biosensing application and its effect on the bioelectroactive anode was not investigated before. Our study focuses on comparing GDE cathode materials to enhance MFC performance for precise and rapid BOD analysis in wastewater. We examined for over 120 days two Pt-coated air-breathing cathodes with distinct carbonaceous gas diffusion layers (GDLs) and catalyst layers (CLs): cost-effective carbon paper (CP) with hand-coated CL and more expensive woven carbon cloth (CC) with CL pre-applied by the supplier. The results show significant differences in electrochemical characteristics and anodic biofilm composition between MFCs with CP and CC GDE cathodes. CP-MFCs exhibited lower sensitivity (16.6 C L mg−1 m−2) and a narrower dynamic range (25 to 600 mg L−1), attributed to biofouling-related degradation of the GDE. In contrast, CC-MFCs demonstrated superior performance with higher sensitivity (37.6 C L mg−1 m−2) and a broader dynamic range (25 to 800 mg L−1). In conclusion, our study underscores the pivotal role of cathode selection in 3D-printed MFC biosensors, influencing anodic biofilm enrichment time and overall BOD assessment performance. We recommend the use of cost-effective CP GDL with hand-coated CL for short-term MFC biosensor applications, while advocating for CC GDL supplied with CL as the preferred choice for long-term sensing implementations with enduring reliability.

Preparation and characterization of ion-exchanged Ni-Na-β”-Al2O3 and Fe-Na-β”-Al2O3 solid electrolytes for applications in liquid metals

Accurate determinations of the thermochemical properties for the steel alloying elements (Fe, Cr, Ni, Co and Mn) dissolved as corrosion product impurities in Pb and Pb–Bi alloy (LBE) are relevant for the development of Lead-Cooled Fast Nuclear Reactors (LFRs). Ion-selective solid electrolytes are suitable for an electrochemical characterization of the dissolved impurities. Among these, ion-exchanged Ni-β”-Al2O3 and Fe-β”-Al2O3 are promising solid electrolytes for the selective detection of Ni and Fe dissolved in HLMs. In the present works we proposed a preliminary test of liquid and vapor ion-exchanges on commercial polycrystalline Na-β”-Al2O3 tubes at different conditions of temperature and reaction time with NiCl2 and FeCl2 salts, characterizing the effects on the material microstructure. The resulting Ni-Na-β”-Al2O3 and Fe-Na-β”-Al2O3 samples were only partially replaced by nickel or iron, extremely porous, damaged by molten salt corrosion, and contaminated by residual chlorides. When tested as selective sensors in molten LBE, they failed in detecting dissolved nickel or iron. Thus, ion-exchange procedure on polycrystalline Na-β”-Al2O3 substrates still needs to be improved by properly combining the liquid and vapor ion-exchange with optimized reaction conditions in order to increase the sodium replacement yield. Alternatively, efforts may be focused on the preparation and application of other different nickel and iron solid electrolytes.

An Evaluation of the Corrosion Inhibition Performance of Chitosan Modified by Quaternary Ammonium Salt for Carbon Steel in Stone Processing Wastewater

Chitosan was used as the raw material. A quaternization reaction was carried out between 2,3-epoxypropyltrimethylammonium chloride and water-soluble chitosan to prepare quaternary ammonium salt water-soluble chitosan (QWSC), and its corrosion inhibition performance against the corrosion of carbon steel in stone processing wastewater was evaluated. The corrosion inhibition efficiencies of QWSC on carbon steel in stone processing wastewater were investigated through weight loss, as well as electrochemical and surface morphology characterization techniques. The results show that QWSC has superior corrosion inhibition performance for A3 carbon steel. When an amount of 60 mL·L−1 is added, the corrosion inhibition efficiency can reach 59.51%. Electrochemical research has shown that a QWSC inhibitor is a mixed-type corrosion inhibitor. The inhibition mechanisms of the QWSC inhibitor revealed that the positive charge on the surface of carbon steel in stone wastewater was conducive to the adsorption of Cl− in the medium, which produced an excessive negative charge on the metal’s surface. At the same time, the quaternary ammonium cation and amino cation formed in QWSC in stone processing wastewater can be physically absorbed on the surface of A3 carbon steel, forming a thin-film inhibitor to prevent metal corrosion.

Experimentally validating sabatier plot by molecular level microenvironment customization for oxygen electroreduction

Microenvironmental modifications on metal sites are crucial to tune oxygen reduction catalytic behavior and decrypt intrinsic mechanism, whereas the stochastic properties of traditional pyrolyzed single-atom catalysts induce vague recognition on structure-reactivity relations. Herein, we report a theoretical descriptor relying on binding energies of oxygen adsorbates and directly associating the derived Sabatier volcano plot with calculated overpotential to forecast catalytic efficiency of cobalt porphyrin. This Sabatier volcano plot instructs that electron-withdrawing substituents mitigate the over-strong *OH intermediate adsorption by virtue of the decreased proportion of electrons in bonding orbital. To experimentally validate this speculation, we implement a secondary sphere microenvironment customization strategy on cobalt porphyrin-based polymer nanocomposite analogs. Systematic X-ray spectroscopic and in situ electrochemical characterizations capture the pronounced accessible active site density and the fast interfacial/outward charge migration kinetics contributions for the optimal carboxyl group-substituted catalyst. This work offers ample strategies for designing single-atom catalysts with well-managed microenvironment under the guidance of Sabatier volcano map.

Development of conductive carbon-based interdigitated electrode array integrated with microfluidic channel for blood glucose sensing

Purpose This study aims to provide a microfluidic blood glucose sensing platform based on integrated interdigitated electrode arrays (IDEAs) on a flexible quartz glass substrate, adhering closely to pertinent electrochemical characterizations. Design/methodology/approach Sensors are the key elements of the modern electronics era through which all the possible physical quantities can be detected and converted into their equivalent electrical form and processed further. But to make the sensing environment better, various types of innovative architectures are being developed nowadays and among them interdigitated electrodes are quite remarkable in terms of their sensing capability. They are a well-qualified candidate in the field of gas sensing and biosensing, but even their sensitivities are getting saturated due to their physical dimensions. Most of the thin film IDEAs fabricated by conventional optical lithographic techniques do not possess a high surface-to-volume ratio to detect the target specified and that reduces their sensitivity factor. In this context, a classic conductive carbon-based highly sensitive three dimensional (3D) IDEA-enabled biosensing system has been conceived on a transparent and flexible substrate to measure the amount of glucose concentration present in human blood. 3D IDEA possesses a way better capacitive sensing behavior compared to conventional thin film microcapacitive electrodes. To transmit the target biological analyte sample property for the detection purpose to the interdigitated array-based sensing platform, the design of a microfluidic channel is initiated on the same substrate. The complex 3D Inter Digital array structure improves the overall capacitance of the entire sensing platform and the reactive surface area as well. The manufactured integrated device displays a decent value of sensitivity in the order of 5.6 µA mM−1 cm−2. Findings Development of a low-cost array-based integrated and highly flexible microfluidic biochip to extract the quantity of glucose present in human blood. Originality/value Potential future research opportunities in the realm of integrated miniaturized, low-cost smart biosensing systems may arise from this study.

Dimensionality Control of Li Transport by MOFs Based Quasi‐Solid to Solid Electrolyte (Q‐SSEs) for Li−Metal Batteries

AbstractNowadays, lithium‐ion batteries (LIBs) are widely used in all walks of life and play a very important role. As complex systems composed of multiple materials with diverse chemical compositions, where different electrochemical reactions take place, battery interfaces are essential for determining the operation, performance, durability and safety of the battery. This work, set out to study the incorporation of lithium bis(fluorosulfonyl)amide (LiFSI) doped 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][TFSI]) ionic liquid into an archetype Ti‐based Metal Organic Framework (MOF) ((Ti) MIL125−NH2) to create a solid to quasi‐solid (depending on the amount of IL in the system), and how it affects not only ionic transport but also the structural properties of the IL/MOF electrolyte. Remarkably high ionic conductivity values (2.13×10−3 S ⋅ cm−1 at room temperature) as well as a lithium transference number (tLi=0.58) were achieved, supported by pulsed field gradient (PFG) NMR experiments. Electrochemical characterization revealed reversible plating‐stripping of lithium and lower overpotential after 750 h at 50 °C. Additionally, a proof‐of‐concept solid state battery was fabricated resulting in a discharge capacity of 160 mAh ⋅ g−1 at 50 °C and 0.1 C rate after 50 cycles. This work presents a suitable strategy to dendrite suppression capability, allowing its implementation as interface modifiers in next‐generation solid‐state batteries.

Effect of Presodiation Additive on Structural and Interfacial Stability of Hard Carbon | P2‐Na0.66Mn0.75Ni0.2Mg0.05O2 Full Cell

The compatibility between a corncob‐derived hard carbon anode and a layered oxide cathode (Na0.66Mn0.75Ni0.2Mg0.05O2), as well as the effect of presodiation via cathode additive (Na2C4O4), are investigated in a sodium‐ion full cell. Extensive physicochemical and electrochemical characterizations are performed to deeply investigate the structural and interfacial evolution of the materials in the presodiated cell, either within the single cycle or upon long‐term cycling. The use of sacrificial cathode additives is generally regarded as a method to improve full cell performance, especially when using sodium‐deficient materials. However, undesired effects upon decomposition of the sacrificial salt may arise due to the complexity of the system. In this study, it is evidenced that the presodiation changes the properties of the electrodes causing a worsening of the electrochemical performance of the cell during long‐term cycling. The surface morphology of the cathode is negatively affected by the formation of holes/cracks, while redox processes associated with structural transformations are suppressed in the voltage window of interest, with partial structural deformations occurring during activation cycles. The SEI and CEI are also affected by the formation of insulating organic species, which lead to an increased thickness and interphase resistance hampering the charge transfer kinetics of the cell.

Influence of Cathode Calendering Density on the Cycling Stability of Li-Ion Batteries Using NMC811 Single or Poly Crystalline Particles

Abstract Calendering of battery electrodes is a commonly used manufacturing process that enhances electrode packing density and therefore improves the volumetric energy density. While calendering is standard industrial practice, it is known to crack cathode particles, thereby increasing the electrode surface area. The latter is particularly problematic for new Ni-rich layered transition metal oxide cathodes, such as NMC811, which are known to have substantial surface-driven degradation processes. To establish appropriate calendering practices for these new cathode materials, we conducted a comparative analysis of uncalendered electrodes with electrodes that have a 35% porosity and 25% for single crystal and polycrystalline NMC811. PC cathodes show clear signs of cracking and decrease in rate capability when calendered to 25% porosity, whereas SC cathodes, achieve better cycling stability and no penalty in rate performance at these high packing densities. These findings suggest that SC cathodes should be calendered more densely, we provide a comprehensive overview of both electrochemical and material characterisation methods that corroborate why PC and SC electrodes show such different degradation behaviour. Overall, this work is important because it shows how new single-crystal cathode materials can offer additional advantages in terms of rate performance and cycling stability by calendaring them more densely

Investigation of current density and temperature distribution characteristics under transient conditions based on a 108 cm2 segmented proton exchange membrane fuel cell

Visualizing the electrochemical and temperature distribution characteristics inside proton exchange membrane fuel cell (PEMFC) should greatly contribute to the product development and performance optimization. In the study, a customized 27-segment 108 cm2 fuel cell was fabricated based on the printed circuit board methodology to achieve the local current density and local voltage measurement. In addition, 27 thermocouples were embedded in the segmented cathode graphite gas flow plate for local temperature measurement. Detailed information of fuel cell core components, multi-channel data acquisition system, external temperature control system, and uncertainty analysis was presented. According to the test results of 4000 s current rising conditions and 2400 s current decreasing conditions, the measurement deviation of total current between data acquisition system and TOYO test station is 2.4%–3.2%. Meanwhile, the deviation of output voltage ranges from 0.1% to 2.6%. To quantify the degree of distribution non-uniformity, the range and standard deviation of local parameter values as well as contour map are demonstrated. The non-uniformity of local current density and local temperature becomes more significant under higher operating current conditions. Furthermore, the degree of parameter non-uniformity is more noticeable under current rising conditions compared with current decreasing conditions. The transient increase of operating current leads to the sudden overshoot phenomena of local current range, and the change of local current density among all segments is instantaneously finished. However, the range of current demonstrates relatively smooth transition trends when reactant flow rate rises. Higher temperature area appears in the middle of membrane electrode assembly, especially in the position with higher local current density. The parameter distribution and transition characteristics could provide helpful guidance for fuel cell optimization and diagnosis.

A Solid‐Solution with Asymmetric Ni‐O‐Cr Sites for Boosting Protonation toward Anodic Oxidation

AbstractReplacing the slow protonation process of oxygen evolution reaction (OER) with the fast protonation of alcohol electro‐oxidation can decrease the driving potentials, thus improving overall efficiency of electrochemical devices. However, the formation of effective catalytic sites for alcohol oxidation remains challenging in accelerating protonation to inhibit metal leaching and improve catalyst stability. Herein, asymmetric Ni‐O‐Cr sites are constructed by alloying Cr into the NiO matrix to optimize coordination environments, showing significantly enhanced stability during alcohol electro‐oxidation. The asymmetric Ni‐O‐Cr can maintain constant valence states of Cr and Ni during alcohol oxidation, efficiently suppressing metal dissolution even at high oxidation potentials. In situ electrochemical characterizations combined with theoretical calculations indicate that asymmetric Ni‐O‐Cr can improve adsorption and activation of OH* and alcohol molecules compared to pure NiO, thus increasing anodic kinetics. The theoretical results also indicate that the smaller gap of Ni 3d‐O 2p in asymmetric Ni‐O‐Cr strengthens charge transfer, leading to fast protonation of catalytic sites with enhanced stability. This work gives insights into boosting anodic protonation using asymmetric sites‐enriched solid‐solution electrocatalysts.

Exploring Selenide Synthesis Pathways for Optimizing Energy Conversion

This study investigated the structural and electrochemical characteristics of binary and quaternary systems comprising nickel, cobalt, and iron selenides. The powders were obtained via a solvothermal route. X-ray diffraction (XRD) and Raman spectroscopy revealed significant phase diversity. It was observed that increasing the proportion of d-block metals in quaternary systems enhances structural entropy, potentially leading to more homogeneous and stable structures dominated by energetically preferred components such as nickel. The electrochemical analysis indicated that the binary system exhibited a reversible redox reaction, with nickel selenide-based samples demonstrating the highest electrochemically active surface area. Quaternary systems display varying degrees of electrochemical stability. An equal contribution of nickel, cobalt, and iron appears beneficial in achieving stable electrodes. This research contributes to understanding the relationship between transition metal selenides’ structural, morphological, and electrochemical properties, providing insights into their potential applications in hydrogen generation.

Improved Reversibility of Thin-Film Solid Oxide Cells at 500 °C by Tailoring Sputtering Processes for Depositing Yttria-Stabilized Zirconia Electrolyte.

The present study investigates the impact of sputtering configurations on the microstructure and crystallinity of thin-film yttria-stabilized zirconia electrolytes for anodized aluminum oxide-supported all-sputtered thin-film reversible solid oxide cells. Employing various sputtering parameters, such as target-substrate distance and substrate rotation speed, the present study reveals distinct surface characteristics and crystalline structures of thin-film yttria-stabilized zirconia. The microstructure analysis includes scanning electron microscopy and atomic force microscopy examinations, uncovering the influence of the process parameters on the surface morphology, roughness, and grain size. X-ray diffraction data illustrate the texture preferences and crystallite characteristics. The electrochemical characterization of the reversible solid oxide cells demonstrates that the optimized sputtering configuration significantly outperforms the others in both SOFC and SOEC modes, showing exceptional current densities of 964 mA/cm2 at 1.3 V in electrolysis mode at 500 °C. Electrochemical impedance spectroscopy further reveals improved charge transfer reactions at the interface of the electrolyte. The enhanced electrochemical performance is attributed to the unique microstructure and crystallinity of the thin film of yttria-stabilized zirconia. The record-breaking electrolysis performance of this work at 500 °C underscores the potential of tailored sputtering parameters in optimizing the reversible solid oxide cell performance.

Hierarchical nanostructured Co0.5Mn0.5WO4 efficient electrode material for asymmetric supercapacitor application

BackgroundThis research focuses on the electrochemical characteristics of binary metal tungstates for asymmetric supercapacitor applications. Metal tungstates such as Cobalt tungstate (CoWO4) and Manganese tungstate (MnWO4) exhibit excellent electrical conductivity and redox characteristics. Different combinations of binary metal tungstates can serve as effective electrode materials for supercapacitor applications. MethodHerein, Co0.5Mn0.5WO4 nanoparticles was synthesized by the co-precipitation method followed by calcination. The prepared nanoparticles was used as an electrode material for the supercapacitor application. For study the two electrode system, Co0.5Mn0.5WO4 and activated carbon were worked as anode and cathode electrode, respectively. Significant findingsThe prepared electrode materials exhibit a battery type pusudocapacitance in cyclic voltammetry (CV). The charging and discharging properties of the material was analysed by galvanic charging and discharging (GCD) studies and it displays the specific capacitance value of 444 F/g at the current density of 1 A/g and it shows the specific capacitance retention of 91% after 1500 cycles. AC//Co0.5Mn0.5WO4 ASC device shows good energy density, power density and specific capacitance values of 30.5 Wh/Kg, 2800 W/Kg and 112 F/g at 1 A/g current density, respectively.

Stability of passive film and pitting susceptibility of 316 L stainless steel in the aggressive oilfield environment containing Cl−-CO2-O2

In this paper, the effects of chloride ions, oxygen, and carbon dioxide on the corrosion resistance of passive films formed on 316 L stainless steel were investigated in the aggressive oilfield environment using electrochemical testing and microscopic characterization techniques. The results showed that Cl− accelerated the anodic dissolution of the metal and compromised the structure and densification of the passive film, thus reducing its corrosion resistance. An increase in the partial pressure of carbon dioxide initially promotes pitting, but subsequently inhibited further corrosion development. The presence of oxygen enhanced the cathodic reaction and passive film formation, effectively preventing the invasion of aggressive chloride ions, thus inhibiting further corrosion. These findings provide a significant scientific basis for material selection and protection of oil extraction equipment in oilfield environments.

Gluconic acid as the supplementary additive realizing high-efficiency production of metal manganese with decreased dosage of toxic selenium dioxide

Minimizing the dosage of toxic SeO2 additive in electrolyte for electrochemical deposition of metal manganese without compromising the current efficiency has long been the desire for electrolytic manganese industry. Herein, by combinative usage of SeO2 and gluconic acid (GlcA) as the composite additives, 50 % of SeO2 dosage can be cut down while the current efficiency can be increased from 67 % to 90 % at the same time, realizing the energy consumption being reduced by 23 % at the optimized concentration of 1.84 g/L GlcA. The electrochemical tests and electrode surface characterizations as well as density functional theory calculations jointly imply that the addition of GlcA can greatly increase the diffusion coefficient of Mn2+ from 1.5 × 10−6 cm2/s to 5.6 × 10−5 cm2/s, accelerating the approaching of Mn2+ towards the electrode surface by decreasing the diffusion barrier energy from 17.93 kJ/mol to 11.51 kJ/mol. On the electrode surface, the SeO32− is responsible for facilitating the electrochemical deposition of metal Mn by forming the MnSe intermediate while GlcA is in charge of restraining the activation of H2O molecule for inhibiting H2 generation, synergistically contributing to the efficient production of electrolytic metal manganese. The results can provide new insights for the environmentally friendly and high-efficiency upgrading of manganese industry.