Electrochemical Society Research Articles

From cells to cars: Developing an electrochemical techniques and diagnostics course for new battery engineers

We are a team of three battery researchers and engineers who are working with The Electrochemical Society to develop an "electrochemical techniques and diagnostics for batteries" curriculum, comprised of an online course and an in-person workshop. With a combined 40+ years of experience working in battery research and engineering, ranging from academia to electric vehicle manufacturing, we have noticed that there exists a gap in applied electrochemistry knowledge needed to train the rapidly expanding workforce of battery engineers and scientists. In this backstory, we explain the origin story of our team, our motivations for developing the course and the things we have learned in working together. We share our insights into the emerging electric vehicles business and why we believe electrochemistry education will shape the future of this industry.

Memristive switching of nanofluidic diodes by ionic concentration gradients

We demonstrate that nanofluidic diodes exhibit a memristive behavior that can be controlled not only by the amplitude and frequency of the driving oscillatory signal but also by changing the relative orientations of the externally imposed ionic concentration difference with respect to the pore charge density gradient. Because ionic concentration differences, memristive properties, and nanofluidic pores are of broad interest to electrochemical technology and membrane bioelectrochemistry, this study can be a useful contribution to the field. In our case, the memristor is a polymer membrane with current rectifying conical nanopores. The electrical interaction between the mobile ions in the aqueous solution and the pore surface charges leads to rich physico-chemical phenomena, including memory effects and the neuromorphic-like potentiation of the membrane conductance following voltage pulses (spikes). The multipore membrane can be used in the design of electrochemical circuits for signal conversion and information processing in iontronic hybrid devices.

Palladium nanocubes-mediated Fenton catalysis combined with chloride ion-amplified electro-driven catalysis for dye degradation

Electrochemical technology is frequently used to treat industrial dye wastewater. However, its degradation efficiency is restricted by pH, and the low current efficiency and high energy consumption limit its broader application. Based on this, we constructed an innovative electro-driven catalytic system by integrating nanotechnology with electric current. This system operates without pH constraints, has low energy consumption, and allows for the recycle and reuse of both electrodes and catalysts. Firstly, we synthesized palladium (Pd) cubes via a solvothermal method, and characterized their morphology, structural composition, and crystalline properties using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other methods. The prepared Pd cubes possessed dual catalytic properties of electro-driven catalysis and Fenton catalysis, achieving a synergistic degradation effect under an electric field. Subsequently, the study explored how catalysts dosage, H2O2 concentration, pH and Cl− concentration affect the catalytic rate. The optimized system was able to degrade 99.17 % of MB within 1 h and was effective against various organic pollutants. After five cycles of reuse, the recovered catalysts maintained over 90 % degradation efficiency in decomposing MB. This process realizes efficient degradation with a low concentration of catalysts, offering a novel approach for nanotechnology in wastewater treatment under electro-driven conditions.

Design of Multifunctional Electrocatalysts for ORR/OER/HER/HOR: Janus Makes Difference.

Multifunctional electrocatalysts for hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) have broad application prospects; However, realization of such kinds of materials remain difficulties because it requires the materials to have not only unique electronic properties, but multiple active centers to deal with different reactions. Here, employing density functional theory (DFT) computations, it is demonstrated that by decorating the Janus-type 2D transition metal dichalcogenide (TMD) of TaSSe with the single atoms, the materials can achieve multifunctionality to catalyze the ORR/OER/HER/HOR. Out of sixteen catalytic systems, Pt-VS (i.e., Pt atom embedded in the sulfur vacancy), Pd-VSe, and Pt-VSe@TaSSe are promising multifunctional catalysts with superior stability. Among them, the Pt-VS@TaSSe catalyst exhibits the highest activity with theoretical overpotentials ηORR = 0.40V, ηOER = 0.39V, and ηHER/HOR = 0.07V, respectively, better than the traditional Pt (111), IrO2 (110). The interplays between the catalyst and the reaction intermediate over the course of the reaction are then systematically investigated. Generally, this study presents a viable approach for the design and development of advanced multifunctional electrocatalysts. It enriches the application of Janus, a new 2D material, in electrochemical energy storage and conversion technology.

Electrochemical advanced oxidation of glucosinolates derived from rapeseed meal: Parameter optimization, degradation mechanism and toxicity assessment

Glucosinolates (GLS) are a group of antinutritional compounds present in rapeseed meal that limit its use as feed ingredients. Considering their potentially hazardous effects on both the aquatic environment and animal health, it is necessary to develop green and efficient degradation options for GLS. In the current work, the electrochemical advanced oxidation technology with a boron-doped diamond (BDD) electrode was initially employed for the degradation of GLS. To facilitate parameter optimization, a sequential strategy comprising a definitive screening design and a central composite rotatable design was implemented. Particular attention was paid to the differing roles of five electrolyte salts (NaCl, NaNO3, Na2SO4, NaHCO3 and Na3PO4) during the electrolytic oxidations. The optimal conditions for GLS degradation were found to be a flow rate of 400 mL min−1, a applied current density of 7.75 mA cm−2 and a 2.0 mM NaNO3 medium, yielding mineralization of 82.2 % at 120 min of electrolysis. By combining the results of computational simulation and LC/MS analysis, four possible degradation pathways of allyl GLS at the BDD anode were proposed. And the ecotoxicity of each detected degradation product was determined using the ECOSAR program. Further biological toxicity assay revealed that crude GLS electrolysis reduced the toxicity on model organism Caenorhabditis elegans, reducing its death percentage by 26.80 % and its lipofuscin level by 37.59 % at 48 h. The results showed great promise of BDD technology in engineering applications as a powerful option for the treatment of GLS derived from rapeseed meal.

Electrochemical Technology for New Materials Synthesis and Reprocessing

It is difficult to underestimate the role of electrochemistry in the modern world [...]

Humic acid as eco‐friendly corrosion inhibitor for EH40 ship plate steel

In this study, a new type of green corrosion inhibitor, namely, sodium humate (SH), was extracted from humus soil, which is a natural humus plant, by dissolution‐neutralization, and then used for corrosion inhibition of low carbon steel in seawater. The corrosion inhibition performance of SH on low carbon steel EH40 in seawater was tested by weight loss method and electrochemical technology. The surface and corrosion products of low carbon steel were observed and analyzed by scanning electron microscope (SEM), atomic force microscope (AFM), contact angle and X‐ray photoelectron spectroscopy (XPS). The results show that SH is a mixed corrosion inhibitor, and the optimum concentration is 2 g L−1. At this concentration, the inhibition rate can reach 93.6%. It mainly affects the semi‐reaction of cathodic corrosion. By forming a corrosion protection layer with uniform adsorption on the surface of EH40 steel, EH40 steel becomes more resistant to seawater corrosion.

Exploring the mechanism of removing Cd from polluted soil using electrochemical leaching with straw carbon film electrode

The study presents a novel approach to remediating heavy metal-contaminated soil using electrochemical technology and chemical leaching. The researchers developed a new electrode material from waste straw and an environmentally friendly leaching agent using straw fermentation liquid. Combining electrochemical technology with chemical leaching provides a powerful remediation solution for heavy metal-contaminated soil, demonstrating efficiency and thoroughness. However, challenges include developing recyclable electrode materials and environmentally friendly leaching agents. This study addresses these challenges by pioneering a biochar-based electrode material and an eco-friendly leaching agent. Waste straw undergoes pyrolysis at 1000 °C to produce a conductive biochar, which is then combined with ethyl cellulose to form a film, creating biochar electrode materials. The developed straw fermentation solution, an environmentally friendly leaching agent, is used for Cd-contaminated soil remediation through combined electrochemical-chemical leaching. Results show soil Cd removal efficiency peaking at 59.5% with a singular chemical leaching agent. The combined method increases the Cd removal rate to a maximum of 91%. Furthermore, the study elucidate the potential mechanism of cadmium removal through techniques such as XRD, SEM, and infrared spectroscopy. To evaluate the efficacy of our approach, the study conducted Chinese cabbage pot-cultivation experiments. Remarkably, the physicochemical properties of soil remained largely unchanged after the reaction, while Chinese cabbage growth in treated soil surpassed that of the control group. This study not only removes Cd from the soil, reducing secondary pollution, but also establishes electrode recyclability, offering a prospective solution for large-scale soil heavy metal pollution remediation.

Electrochemical Sensor for the Detection and Accurate Early Diagnosis of Ovarian Cancer.

Ovarian cancer (OC) has the highest mortality rate among malignant tumors, primarily because it is difficult to diagnose early. Exosomes, a type of extracellular vesicle rich in parental information, have garnered significant attention in the field of cancer diagnosis and treatment. They play an important regulatory role in the occurrence, development, and metastasis of OC. Consequently, exosomes have emerged as noninvasive biomarkers for early cancer detection. Therefore, identifying cancer-derived exosomes may offer a novel biomarker for the early detection of OC. In this study, we developed a metal-organic frameworks assembled "double hook"-type aptamer electrochemical sensor, which enables accurate early diagnosis of OC. Under optimal experimental conditions, electrochemical impedance spectroscopy technology demonstrated a good linear relationship within the concentration range of 31-3.1 × 106 particles per microliter, with a detection limit as low as 12 particles per microliter. The universal exosome detection platform is constructed, and this platform can not only differentiate between high-grade serous ovarian cancer (HGSOC) patients and healthy individuals but also distinguish between HGSOC patients and nonhigh-grade serous OC (non-HGSOC). Consequently, it provides a novel strategy for the early diagnosis of OC and holds great significance in clinical differential diagnosis.

Tailoring the Size of Reduced Graphene Oxide Sheets to Fabricate Silicon Composite Anodes for Lithium-Ion Batteries.

The integration of a silicon (Si) anode into lithium-ion batteries (LIBs) holds great promise for energy storage, but challenges arise from unstable electrochemical reactions and volume changes during cycling. This study investigates the influence of reduced graphene oxide (rGO) size on the performance of rGO-protected Si composite (Si@rGO) anodes. Two sizes of graphene oxide (GO(L) and GO(S)) are used to synthesize Si@rGO composites with a core-shell structure by spray drying and thermal reduction. Electrochemical evaluations show the advantages of the Si@rGO(S) anode with improved cycle life and cycling efficiency over Si@rGO(L) and pure Si. The Si@rGO(S) anode facilitates the formation of a stable LiF-rich solid electrolyte interface (SEI) after cycling, ensuring enhanced capacity retention and swelling control. Rate capability tests also demonstrate the superior high-power performance of Si@rGO(S) with low and stable resistances in Si@rGO(S) over extended cycles. This study provides critical insights into the tailoring of graphene-protected Si composites, highlighting the critical role of rGO size in shaping structural and electrochemical properties. The Si material wrapped by graphene with an optimal lateral size of graphene emerges as a promising candidate for high-performance LIB anodes, thereby advancing electrochemical energy storage technologies.

Removal of reactive black 5 in water using adsorption and electrochemical oxidation technology: kinetics, isotherms and mechanisms

AbstractIn this work, a novel graphite intercalation compound (GIC) particle electrode was used to investigate the adsorption of Reactive Black 5 (RB5) and the electrochemical regeneration in a three-dimensional (3D) electrochemical reactor to recover its adsorptive capacity. Various adsorption kinetics and isotherm models were used to characterise the adsorption behaviour of GIC. Several adsorption kinetics were modelled using linearised and non-linearised rate laws to evaluate the viability of the sorption process. Studies on the selective removal of RB5 dyes from binary mixture in solution were evaluated. RSM optimisation studies were integrated with ANOVA analysis to provide insight into the significance of selectivity reversal from the salting effect of textile dye solution on GIC adsorbent. A unique range of adsorption kinetics and isotherms were used to evaluate the adsorption process. Non-linear models best simulated the kinetic data in the order: Elovich > Bangham > Pseudo-second-order > Pseudo-first-order. The Redlich–Peterson isotherm was calculated to have a dye loading capacity of 0.7316 mg/g by non-linear regression analysis. An error function analysis with ERRSQ/SSE of 0.1390 confirmed the accuracy of dye loading capacity predicted by Redlich–Peterson isotherm using non-linear regression analysis. The results showed that Redlich–Peterson and SIPS isotherm models yielded better fitness to experimental data than the Langmuir type. The best dye removal efficiency achieved was ~ 93% using a current density of 45.14 mA/cm2, whereas the highest TOC removal efficiency achieved was 67%.

Electrochemically Enhanced Forward Osmosis Processes Unlocking Efficiency and Versatility

AbstractThe growing interest in forward osmosis (FO) for water reclamation and desalination over the past two decades stems from its potential for lower energy consumption. Despite its promise, FO faces significant challenges, such as the lack of an appropriate draw solute, concentration polarization, membrane fouling, and reverse solute flux (RSF). Recent trends in research have focused on combining various technologies with FO to address these challenges. Notably, the integration of electrochemical technologies with FO offers new possibilities. This review covers FO combined with electrochemical cells (FO‐ECs), categorizing them based on their working principles and applications in improving FO. The review discusses different FO‐EC configurations, including (1) electrodialysis‐combined FO for RSF, (2) electro‐FO for water flux enhancement, and (3) electrochemical oxidation‐combined FO and FO with electro‐conductive membranes for self‐cleaning and fouling mitigation. Additionally, it covers (4) reusable electro‐responsive draw solutes, (5) electrochemical osmosis systems for metal removal and energy production, and (6) osmotic microbial fuel cells for energy recovery and other benefits. The review also assesses the practical applicability and potential for achieving carbon neutrality of the FO‐ECs. It concludes with a forward‐looking perspective, outlining future research directions to optimize and expand the use of electrochemical‐enhanced FO technologies.

Corrosion and Protection of Electrocatalysts toward Advanced Energy Technologies

AbstractHigh‐efficiency electrocatalysts play an important role in clean energy conversion technologies. Generally, electrocatalysts in different environments, including voltage, acid, and alkali electrolytes, are more susceptible to corrosion, which will induce structural and performance changes. Based on the latest achievements in the corrosion and protection of electrocatalysts in advanced energy technologies, this review mainly studies the application of various corrosion strategies to construct superior electrocatalysts, including chemical etching, metal corrosion transformation, and corrosion reconstruction, and their affecting factors are also appraised and summarized. To improve the stability of electrocatalysts, various corrosion inhibition strategies, such as carrier improvement and composition regulation accompanied by structure optimization, are reviewed. In addition, the application of catalyst corrosion in electrochemical energy technologies is examined from the perspective of the structure‐activity‐performance relationship. In the end, this article concludes the perspective and challenges of electrocatalyst corrosion in energy conversion and storage technologies. This article provides insights and directions for designing electrocatalysts with high efficiency and low corrosion, which is beneficial for developing corrosion chemistry for sustainable energy technologies.

Insight into the crevice corrosion mechanism of AA7075‐T651 high‐strength aluminum alloys in neutral nitrate solution: The effect of Cl−

AbstractThe crevice corrosion behavior and mechanism of AA7075‐T651 aluminum alloy was investigated by electrochemical measurements and surface analysis technologies in a neutral nitrate solution with different contents of NaCl. The Cl− was identified as crucial for the initiation and development of the crevice corrosion, with the phenomenon absent in the 0.05 M NaCl solution but initiated in the 0.5 and 1 M NaCl solutions. However, the crevice corrosion was more pronounced in the 0.5 M NaCl solution due to the establishment of a larger galvanic corrosion effect. The rapid dissolution of the anodic phase resulted in the increased Cl− inside the crevice, while the cathodic phase enhanced the localized dissolution through micro‐galvanic corrosion. This synergistic effect significantly facilitated the development of crevice corrosion.

Ball type (4-(tert-butyl)-1,2-phenylene)dimethanolate bridged dinuclear metallo phthalocyanines: Synthesis, characterization, electrochemistry, and in situ spectroelectrochemistry

In this research, cofacial ball type metallo phthalocyanines (MPcs) with a longer bridge, which by adding a –CH2 group to the oxo bridge, were obtained by working the 4,4′-(((4-(tert-butyl)-1,2-phenylene)bis(methylene))bis(oxy))diphthalonitrile beginning complex. Molecular characterizations of the starting compound and dinuclear ball-type MPcs (Co, Fe, Mn, Zn, Ni) obtained from it were made using elemental analysis, 1H-NMR, 13C-NMR, FT-IR, UV–Vis, and MALDI-TOF mass spectroscopy. In addition, how the macromolecule’s spectral, electrochemical, in situ spectroelectrochemical, and electrochromic properties changed was investigated when the phthalocyanine (Pc) rings moved away from each other due to the increasing linking bridge length. The electrochemical properties of ball-type Pcs were investigated via Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV) in the non-aqueous solvent system on a Pt working electrode (WE). In situ spectroelectrochemical measurements also were carried out to support the electrochemical measurements. In situ electrocolorimetric techniques revealed color changes relevant to the redox processes. Electrochemical and spectroelectrochemical measurements showed that ball type metallo-Pcs form steadfast mixed-valence species based on metal and/or Pc ring on account of the fact that there are forceful and striking intramolecular interactions between the two Pc segments. As a result of the cofacial molecular structure of ball type metallo-Pcs and the split molecular orbitals, the complexes have rich redox properties. They can be utilized as a material in electrochemical technologies since they have plentiful redox behaviors. In situ spectroelectrochemical and in situ electrocolorimetric measurements demonstrated that they also have rich spectral and chromatic features. Due to the apparent color and spectral variations, they are appropriate for electrochromic appliances.

Cellulose nanofiber enabled high-mass loading N-doped porous carbon electrode for zinc-ion supercapacitors

Zinc-ion hybrid supercapacitors (ZHSCs) are among the most promising electrochemical energy storage technologies because of their high energy density, environmental sustainability, low price, and inherent security. High-load, high-capacity cathodes are critical for the practical application of ZHSCs. However, it is challenging to achieve optimal performance of high-loading electrodes due to slow reaction kinetics, retarded ion transport, and structural instability. Herein, a salt-template technique was used to fabricate nitrogen-doped porous carbon (NPC) with large surface area, abundant mesopores, and electroactive nitrogen dopants. When combined with a fibrous network scaffold of carbon nanotubes and cellulose nanofibers (CNT/CNF), the optimized NPC delivered an outstanding specific capacitance of 133.4 mAh g−1 and a remarkable capacity retention of 95.4% after 10,000 cycles. More impressively, we achieved a cathode with high mass-loading of 10 mg cm−2 without significantly sacrificing the electrochemical performance (area capacity of 2.05 mAh cm−2 and good cycling stability with capacity retention of 86.2% after 3000 cycles). The excellent performance can be attributed to the continuous electron/ion conduction pathways of CNT/CNF scaffold and redox-active surface generated by the favorable heteroatom-doped porous carbon. In sum, this work offers a platform for making high mass-loading carbon electrodes for practical ZHSCs.

Atomic Molybdenum Nanomaterials for Electrocatalysis.

As a sustainable energy technology, electrocatalytic energy conversion requires electrocatalysts, which greatly motivates the exploitation of high-performance electrocatalysts based on nonprecious metals. Molybdenum-based nanomaterials have demonstrated promise as electrocatalysts because of their unique physiochemical and electronic properties. Among them, atomic Mo catalysts, also called Mo-based single-atom catalysts (Mo-SACs), have the most accessible active sites and tunable microenvironments and are thrivingly explored in various electrochemical conversion reactions. A timely review of such rapidly developing topics is necessary to provide guidance for further exploration of optimized Mo-SACs toward electrochemical energy technologies. In this review, recent advances in the synthetic strategies for Mo-SACs are highlighted, focusing on the microenvironment engineering of Mo atoms. Then, the representative achievements of their applications in various electrocatalytic reactions involving the N2, H2O, and CO2 cycles are summarized by combining experimental and computational results. Finally, prospects for the future development of Mo-SACs in electrocatalysis are provided and the key challenges that require further investigation and optimization are highlighted.

Influence of Different Proportions of the Addition of Electrocoagulated Metal Sludge (EMS) Obtained from Oily Wastewater Treatment on the Properties of Laboratory Bricks

Electrochemical wastewater treatment technologies are increasingly being used in practice, and the combination of electrocoagulation with advanced oxidation processes has been shown to increase treatment efficiency. The treatment of oily wastewater produces electrocoagulated metal sludge (EMS). In this work, the possibility of using different ratios of EMS produced during oily wastewater treatment was investigated. EMS was dried conventionally in an oven at 105 °C and used as a partial substitute for clay in the manufacture of laboratory bricks. The main research objectives of this study were to examine the possibility and justification of introducing EMS in brick production. The results show that an increase in the proportion of EMS in the manufacturing of bricks leads to a deterioration in the quality of the bricks. Bricks with an addition of 1 wt% and 5 wt% EMS showed the best properties. The loss on ignition (LOI), compressive strength, boiling water absorption and initial water absorption were determined at 5.7%; 49 N/mm2, 16%, 14 g/min/200 cm2, 15% for modified bricks with 1 wt% EMS and 6.3%, 48 N/mm2, 20%, 15 g/min/200 cm2 for modified brick with 5 wt%.

Effect of graphene oxide on CoCrFeNi high-entropy alloy coatings prepared by the electrodeposition method

The performance advantages of high-entropy alloy (HEA) have become a consensus. However, the current preparation methods are mostly focused on thermal processing methods, and the research on the preparation of HEA coatings using electrochemical technology is generally rare. Therefore, in this study, the CoCrFeNi HEA coating was synthesized by electrodeposition technology and the effect of graphene oxide (GO) concentration on the microstructure and tribological property of the HEA coating was further studied. The results showed that during the electrodeposition process, the four atoms of Co, Cr, Fe and Ni were co-deposited to form the HEA coating with a face-centered cubic crystal structure. The introduction of GO did not change the crystal structure of HEA coatings, and GO was also co-deposited with metal atoms to form the HEA-GO composite coating. Meanwhile, GO was distributed in composite coatings in the form of being encapsulated by the metal layer. The addition of GO improved the compactness of HEA coating and reduced the surface roughness. The increase in GO concentration helped to inhibit the formation of the stress-induced cracks on the surface of the composite coating, and significantly enhanced the wear resistance of HEA coating. When the GO concentration was 0.2 g/L, the wear resistance was the best. The wear form of composite coatings was independent of GO and its concentration, and was dominated by abrasive wear.

Electrochemical ocean iron fertilization and alkalinity enhancement approach toward CO2 sequestration

Achieving net-zero emissions by 2050 requires the development of effective negative emission techniques, including ocean-based approaches for CO2 sequestration. However, the implementation and testing of marine CO2 removal (mCDR) techniques such as ocean iron fertilization (OIF) or ocean alkalinity enhancement (OAE) face significant challenges. Herein, a novel self-operating electrochemical technology is presented that not only combines OIF and OAE, but also recovers hydrogen gas (H2) from seawater, hence offering a promising solution for achieving quantifiable and transparent large-scale mCDR. Experimental results show that the electrochemical OIF (EOIF) can not only increase the concentration of ferrous iron (Fe+2) by 0–0.5 mg/L, but also significantly increases the seawater pH by 8% (i.e., a 25% decrease in the hydrogen ions concentration). The release of iron (Fe+2/Fe+3) can be regulated by adjusting the magnitude of the electric current and its form (e.g., pulsed current and polarity reversal), as well as by optimizing the electrode material and geometry. In certain ocean regions, enhanced iron concentrations stimulate the naturally occurring biological carbon pump (BCP), leading to increased phytoplankton growth, CO2 uptake, and subsequent export of carbon to the deep ocean. Simultaneously, the system increases seawater alkalinity and the buffer capacity, enhancing CO2 solubility and storage in the shallow ocean through the solubility pump. The obtained measurements demonstrate the scalability of EOIF and its ability to operate using solar energy at a lower cost. Overall, the proposed EOIF technology offers a practical, effective, and sustainable solution for addressing climate change on a large scale.