Cathode Electrode Research Articles

Closed-Loop Graphite Recycling from Spent Lithium-Ion Batteries through Bioleaching

Research into the recycling of electrode materials has gained attention due to the exponential increase in spent and discarded lithium-ion batteries (LIBs). While cathode electrode recovery has perennially been a research priority due to its economic benefits, anode electrode (graphite) recycling has yet to be accomplished. Currently, the focus has shifted to recycling the anodes from spent LIBs to deal with the scarcity of graphite resources and protect the environment because the anode is a crucial part of a LIB. The primary goal of this research is to recycle and regenerate anode graphite from the bioleaching residue. Unlike other hydrometallurgical LIB recycling, the bioleaching residue contains a considerable amount of iron salts with unleached cathode metal. Graphite was recycled using mild acid cleaning to remove vast amounts of iron salts and unleached cathode materials, followed by calcination treatments. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis revealed that the regenerated graphite had a purity of 99.78%. The morphology and structure of the regenerated graphite were confirmed to be identical to the commercial material using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The regenerated graphite samples show excellent electrochemical performance, with a charging/discharging capacity higher than 400 mAh/g and a retention rate of 100% after 200 cycles, surpassing commercial graphite (366 mAh/g).

A high-rate cathode material based on potassium-doped Na3V2(PO4)3 for high/low-temperature sodium-ion batteries

Na3V2(PO4)3, with its three-dimensional NASICON structure and an excellent reversible capacity, is one of the most promising cathode materials for sodium-ion batteries. To overcome the poor rate performance of the Na3V2(PO4)3 electrode caused by the structural damage during Na ion insertion/extraction at low-temperature, an appropriate amount of K ions has been doped into Na3V2(PO4)3 by a rational design to enlarge the unit cell volume, which broadens the Na ion migration channel and ensures a significant improvement in the rate performance of the Na3V2(PO4)3 electrode under all-climate (−25 °C–40 °C). The results indicate that the as-prepared Na3-xKxV2(PO4)3 not only provides rapid molecular dynamics of sodium ions but also improves the structural stability. A remarkable electrochemical performance of the Na2.95K0.05V2(PO4)3 cathode electrode can be obtained even at high current densities (a reversible capacity 80.2 mAh/g at 100 C with a temperature of 40 °C). Moreover, Na2.95K0.05V2(PO4)3 can still maintain a capacity of 72 mAh/g at 2 C under a low temperature of −25 °C, while the undoped Na3V2(PO4)3 has almost no capacity. This article provides a promising strategy to cope with the long-standing inherent all-climate issues of sodium ion batteries and broaden the application of rechargeable batteries.

Construction of novel cyanobacteria-based biological photovoltaic solar cells: Hydrogen and photocurrent generated via both photosynthesis and respiratory system

Biological photovoltaic (BPV) cells use biological organisms in order to produce clean electrical power by capturing solar energy. In this study, a cyanobacteria based BPV cell was constructed and it generated H2 gas and photocurrent via photosynthesis and respiratory system. This kind of BPV cell was constructed in which the cathode and photoanode are gold electrodes coated with different conjugated polymers and these polymers are combined to Pt or Au nanoparticles with oligoaniline bonds. Unlike the cathode electrode, a kind of cyanobacteria (Leptolyngbia sp.) was used in the design of photoanode and bounded to Au NPs with oligoaniline bonds. For the configuration of cathode in BPV cell, a gold electrode was first coated with a dithienylpyrrole-based conductive polymer with an amine open-ended aniline functional group. This conductive polymer was then attached to mercapto-aniline functionalized Pt nanoparticles with oligoaniline bonds. In the case of photoanode in BPV cell, this time, a dithienopyrrole-based conductive polymer with an aniline subunit was coated on another Au electrode surface via electrochemical polymerization. This polymer provides to connect oligoaniline modified Au nanoparticles with coating cyanobacteria. Some control and optimization experiments for photoanode of the system were done in order to understand photosynthesis formation and get efficient photocurrent from BPV cell. The system was illuminated under visible light and a constant potential and then the decomposition of water in BPV solar cell system was observed via photosynthesis by cyanobacteria with the formation of H2 and O2 gases besides photocurrent generation. Another photocurrent generation via respiratory system of cyanaobacteria was also investigated in the medium of glucose after diuron (PS II inhibitor an inhibitor) was added into medium. By using two different properties (photosynthesis and respiratory system) of cyanobacteria, BPV solar system generates high amount of photocurrent and hydrogen.

Identifying the engagement of a brain network during a targeted tDCS-fMRI experiment using a machine learning approach.

Transcranial direct current stimulation (tDCS) can noninvasively modulate behavior, cognition, and physiologic brain functions depending on polarity and dose of stimulation as well as montage of electrodes. Concurrent tDCS-fMRI presents a novel way to explore the parameter space of non-invasive brain stimulation and to inform the experimenter as well as the participant if a targeted brain region or a network of spatially separate brain regions has been engaged and modulated. We compared a multi-electrode (ME) with a single electrode (SE) montage and both active conditions with a no-stimulation (NS) control condition to assess the engagement of a brain network and the ability of different electrode montages to modulate network activity. The multi-electrode montage targeted nodal regions of the right Arcuate Fasciculus Network (AFN) with anodal electrodes placed over the skull position of the posterior superior temporal/middle temporal gyrus (STG/MTG), supramarginal gyrus (SMG), posterior inferior frontal gyrus (IFG) and a return cathodal electrode over the left supraorbital region. In comparison, the single electrode montage used only one anodal electrode over a nodal brain region of the AFN, but varied the location between STG/MTG, SMG, and posterior IFG for different participants. Whole-brain rs-fMRI was obtained approximately every three seconds. The tDCS-stimulator was turned on at 3 minutes after the scanning started. A 4D rs-fMRI data set was converted to dynamic functional connectivity (DFC) matrices using a set of ROI pairs belonging to the AFN as well as other unrelated brain networks. In this study, we evaluated the performance of five algorithms to classify the DFC matrices from the three conditions (ME, SE, NS) into three different categories. The highest accuracy of 0.92 was obtained for the classification of the ME condition using the K Nearest Neighbor (KNN) algorithm. In other words, applying the classification algorithm allowed us to identify the engagement of the AFN and the ME condition was the best montage to achieve such an engagement. The top 5 ROI pairs that made a major contribution to the classification of participant's rs-fMRI data were identified using model performance parameters; ROI pairs were mainly located within the right AFN. This proof-of-concept study using a classification algorithm approach can be expanded to create a near real-time feedback system at a participant level to detect the engagement and modulation of a brain network that spans multiple brain lobes.

A complementary electrochromic device based on Prussian Blue and Tungsten Trioxide: The influence of switching time operation on high performance and long-term stability

The sustainability of electrochromic devices has been heavily focused on both novel materials and electrolytes. Nonetheless, profound research into the operation of electrochromic devices have typically gone unnoticed. Accordingly, there is still a scarcity of research related to a systematic approach to driving principles of electrochromic devices such as the balanced electrochemical process between the anodic and the cathodic electrodes. Based on fundamental electrochemistry, there are three possible causes of poor performance and cycle stability in an electrochromic device: (1) charge is not equally shuttled between Prussian blue (PB) and tungsten trioxide (WO3), (2) irreversible ions are trapped within PB and/or WO3, and (3) PB and/or WO3 deterioration. Herein, this study discovered the impact of switching time operation on a complementary electrochromic device based on PB and WO3, providing a potentially novel direction for enhancing and controlling the electrochromic performance in smart windows or display applications.

Gas-fed liquid-covered electrodes used for electrochemical reduction of dilute CO2 in a flue gas

Direct electrochemical reduction of dilute CO2 in a flue gas eliminates the energy-consuming preprocesses of capture and condensation for preparing 100% CO2 gas, and hence could decrease the total energy consumption for utilization of emitted CO2. However, it raises two major issues: (i) insufficient supply rate of CO2 to the cathode electrode and (ii) preferential reduction of O2; both lower the Faradaic efficiency of the target reaction of CO2 reduction. To solve these issues, we propose a new concept of gas-fed liquid-covered electrodes (GFLCEs). The reaction gas is fed to the catalyst layer across a thin liquid cover layer formed by a combination of hydrophilic and hydrophobic porous films. Owing to an extremely lower solubility of O2 in an aqueous electrolyte than that of CO2, the O2 concentration in the catalyst layer is sufficiently decreased while securing high CO2 concentration. In the GFLCE, the catalyst is entirely immersed in the electrolyte contrasting to those of conventional gas-diffusion electrodes. Therefore, a CO2 capture medium including monoethanolamine (MEA) added in the electrolyte increases the effective CO2 concentration. We applied the GFLCE concept with MEA to a Ru-complex-based electrocatalyst for formate production, and achieved high Faradaic efficiencies of around 70% under direct feeding of a simulated flue gas of 15% CO2 + 4% O2 + 81% N2 (v/v). The present concept proved here with the MEA additive is a versatile means applicable to existing electrocatalysts.

The Electrochemical removal of Oil and COD from petroleum wastewater

Recently, COD and oil concentrations in the water have increased, as a result of reduced water volumes and increased industrial waste being dumped into the river. Increased concentrations of these pollutants lead to health and environmental problems. As the water treatment plants use the usual methods of water treatment and could not reduce the concentration of oil and COD to the limit set by the World Health Organization, so an effective way to treat these pollutants became absolutely necessary. In this study, electrochemical method was used to treat water contaminated with oil and COD, using aluminium and iron electrodes as positive electrode and cathode electrode. A coagulation cell with a volume of 2 litters was also used in the work. Several factors affecting the process of treating oil and carbon dioxide pollutants were studied, and these factors were as follows: Submerge depth, Number of electrodes, the distance between the electrodes. From the results, it was found that the optimum removal was 94.2% for oil, and 99.5% for COD. It was achieved when the number of electrodes was 4 aluminium and 4 irons, the distance between the electrodes was 2 cm, the depth was 12 cm, and the function variables were acidic equal to 7, time 50 min, and voltage 10.5 V. The concentration of sodium chloride is 0.5 g/l and the electrode material is aluminium as anode and cathode and the initial oil concentration is 95 mg per litter, initial COD concentration is 710 mg per litter and the consumption of energy was estimated to be 12 kwh/m³, the TSS was 73 mg/l. The results demonstrated that the electrochemical is a feasible technique for treatment of oily contaminated petroleum refinery wastewater.

Simulating the Impact of Glassy Carbon Foam Electrodes on the Performance of Sodium Iodine Batteries

This publication examines the influences of glassy carbon foam electrodes on the overall battery performance of secondary sodium iodine batteries. The battery combines a molten sodium anode and an iodine-based cathode with NaSICON serving as a ceramic separator. The battery system works at 100 °C and is suitable for stationary energy storage. A long cycle life and good resource utilization are major concerns for establishing the proposed battery system. This paper employs a spatially resolved simulation approach to investigate the effects of foam electrodes of different porosities and cell sizes on the charging and discharging behavior. The spatially resolved model reflects species and mass transport as well as electrochemical processes and reactions in the positive half cell. An open-pored glassy carbon foam cathode structure shows an improved utilizable capacity compared to a simpler two-dimensional electrode. Parameter studies of foam porosity and specific surface area indicate that porosity is the crucial parameter for achievable depth of discharge. We conclude that glassy carbon open-pored foam of preferably high porosity is a suitable material for cathode electrodes in sodium iodine batteries.

Study of the Electrophysical Properties of Solid Solutions with a Perovskite Structure in La2O3–SrO–Ni(Co,Fe)2O3–δ Systems for Cathode Electrodes for Fuel Cells

Study of the Electrophysical Properties of Solid Solutions with a Perovskite Structure in La2O3–SrO–Ni(Co,Fe)2O3–δ Systems for Cathode Electrodes for Fuel Cells

Magnetic field induced synthesis of (Ni, Zn)Fe2O4 spinel nanorod for enhanced alkaline hydrogen evolution reaction

Recently, the introduction of external fields (light, thermal, magnetism, etc.) during electrocatalysis reactions gradually becomes a new strategy to modulate the catalytic activities. In this work, an external magnetic field was innovatively employed for the synthesis progress of (Ni, Zn)Fe2O4 spinel oxide (M-(Ni, Zn)Fe2O4). Results indicated the magnetic field (≤250 ​mT) would affect the morphology of catalyst due to the existing Fe ions, inducing the M-(Ni, Zn)Fe2O4 nanosphere particles to be uniform and coral-like nanorods. In addition, the electronic structure of the catalyst was regulated by the valence state of Fe, changing the bonding of metal to oxygen atoms in different spinel sites. The results manifested that the M-(Ni, Zn)Fe2O4 requires a lower overpotential of only 67 ​mV to deliver 10 ​mA ​cm−2 for hydrogen evolution reaction (HER) in alkaline electrolyte. Moreover, M-(Ni, Zn)Fe2O4 respectively as the anode and cathode electrode for the overall water splitting, the catalysis system requires a cell voltage of only 1.76 ​V to gain a current density of 50 ​mA ​cm−2, combining with an excellent discharging stability after 10 ​h. This work provides a facile synthesis strategy toward the design of efficient non-noble metal catalysts for alkaline HER and overall water splitting.

Stabilized electrode phase by prelithiating V2O5 cathode materials for high-specific energy thermal batteries

Vanadium pentoxide (V2O5) is an attractive high-energy cathode material for thermal batteries but is limited by the high solubility and tendency to react with halogenic molten salt. LixV2O5 (0 < x ≤ 1) are expected to take the place of V2O5 as the promising cathode materials in thermal batteries. In this work, LixV2O5 were successfully synthesized by the high-efficiency and low-cost method, which uses the molten salt as lithium source and through a brief-time sintered process (900 °C for 15 s). LixV2O5/molten salt electrode with CNTs conductive agent exhibits an original discharge voltage with 2.51 V and a specific capacity up to 309.46 mA h g−1. The high chemical stabilization between LixV2O5 and molten salt which could increase interfacial structure stabilization and improve the transmission rate of Li+. Besides, CNTs could build the continuous electron transport channels in active cathode inter-particles and improve the utilization rate of LixV2O5. This paper not only prepares the LixV2O5 cathode materials with high specific capacity via a simple method, but also provides insights into the phase evolution process of V2O5 based cathode electrodes during discharge process of thermal batteries.

N-doped GO cathode catalyst boosting capacity of denitrification for air-cathode microbial fuel cell by shifting microbial community composition in treating marine wastewater

Air-cathode microbial fuel cell (AMFC) is a promising technology with considerable potential for treating contaminants, while obtaining energy has gained a substantial interest. The oxygen reduction reaction (ORR) performance of the cathode electrode is the pivotal factor for boosting AMFC ability. In this study, nitrogen-doped GO cathodic catalysts were prepared using direct heat treatment (NGO) and one-step hydrothermal method (H-NGO). The electrochemical experiments showed the AMFC equipped with NGO10 (wt% of urea: GO was 10:1) achieved the highest output voltage of 391.8 mV with a power density of 1800 mWm-3 in comparison with H-NGO and Pt/C electrodes, i.e. The diversity of bacterial communities for different biofilms was analyzed using high-throughput sequencing, the result showed the relative abundance of denitrifying bacteria including Marinobacter (34.9 %), Methylophaga (4.6 %), Pseudidiomarina (2.7 %) and Glaciecola (3.0 %) significantly increased at cathodic biofilms, moreover, Marinobacter, Methylophaga and Arcobacter were enriched at NGO10 cathode electrode. Reconstruction of Unobserved States (PICRUSt2) predicted differences in metabolic pathways between anode and cathode biofilm, indicating that L-threonine metabolism was significantly down-regulated, while spirilloxanthin, 2,2′-diketo-spirilloxanthin biosynthesis and syringate degradation were significantly up-regulated. A real-time PCR (RT-PCR) represented the genes related to denitrification involving napA, nirK, nirS, nosZ and norB possessed relative higher expression in NGO10 cathode biofilm.

Nitrogen-Doped Graphene Oxide as Efficient Metal-Free Electrocatalyst in PEM Fuel Cells

Nitrogen-doped graphene is currently recognized as one of the most promising catalysts for the oxygen reduction reaction (ORR). It has been demonstrated to act as a metal-free electrode with good electrocatalytic activity and long-term operation stability, excellent for the ORR in proton exchange membrane fuel cells (PEMFCs). As a consequence, intensive research has been dedicated to the investigation of this catalyst through varying the methodologies for the synthesis, characterization, and technologies improvement. A simple, scalable, single-step synthesis method for nitrogen-doped graphene oxide preparation was adopted in this paper. The physical and chemical properties of various materials obtained from different precursors have been evaluated and compared, leading to the conclusion that ammonia allows for a higher resulting nitrogen concentration, due to its high vapor pressure, which facilitates the functionalization reaction of graphene oxide. Electrochemical measurements indicated that the presence of nitrogen-doped oxide can effectively enhance the electrocatalytic activity and stability for ORR, making it a viable candidate for practical application as a PEMFC cathode electrode.

Image-based 3D characterization and reconstruction of heterogeneous battery electrode microstructure

There is a constant need for improvement of lithium-ion batteries (LIB), in particular, charge/discharge time, capacity, and safety to fulfil the increasing performance requirements. The performance of LIB materials is heavily dependent on their 3D microstructural characteristics. Physics-based 3D microstructure models that resolve the microstructural characteristics of all phases in a porous electrode are critical for quantifying the interplay between battery microstructure and performance. In this work, we employed a machine-learning algorithm to segment the active particles from previously published tomographic data obtained for an inhomogeneous porous microstructure of the LIB cathode electrode. We performed geometric characterization analysis using the segmented data, extracting the particle size distribution, porosity, tortuosity, and the connectivity of the particle system. We also present a methodology for stochastic reconstruction of electrode microstructure which is statistically equivalent to the empirical microstructure in terms of geometric characteristics. We use spherical harmonics to accurately represent the non-spherical particle morphology and resolve the contact between the particles. The stochastic reconstruction technique proposed herein enables generation of virtual microstructure designs beyond the limitations of empirical datasets. The methods developed in this work are presented via open source.

Hollow sphere of heterojunction (NiCu)S/NC as advanced anode for sodium-ion battery

Metal sulfide is considered as a potential anode for sodium-ion batteries (SIBs), due to the high theoretical capacity, strong thermodynamic stability and low-cost. However, their cycle capacity and rate performance are limited by the excessive expansion rate and low intrinsic conductivity. Herein, heterogeneous hollow sphere NiS-Cu9S5/NC (labeled as (NiCu)S/NC) based on Oswald ripening mechanism was prepared through a simple and feasible methodology. From a structural perspective, the hollow structure provides an expansion buffer and raises the electrochemical active area. In terms of electron/ion during the cycles, Na+ storage mechanism is optimized by NiS/Cu9S5 heterogeneous interface, which increases the storage sites and shortens the migration path of Na+. The formation of built-in electric field strengthens the electron/ion mobility. Based on the first principle calculations, it is further proved the formation of heterogeneous interfaces and the direction of electron flow. As the anode for SIBs, the synthesized (NiCu)S/NC delivers high reverse capacity (559.2 mA h g−1 at 0.5 A g−1), outstanding rate performance (185.3 mA h g−1 at 15 A g−1), long-durable stability (342.6 mA h g−1 at 4 A g−1 after 1500 cycles, 150.0 mA h g−1 at 10 A g−1 after 20,000 cycles with 0.0025% average attenuation rate). The matching cathode electrode Na3V2(PO4)3/C is assembled with (NiCu)S/NC for the full-battery that achieves high energy density (253.7 W h kg−1) and reverse capacity (288.7 mA h g−1). The present work provides a distinctive strategy for constructing electrodes with excellent capacity and stability for SIBs.

NiO/MoO2/MoO3 prepared by normal pulse voltammetry as cathode catalysts to investigate the properties of microbial electrolysis cells

AbstractBACKGROUNDA microbial electrolysis cell (MEC) is a bio‐hydrogen production device that uses electrochemically active bacteria on the anode combined with applied voltage to break down organic matter. However, the effects of element content on cathode reduction and cathode catalysts on bioanode activity remain unknown.RESULTSMEC cathodes with different content of Na2MoO4·2H2O (i.e. 0 g L−1 (Ni), 12.5 g L−1 (Ni–Mo 1), 25 g L−1 (Ni–Mo 2) and 37.5 g L−1 (Ni–Mo 3)) were fabricated by normal pulse voltammetry to evaluate the cathode performance. Nanoparticles of Ni electrode are crystalline NiO on the carbon fiber surface. Compared with the Ni electrode, the catalysts of Ni–Mo electrodes are composed of smaller crystalline NiO and amorphous Mo oxides. The results of electrochemical analysis confirmed that Ni–Mo 1 exhibited low exchange transfer resistance (148.72 Ω), high electrochemically active surface area and strong conductivity, resulting in optimal electrocatalysis performance. The newly fabricated electrodes are applied as cathodes in single‐chamber MEC reactors and inoculated with activated sludge from a municipal wastewater treatment plant. High peak current density determined using cyclic voltammetry of the bioanode indicated the strong electrochemical activity of electroactive bacteria in the bioanode of Ni–Mo 1. This is because the low resistance in the MECs could accelerate electron transfer and boost electrochemical reaction.CONCLUSIONSThe performance of cathodes with different Ni and Mo content in terms of electrochemical activity was evaluated. Consequently, the optimal cathode electrode in MECs was Ni–Mo 1. The obtained results reveal that the cathode affects the bioanode activity in MECs. © 2023 Society of Chemical Industry (SCI).

T-mode adsorption and photoelectrocatalysis degradation for acyclovir on CuMn2O4@WO3/g-C3N4 electrode

Abuse of antiviral drugs caused by overtreatment has attracted significant attention because of its widespread distribution in natural water. Here, we developed a novel CuMn2O4@WO3/g-C3N4 ((CMNW)CN) cathode electrode with CuMn2O4 (CMO) as electrocatalytic electrode and WO3/g-C3N4 (WCN) as photocatalytic electrode to realize the photoelectrocatalysis degradation for acyclovir in a Photo-Bio-Electro-Fenton (PBEF) system. The electrochemical performance, surface morphology and photoelectrocatalysis activity of the (CMNW)CN electrode were investigated, showing excellent redox performance and efficient electron transfer efficiency. Density functional theory (DFT) calculations confirmed that the CMO electrode adsorbed peroxymonosulfate (PMS) through a unique T-mode, increasing the photochemical activity and the ability of donor giving electrons of (CMNW)CN electrode, generating photogenerated electron-hole pairs under light conditions. Three proposed degradation pathways with eight degradation intermediates and the underlying reaction mechanism of acyclovir were identified in our research. Degradation efficiency of acyclovir in the PBEF reached 100% within 30 min, with high cycle stability. Our results demonstrated a new method for in-situ T-mode adsorption and photoelectrocatalysis degradation of acyclovir on (CMNW)CN electrode, especially the non-toxic effluents of PBEF proved the greenenvironment-friendly degradation process of drug residues.

Ultrathin PdCu Nanosheet as Bifunctional Electrocatalysts for Formate Oxidation Reaction and Oxygen Reduction Reaction.

The development of robust nonplatinum electrocatalysts to enhance the performance of formate oxidation reaction (FOR) and oxygen reduction reaction (ORR) is one of the key issues for the commercialization of direct formate fuel cells (DFFCs), but still challenging. Herein, a structurally controlled 3D flower-like PdCu nanosheet (NS) catalyst is synthesized by a method of oil bath reduction under mild conditions as a bifunctional electrocatalyst for DFFCs. Under the dual tuning on the composition and intermetallic phase, the PdCu nanosheet catalyst exhibits 8.67 times higher mass activity for anodic formate oxidation reaction than the commercial Pd/C. For the cathodic ORR, a positive shift half-wave potential is obtained for PdCu nanosheets exceeding Pt/C. Moreover, after a long-term stability test, the current density of the PdCu nanosheet catalyst for FOR and ORR can be well maintained with the least activity decay. When the PdCu NSs are used as optimized anode and cathode electrodes for DFFCs enable a peak power density as high as 53 mW cm-2 at room temperature, which is about 1.3 times higher than that of the commercial Pd/C and Pt/C as anode and cathode electrodes. This work provides a potential strategy to improve the catalytic performance of non-Pt-based nanocatalysts.

Sanitary landfill leachate treatment by aerated electrochemical Fenton process

The aerated electrochemical Fenton procedure was investigated as a viable treatment approach for electrolytic degradation and decolourization of sanitary landfill leachate. The optimization effects of initial pH, applied voltage, H2O2 concentration and combination of iron electrodes on detoxification were demonstrated by COD and colour removal from stabilized leachate, respectively. The study illustrates that, under the optimum experimental parameters voltage of 4.5 V, electrolysis time of 90 min, H2O2 dosage of 5 g/L, pH 3, 99% of chemical oxygen demand (COD) and 100% colour are removed from stabilized leachate, and the biodegradability ratio of the five-day biochemical oxygen demand (BOD5) to COD increases from 0.1 to 0.72. In addition, the pure catalytic metallic iron anode and cathode electrode used in the electrochemical Fenton process was first electro-oxidized to Fe2+ for use during the Fenton reaction, then with Fe3+ that was reverted back to Fe2+ under the applied electrochemical-magnetic field, resulting in the iron dissolution and regeneration circuit (Fe2+/Fe3+/Fe2+). Additionally, Fe2+/Fe3+ served as bridges for agglomerates to coalesce into big, closely packed particles for better filterability and sedimentation action. As a preparatory step for the biochemical treatment, this technology has been effectively used to treat stabilized landfill leachate containing toxic refractory recalcitrant organics on a large scale. Additionally, by estimating the scientific experiment with a regression model approach for the outcomes, RSM software was employed in order to standardize the ECF treatment process, significantly reducing the number of test cases and trials.

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials.

Improving the charge storage capacity and lifetime and charging/discharging efficiency of battery systems is essential for large-scale applications such as long-term grid storage and long-range automobiles. While there have been substantial improvements over the past decades, further fundamental research would help provide insights into improving the cost effectiveness of such systems. For example, it is critical to understand the redox activities of cathode and anode electrode materials and stability and the formation mechanism and roles of the solid-electrolyte interface (SEI) that forms at the electrode surface upon an external potential bias. The SEI plays a critical role in preventing electrolyte decay while still allowing charges to flow through the system while serving as a charge transfer barrier. While surface analytical techniques such as X-ray photoelectron (XPS), X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and atomic force microscopy (AFM) provide invaluable information on anode chemical composition, crystalline structure, and morphology, they are often performed ex situ, which can induce changes to the SEI layer after it is removed from the electrolyte. While there have been efforts to combine these techniques using pseudo-in situ approaches via vacuum-compatible devices and inert atmosphere chambers connected to glove boxes, there is still a need for true in situ techniques to obtain results with improved accuracy and precision. Scanning electrochemical microscopy (SECM) is an in situ scanning probe technique that can be combined with optical spectroscopy techniques such as Raman and photoluminescence spectroscopy methods to gain insights into the electronic changes of a material as a function of applied bias. This Review will highlight the potential of SECM and recent reports on combining spectroscopic measurements with SECM to gain insights into the SEI layer formation and redox activities of other battery electrode materials. These insights provide invaluable information for improving the performance of charge storage devices.