Comparative Investigation of Water-Based CMC and LA133 Binders for CuO Anodes in High-Performance Lithium-Ion Batteries.

Transition metal oxides are considered to be highly promising anode materials for high-energy lithium-ion batteries. While carbon matrices have demonstrated effectiveness in enhancing the electrical conductivity and accommodating the volume expansion of transition metal oxide-based anode materials in lithium-ion batteries (LIBs), achieving an optimized utilization ratio remains a challenging obstacle. In this investigation, we have devised a straightforward synthesis approach to fabricate CuO nano powder integrated with carbon matrix. We found that with the use of a sodium carboxymethyl cellulose (CMC) based binder and fluoroethylene carbonate additives, this anode exhibits enhanced performance compared to acrylonitrile multi-copolymer binder (LA133) based electrodes. CuO@CMC electrodes reveal a notable capacity ~1100 mA h g-1 at 100 mA g-1 following 170 cycles, and exhibit prolonged cycling stability, with a capacity of 450 mA h g-1 at current density 300 mA g-1 over 500 cycles. Furthermore, they demonstrated outstanding rate performance and reduced charge transfer resistance. This study offers a viable approach for fabricating electrode materials for next-generation, high energy storage devices.

Photothermal Enhancement of Prussian Blue Cathodes for Li-Ion Batteries.

Photoenhanced batteries, where light improves the electrochemical performance of batteries, have gained much interest. Recent reports suggest that light-to-heat conversion can also play an important role. In this work, we study Prussian blue analogues (PBAs), which are known to have a high photothermal heating efficiency and can be used as cathodes for Li-ion batteries. PBAs were synthesized directly on a carbon collector electrode and tested under different thermally controlled conditions to show the effect of photothermal heating on battery performance. Our PBA electrodes reach temperatures that are 14% higher than reference electrodes using a blue LED, and a capacity enhancement of 38% was achieved at a current density of 1600 mA g-1. Additionally, these batteries show excellent cycling stability with a capacity retention of 96.6% in dark conditions and 94.8% in light over 100 cycles. Overall, this work shows new insights into the effects leading to improved battery performance in photobatteries.

Advances in Electrochemical Liquid-Phase Transmission Electron Microscopy for Visualizing Rechargeable Battery Reactions.

This review presents an overview of the application of electrochemical liquid-phase transmission electron microscopy (ELP-TEM) in visualizing rechargeable battery reactions. The technique provides atomic-scale spatial resolution and real-time temporal resolution, enabling direct observation and analysis of battery materials and processes under realistic working conditions. The review highlights key findings and insights obtained by ELP-TEM on the electrochemical reaction mechanisms and discusses the current limitations and future prospects of ELP-TEM, including improvements in spatial and temporal resolution and the expansion of the scope of materials and systems that can be studied. Furthermore, the review underscores the critical role of ELP-TEM in understanding and optimizing the design and fabrication of high-performance, long-lasting rechargeable batteries.

Rapid measurement of bacterial contamination in water: A catalase responsive-electrochemical sensor.

The present study describes the development of a potentiometric sensor for microbial monitoring in water based on catalase activity. The sensor comprises a MnO2-modified electrode that responds linearly to hydrogen peroxide (H2O2) from 0.16 M to 3.26 M. The electrode potential drops when the H2O2 solution is spiked with catalase or catalase-producing microorganisms that decompose H2O2. The sensor is responsive to different bacteria and their catalase activities. The electrochemical sensor exhibits a lower limit of detection (LOD) for Escherichia coli at 11 CFU/ml, Citrobacter youngae at 12 CFU/ml, and Pseudomonas aeruginosa at 23 CFU/ml. The sensor shows high sensitivity at 3.49, 3.02, and 4.24 mV/cm2dec for E. coli, C. youngae, and P. aeruginosa, respectively. The abiotic sensing electrode can be used multiple times without changing the response potential (up to 100 readings) with a shelf-life of over six months. The response time is a few seconds, with a total test time of 5 min. Additionally, the sensor effectively tested actual samples (drinking and grey water), which makes it a quick and reliable sensing tool. Therefore, the study offers a promising water monitoring tool with high sensitivity, stability, good detection limit, and minimum interference from other water contaminants.

Applications of electron microscopic observations to electrochemistry in liquid electrolytes for batteries.

Herein, we review notable points from observations of electrochemical reactions in a liquid electrolyte by liquid-phase electron microscopy. In situ microscopic observations of electrochemical reactions are urgently required, particularly to solve various battery issues. Battery performance is evaluated by various electrochemical measurements of bulk samples. However, it is necessary to understand the physical/chemical phenomena occurring in batteries to elucidate the reaction mechanisms. Thus, in situ microscopic observation is effective for understanding the reactions that occur in batteries. Herein, we focus on two methods, of the liquid phase (scanning) transmission electron microscopy and liquid phase scanning electron microscopy, and summarize the advantages and disadvantages of both methods.

Targeted synthesis of a metal-free thiadiazolate based nitrogen and sulfur rich porous organic polymer for an unprecedented hydrogen evolution in the electrochemical water splitting.

Water splitting is a long-standing quest to material research for mitigating the global energy crisis. Despite high efficiency shown by several high cost noble metal containing electrocatalysts in the water splitting reaction, scientists are focused on alternate metal-free carbon or polymer based materials with comparable activity to make the process economical. In this article, we have strategically designed a noble metal-free thiadiazole (TDA) and triazine (Trz) linked porous organic polymer (TDA-Trz-POP) having N- and S-rich surface. Powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), solid state 13C magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopic (XPS) analyses have been performed to predict its probable framework structure. This scrunch paper type TDA-Trz-POP shows an extravagant potential for the hydrogen evolution reaction (HER) with a low overpotential (129.2 mV w.r.t. RHE for 10 mA cm-2 current density) and low Tafel slope (82.1 mV deg-1). Again, this metal-free catalyst shows oxygen evolution reaction (OER) at 410 mV overpotential w.r.t RHE for 10 mA cm-2 current density with a lower Tafel slope of 104.5 mV deg-1. This bifunctional activity was further tested in two electrodes set-up under different pH conditions. The porosity seems to be a blessing in the electrocatalytic performance of this metal-free electrocatalyst material. Further, the mystery behind the activity of both HER and OER has been resolved through the density functional theory (DFT) analysis. This work provides an insight to the material scientists for low cost, metal-free material design for the efficient water splitting reaction.

Mechanistic Insight into Electrode Processes by Operando Visualization of Interfacial pH Using Fluorescent Nanosensors.

Operando visualization of interfacial pH is crucial, yet challenging in electrochemical processes. Herein, we report the fabrication and utilization of ratiometric, fluorescent pH-sensitive nanosensors for operando quantification of fast-dynamic, interfacial pH changes in electrochemical processes and environments where unprotected fluorescent dyes would be degraded. Spatio-temporal pH changes were detected using an electrochemically coupled laser scanning confocal microscope (EC-LSCM) during the electrocoagulation treatment of model and field samples of oil-sands-produced water. Operando visualization of interfacial pH provided new insights into the electrode processes, including ion speciation, electrode fouling, and Faradaic efficiency. We provide compelling evidence that formed metal complexes precipitate at the edge of the pH boundary layer and that there is a strong coupling between the thickness of the interfacial pH layer and the electrode fouling. Furthermore, these findings provide a powerful pathway for optimizing the operating conditions, minimizing electrode passivation, and enhancing the efficiency of electrochemical processes, e.g., electrocoagulation, flow batteries, capacitive deionization, and electrolyzes.

Effect of polarity reversal on floc formation and rheological properties of a sludge formed by the electrocoagulation process.

Anode fouling is one of the key limiting factors to the widespread application of electrocoagulation (EC) for treatment of different types of contaminated water. Promising mitigation strategy to fouling is to operate the process under polarity reversal (PR) instead of direct current (DC). However, the PR operation comes at the cost of process complexity due to the alternation of electrochemical and chemical reactions. In this study, we systematically investigated the link between evolving fouling layer during DC and PR close to iron and aluminum electrodes and morphological and rheological properties of the formed sludge. By operando visualization of EC process, we demonstrate that during PR operation, precipitation of the iron and aluminum species occurs close to the anode interface, resulting in flocs with higher porosity and lower density than those formed under DC conditions. However, rheological investigation revealed that the PR conditions resulted in a sludge with more pronounced solid-like signature, but this enhancement in its viscoelastic properties is closely related to a period of the current's polarity reversal. We attribute this unexpected result to higher shear rate and collision of particles during PR conditions.

Recent catalytic applications of MXene-based layered nanomaterials.

The urgent issues related to the catalytic processes and energy applications have accelerated the development of hybrid and smart materials. MXenes are a new family of atomic layered nanostructured materials that require considerable research. Tailorable morphologies, strong electrical conductivity, great chemical stability, large surface-to-volume ratios, tunable structures, among others are some significant characteristics that make MXenes appropriate for various electrochemical reactions, including dry reforming of methane, hydrogen evolution reaction, methanol oxidation reaction, sulfur reduction reaction, Suzuki-Miyaura coupling reaction, water-gas shift reaction, and so forth. MXenes, on the other hand, have a fundamental drawback of agglomeration, as well as poor long-term recyclability and stability. One possibility for overcoming the restrictions is the fusion of nanosheets or nanoparticles with MXenes. Herein, the relevant literature on the synthesis, catalytic stability and reusability, and applications of several MXene-based nanocatalysts are deliberated including the merits and cons of the newer MXene-based catalysts.

Recent Progress in Metal Phosphorous Chalcogenides: Potential High-Performance Electrocatalysts.

Since the discovery of graphene, research on the family of 2D materials has been a thriving field. Metal phosphorous chalcogenides (MPX3 ) have attracted renewed attention due to their distinctive physical and chemical properties. The advantages of MPX3 , such as tunable layered structures, unique electronic properties, thermodynamically appropriate band alignments and abundant catalytic active sites on the surface, make MPX3 material great potential in electrocatalysis. In this review, the applications of MPX3 electrocatalysts in recent years, including hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction, are summarized. Structural regulation, chemical doping and multi-material composite that are often effective and practical research methods to further optimize the catalytic properties of these materials, are introduced. Finally, the challenges and opportunities for electrocatalytic applications of MPX3 materials are discussed. This report aims to advance future efforts to develop MPX3 and related materials for electrocatalysis.

The Use of Redox Mediators in Electrocatalysis and Electrosynthesis.

Electrocatalysis and electrosynthesis, which convert the electrical energy and store them in the chemical forms, have been considered as promising technologies to utilize green renewable energy sources. Most of the studies focused on developing novel active molecules or advanced electrodes to improve the performance. However, the direct acquisition and electron transferring will be limited by the intrinsic characters of the electrodes. The introduce of redox mediators, which are served as the intermediate electron carriers or reservoirs without changing the final products, provide a unique approach to accelerate the electrochemical performance of these energy conversions. This review provides an overview of the recent development of electrocatalysis and electrosynthesis by using redox mediators, and provides a comprehensive discussion toward focusing on the principles and construction of these systems.

Versatile Janus Architecture for Electrocatalytic Applications.

Janus architectures have garnered great research efforts in recent years, leading to outstanding advances in electrocatalysis. Benefiting from the synergistic combination of their anisotropy which endows the manifestation of various co-existing electrochemical properties, and their compartmentalized structure that enables each functional domain to retain its inherent activity, with little to no interference from other domains, Janus architectures show great potential as exceptionally versatile electrocatalysts to complement a plethora of electrocatalytic processes. Thus, coupled with the growing interest in Janus architectures for electrocatalysis, it is imperative to investigate and reconsider their design strategies and future directions.

Determining the hydronium pK[Formula: see text] at platinum surfaces and the effect on pH-dependent hydrogen evolution reaction kinetics.

Electrocatalytic hydrogen evolution reaction (HER) is critical for green hydrogen generation and exhibits distinct pH-dependent kinetics that have been elusive to understand. A molecular-level understanding of the electrochemical interfaces is essential for developing more efficient electrochemical processes. Here we exploit an exclusively surface-specific electrical transport spectroscopy (ETS) approach to probe the Pt-surface water protonation status and experimentally determine the surface hydronium pKa [Formula: see text] 4.3. Quantum mechanics (QM) and reactive dynamics using a reactive force field (ReaxFF) molecular dynamics (RMD) calculations confirm the enrichment of hydroniums (H3O[Formula: see text]) near Pt surface and predict a surface hydronium pKa of 2.5 to 4.4, corroborating the experimental results. Importantly, the observed Pt-surface hydronium pKa correlates well with the pH-dependent HER kinetics, with the protonated surface state at lower pH favoring fast Tafel kinetics with a Tafel slope of 30 mV per decade and the deprotonated surface state at higher pH following Volmer-step limited kinetics with a much higher Tafel slope of 120 mV per decade, offering a robust and precise interpretation of the pH-dependent HER kinetics. These insights may help design improved electrocatalysts for renewable energy conversion.

Metal-Based Aerogels Catalysts for Electrocatalytic CO2 Reduction.

General strategies for metal aerogel synthesis, including single-metal, transition-metal doped, multi-metal-doped, and nano-metal-doped carbon aerogel are described. In addition, the latest applications of several of the above-mentioned metal aerogels in electrocatalytic CO2 reduction are discussed. Finally, considering the possibility of future applications of electrocatalytic CO2 reduction technology, a vision for industrialization and directions that can be optimized are proposed.

Visualization of electrochemical reactions on microelectrodes using light-addressable potentiometric sensor imaging.

Visualization of the electrochemical reaction is essential for comprehensively understanding the electrochemical reaction mechanism and precisely characterizing dynamic electrochemical processes. Herein, we propose a simple device that combines light-addressable potentiometric sensor (LAPS) imaging and microelectrodes to serve as a general electroanalysis platform for the label-free sensing and imaging of electrochemical reactions. In this device, two microelectrodes are assembled on the LAPS chip. Electrochemical reactions occurring on the microelectrodes can be qualitatively and quantitatively observed and visualized using a LAPS chip that is sensitive to the reaction products. Validations were performed to monitor the effect of water electrolysis and potassium ferrocyanide oxidation surrounding the microelectrodes, respectively. We believe that this study will provide an excellent platform for the visualization and monitoring of electrochemical reactions and broaden the application scope of LAPS imaging to a general electroanalysis tool that is widely applicable in several fields.

Reliable electrochemical setup for in situ observations with an atmospheric SEM.

A novel setup for the in situ observation of electrochemical reactions in liquids through atmospheric scanning electron microscopy (SEM) is presented. The proposed liquid-phase electrochemical SEM system consists of a working electrode (WE) on an electrochemical chip and other two electrodes inserted into a liquid electrolyte; electrochemical reactions occurring at the WE are controlled precisely with an external potentiostat/galvanostat connected to the three electrodes. Copper deposition from a CuSO4 aqueous solution was conducted onto the WE, and simultaneous acquisition of nanoscale images and reliable electrochemical data was achieved with the proposed setup.

Electrocatalytic oxidation of aromatic amine (4-aminobiphenyl): Kinetics and transformation products with mechanistic approach.

Electrocatalytic oxidation (EO) of carcinogenic 4-aminobiphenyl (4-ABP) aromatic amine was performed using Ti-RuO2 anodes. Current (I), pH, electrolysis time (t), and 4-ABP initial concentration (Co ) were selected as EO parameters, and their effects on %4-ABP removal (R1 ) and energy consumed (R2 ) were studied. Experimental design, parameters optimization, and their interaction with responses R1 and R2 were performed using response surface methodology. At optimized parameters, %TOC removal and 4-BP mineralization current efficiency (%MCE) were assessed to evaluate the potential of Ti/RuO2 anodes towards 4-ABP mineralization. Simultaneous TOC and 4-ABP degradation kinetics were also studied to evaluate the competition in 4-ABP mineralization and degradation. Further, UPLC-Q-TOF-MS analysis was performed to identify the 4-ABP transformation products during the EO, and a mechanism describing the EO transformation was proposed. At optimum parameters (I = 1.2 A; pH = 4.0; t = 30 min; Co = 30 ppm), responses were found to be R1 = 60.25%; R2 = 2.49 kWh/g of 4-ABP removed. %TOC removal and %MCE were 52.4% and 34.2%, respectively. PRACTITIONER POINTS: 4-Aminobiphenyl electro-oxidation (EO) was explored using Ti/RuO2 anode. Achieved 34.2% mineralization current efficiency, 52.4% TOC and 61.3% TKN removal. Three electro-oxidation transformation products of 4-ABP were detected. 4-Aminobiphenyl was found degrading at ≈1.6 times higher rate than TOC A plausible EO transformation pathway and mechanism was proposed.

Low Temperature Nano Mechano-electrocatalytic CH4 Conversion.

Transforming natural resources to energy sources, such as converting CH4 to H2 and carbon, at high efficiency and low cost is crucial for many industries and environmental sustainability. The high temperature requirement of CH4 conversion regarding many of the current methods remains a critical bottleneck for their practical uptake. Here we report an approach based on gallium (Ga) liquid metal droplets, Ni(OH)2 cocatalysts, and mechanical energy input that offers low-temperature and scalable CH4 conversion into H2 and carbon. Mainly driven by the triboelectric voltage, originating from the joint contributions of the cocatalysts during agitation, CH4 is converted at the Ga and Ni(OH)2 interface through nanotribo-electrochemical reaction pathways. The efficiency of the system is enhanced when the reaction is performed at an increased pressure. The dehydrogenation of other nongaseous hydrocarbons using this approach is also demonstrated. This technology presents a possible low energy route for CH4 conversion without involving high temperature and harsh operating conditions.

A multifunctional and low-energy electrochemical membrane system for chemical-free regulation of solution pH.

A proper pH environment is essential for a wide variety of industries and applications especially related to water treatment. Current methods for pH adjustment including addition of acid/base and electrochemical processes demonstrate disadvantages associated with environment and energy. Here, we designed a multifunctional electrochemical membrane system (EMS) with one piece of filtration membrane inserted into an electrochemical cell. When electrical field was applied, OH- and H+ ions were produced from reduction and oxidation reactions at cathode and anode, respectively. The membrane posed a resistance for the transport of OH- and H+ ions and prevented their mixing in the cell. The EMS can be also operated in a filtration mode, which could simultaneously regulate permeate and feed pH and accomplish water filtration. In both non-filtration and filtration modes, EMS could achieve effective control of solution pH over a wide range by exerting different voltages without dosing any chemicals. Under the voltage of 1.2 V, the solution pH could reach and be maintained at 10.7 and 3.3 in cathodic and anodic channels, respectively. Furthermore, it was experimentally demonstrated that the EMS only consumed extremely low energy. This, together with membrane filtration in an integrated manner, highlights the huge potential of the EMS for applications in various water industries.

Solvent Degradation and Polymerization in the Li-Metal Battery: Organic-Phase Formation in Solid-Electrolyte Interphases.

The products of solvent polymerization and degradation are crucial components of the Li-metal battery solid-electrolyte interphase. However, in-depth mechanistic studies of these reactions are still scarce. Here, we model the polymerization of common lithium battery electrolyte solvents─ethylene carbonate (EC) and vinylene carbonate (VC)─near the anode surface. Being consistent with the molecular calculation, ab initio molecular dynamic (AIMD) simulations reveal fast solvent decompositions upon contact with the Li anode. Additionally, we assessed the thermochemical impacts of decarboxylation reactions as well as the lithium bonding with reaction intermediates. In both EC and VC polymerization pathways, lithium bonding demonstrated profound catalytic effects while different degrees of decarboxylation were observed. The VC polymerization pathways with and without ring-opening events were evaluated systematically, and the latter one which leads to poly(VC) formation was proven to dominate the oligomerization process. Both the decomposition and polymerization reactivities of VC are found to be higher than EC, while the cross-coupling between EC and VC has an even lower-energy barrier. These findings are in good agreement with experimental evidence and explanatory toward the enhanced performance of VC-added lithium-metal batteries.