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Electrochemical Double Layer Capacitors (EDLCs) with ionic liquid electrolytes outperform conventional ones using aqueous and organic electrolytes in energy density and safety. However, understanding the electrochemical behaviors of ionic liquid electrolytes under compressive/tensile strain is essential for the design of flexible EDLCs as well as normal EDLCs, which are subject to external forces during assembly. Despite many experimental studies, the compression/stretching effects on the performance of ionic liquid EDLCs remain inconclusive and controversial. In addition, there is hardly any evidence of prior theoretical work done in this area, which makes the literature on this topic scarce. Herein, for the first time, we developed an atomistic model to study the processes underlying the electrochemical behaviors of ionic liquids in an EDLC under strain. Constant potential non-equilibrium molecular dynamics simulations are conducted for EMIM BF4 placed between two graphene walls as electrodes. Compared to zero strain, low compression of the EDLC resulted in compromised performance as the electrode charge density dropped by 29%, and the performance reduction deteriorated significantly with a further increase in compression. In contrast, stretching is found to enhance the performance by increasing the charge storage in the electrodes by 7%. The performance changes with compression and stretching are due to changes in the double-layer structure. In addition, an increase in the value of the applied potential during the application of strain leads to capacity retention with compression revealed by the newly performed simulations. [ABSTRACT FROM AUTHOR]

The shortage of natural resources due to the progression of the human population and environmental pollution has become crucial concern topics to resolve. One of the best ways to resolve this is to develop renewable energy-based storage systems. Supercapacitors are emerging as promising storage systems via providing rapid charging/discharging and high power delivery, but there is a need to explore low-cost, environment-friendly, non-toxic, abundant, and biodegradable electrode materials for supercapacitors. In this regard, biopolymers are observed to be popular for storage applications as they are of high porosity, cost-effective, easily available, low-weight, and environment friendly and have biodegradability properties. The biopolymer-based electrode has a desirable morphology and high surface area and exhibits admirable electrochemical properties. The focus of this report is to highlight (i) the inclusive details of supercapacitors and their types along with strategies to improve their electrochemical performance, (ii) biopolymers and their types used for supercapacitor applications, (iii) various synthesis routes that could be adopted for designing electrode materials based on biopolymers for supercapacitors, and (iv) challenges and future scope of biopolymers as the electrode material in supercapacitor applications. The detailed study here in this report is found to be a topic of interest for the scientific community to fabricate and prepare low-cost, eco-friendly, high electrochemical performance exhibiting electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Nanocomposites containing mixed transition metal oxides demonstrate significant promise as materials for supercapacitors, specifically due to their enhanced surface area, synergistic effect of multiple metal cations, excellent electrical conductivity, and improved electrochemical properties. In this study, we synthesized a nanocomposite with a nanograss array morphology consisting of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 using an in-situ sol-gel method. For comparison, we synthesized a composite (CoFe 2 O 4 /Fe 3 O 4) without SnO 2. Through a systematic characterization employing various analytical techniques, we examined the structural, morphological, and textural attributes of the resulting composites. The results reveal that the phase percentages of CoFe 2 O 4 , SnO 2 , and Fe 3 O 4 were 38%, 33%, and 29% in the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite. Also, the nanograss array of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 is composed of nano-sized primary particles, while CoFe 2 O 4 /Fe 3 O 4 showed spherical-like nanoparticle morphology. The BET surface area of the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite was found to be seven times higher than that of CoFe 2 O 4 /Fe 3 O 4. We also evaluated the electrochemical performance of the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite as a cathode material for battery-type supercapacitors. The synergistic combination of SnO 2 and CoFe 2 O 4 /Fe 3 O 4 in the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 electrode resulted in a high specific capacity of 465C g−1 at 1 A g−1, which is 2.5 times higher than the CoFe 2 O 4 /Fe 3 O 4 electrode. Additionally, the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 electrode exhibited a remarkable rate capability of 87% at 10 A g−1 and excellent cyclic performance with 96% capacity retention after 5000 cycles. A hybrid supercapacitor was fabricated, featuring a cathode composed of a composite electrode consisting of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 and an anode comprising activated carbon (AC). This fabricated SnO 2 /CoFe 2 O 4 /Fe 3 O 4 //AC HSC device configuration exhibited impressive performance characteristics, boasting a notable energy density of 38.4 Wh kg−1 at 1468.2 W kg−1. These findings underscore the significant impact of SnO 2 on the physio/electrochemical properties of the CoFe 2 O 4 /Fe 3 O 4 composite. The outstanding electrochemical performance of this electrode underscores its potential for application in next-generation hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

Mesoporous silica materials (MSMs) are widely used materials in many applications due to their diverse pore structures. However, the electrical conductivity of MSMs is poor which limits their use in electrochemical applications. In this study, widely used MSMs of different structural properties such as MCM-41, MCM-48, SBA-15, and SBA-16 were synthesized and reinforced with graphene oxide (GO) to obtain conductive composite supports for enzyme immobilization. MSMs were first synthesized using a hydrothermal method and characterized by Fourier-transform infrared spectroscopy, X-ray crystallography, scanning electron microscopy/energy dispersive X-ray, and MAPPING techniques. Aqueous dispersion of GO:MSM composites were prepared with as-synthesized materials and coated on screen-printed electrodes (SPE). The best composites were chosen based on their electroanalytical performance. Glucose oxidase (GOx) was then immobilized on modified SPEs using a simple drop-casting method to produce enzymatic electrodes. The electroanalytical performance of the enzymatic electrodes was investigated using different glucose concentrations to demonstrate biocatalytic activity. Stability tests were performed using intraday and interday measurements which revealed that SPE/GO:MCM-41/GOx electrode showed a more stable performance (3-folds) than SPE/GO/GOx electrode. This study presents an investigation of MSM mixed with GO in enzymatic electrochemical systems providing insight into the use of such materials to preserve enzyme activity. [ABSTRACT FROM AUTHOR]

In this work, transition metal oxide (Bi2WO6) and metal organic framework (MIL-53(Al)) were used to prepare a composite. The MIL-53(Al) and Bi2WO6 powder were synthesized through hydrothermal route and the MIL-53(Al)/Bi2WO6 composite was prepared through impregnation technique. FESEM-EDX, XRD, FTIR and multi-point BET were used to characterize the MIL-53(Al), Bi2WO6 and composite. Electrochemical study was performed by employing a potentiostat and a 3-electrode cell, where platinum wire taken as counter electrode, active material-coated graphitic carbon felt as the working electrode and Ag/AgCl taken as reference electrode. MIL-53(Al) and Bi2WO6 were tested separately to determine the electrochemical efficiency, and it was found through galvanostatic charge–discharge method that they both have low energy densities when compared to the composite. The energy density of the composite was found to increase due to the characteristic changes resulting from the combination of MIL-53(Al) and Bi2WO6. Compared with the pristine MIL-53(Al) and Bi2WO6, the composite has exhibited higher specific capacitance of 554 F g−1 at 0.5 A g−1 and the lowest equivalent series resistance (ESR) resistance was obtained in electrochemical impedance spectroscopy study, which confirms that the MIL-53(Al)/Bi2WO6 hybrid has improved its performance as electrode material for supercapacitor application. [ABSTRACT FROM AUTHOR]

In this study, S-CCO@Co(OH)2 ('CCO' representing CuCo2O4/Cu2O; 'S-'representing sulfur doping) was synthesized by hydrothermal method followed by electrodeposition. The multiple effects of S doping were studied by S doping and constructing 3D core–shell structure. S doping induced the reduction of Cu2+ and Co3+ to Cu+ and Co2+, respectively. Also, S partially replaces O and creates oxygen vacancies, which increases a number of active sites for the redox reaction enhancing the redox reaction activity. After the electrodeposition, S–Co bond is formed between the Co(OH)2 shell and the S-CCO core, which suggests a synergistic effect between S doping and core–shell structure. The formation of S–Co bond is conducive to electron and ion transport, thus improving electrochemical performance. After modification, the specific capacitance of S-CCO@Co(OH)2 is 4.28 times higher than CCO, up to 1730 Fg−1. Furthermore, the assembled S-CCO@Co(OH)2//activated carbon supercapacitor exhibits an energy density of 83.89 Whkg−1 at 848.81 Wkg−1 and a retention rate of 98.48% after 5000 charge and discharge cycles. Therefore, S doping and its mutual effect with the utilization of the core–shell structure considerably enhanced the electrochemical performance of the CCO-based electrodes, endowing its potential in further application. [ABSTRACT FROM AUTHOR]

Coal fly ash (FA), an aluminum silicate by-product and environmental pollutant which is generated during the combustion of coal in coal-fired power stations, was used as an electrode modifier for the determination of Cd(II) in aqueous solutions. In this work, graphite/polyurethane-based composites containing different amounts of FA were prepared and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) thermogravimetry (TGA), and derivative thermogravimetry (DTG). The graphite/polyurethane composite electrodes (GPUE), with and without FA modifier, were evaluated with regard to their performance as voltammetric electrodes in the determination of metallic cations, using Cd(II) as a probe. After optimizing solution and instrumental parameters affecting the peak current, a differential pulse anode stripping voltammetry (DPASV) procedure was developed for GPUE modified with 5% FA (m/m), resulting in a linear response for Cd(II) from 2.0 x 10−7 to 1.0 x 10−6 mol L−1 with a detection limit (LOD) of 6.6 x 10−8 mol L−1. Cd(II) was added to natural water samples and determined at the 10−7 mol L−1 level with a mean recovery of 99%. It was also extracted from exhausted rechargeable Ni-Cd batteries and diluted to ca. 0.2 µmol L−1 and determined with the same electrode, with recoveries of 98.7% when compared to FAAS. These results serve as a proof of concept that FA is a useful electrode modifier. [ABSTRACT FROM AUTHOR]

Liquid metal (LM) is widely used in flexible electronic devices due to its excellent metallic conductivity and ductility. However, the fabrication of LM flexible strain sensors with high sensitivity and linearity is still a huge challenge, since the resistance of LM does not change much with strain. Here, a highly sensitive and linear fully flexible strain sensor with a resistive sensing function is proposed. The sensor comprises an Fe-doped liquid metal (Fe-LM) electrode for enhanced performance. The design and manufacturing of flexible strain sensors are based on the technology of controlling surface wettability by femtosecond laser micro/nano-processing. A supermetalphobic microstructure is constructed on a polydimethylsiloxane (PDMS) substrate to achieve the selection adhesion of Fe-LM on the PDMS substrate. The Fe-LM-based flexible strain sensor has high sensitivity and linearity, a gauge factor (GF) up to 1.18 in the strain range of 0–100%, excellent linearity with an R2 of 0.9978, a fast response time of 358 ms, and an excellent durability of more than 2400 load cycles. Additionally, the successful monitoring of human body signals demonstrates the potential of our developed flexible strain sensor in wearable monitoring applications. [ABSTRACT FROM AUTHOR]

Heavy metal poisoning has a life-threatening impact on the human body to aquatic ecosystems. This necessitates designing a convenient green methodology for the fabrication of an electrochemical sensor that can detect heavy metal ions efficiently. In this study, boron (B) and nitrogen (N) co-doped laser-induced porous graphene (LIGBN) nanostructured electrodes were fabricated using a direct laser writing technique. The fabricated electrodes were utilised for the individual and simultaneous electrochemical detection of lead (Pb2+) and cadmium (Cd2+) ions using a square wave voltammetry technique (SWV). The synergistic effect of B and N co-doping results in an improved sensing performance of the electrode with better sensitivity of 0.725 µA/µM for Pb2+ and 0.661 µA/µM for Cd2+ ions, respectively. Moreover, the sensing electrode shows a low limit of detection of 0.21 µM and 0.25 µM for Pb2+ and Cd2+ ions, with wide linear ranges from 8.0 to 80 µM for Pb2+ and Cd2+ ions and high linearity of R2 = 0.99 in case of simultaneous detection. This rapid and facile method of fabricating heteroatom-doped porous graphene opens a new avenue in electrochemical sensing studies to detect various hazardous metal ions. [ABSTRACT FROM AUTHOR]

Intense pulsed light was investigated for partial photoreduction of AgCl in a poly(vinyl butyral) matrix to obtain a Ag/AgCl reference membrane. The membrane was deposited on both glassy carbon and inkjet‐printed silver electrodes giving all‐solid‐state reference electrodes. Regardless of the electrode material, a sufficient potential stability was obtained in a broad concentration range of various salt solutions. Long‐term potential stability was significantly improved with inkjet‐printed silver electrical contacts. The electroanalytical performance of inkjet‐printed electrodes was successfully demonstrated in potentiometric and amperometric systems. [ABSTRACT FROM AUTHOR]

Direct management and assessment of metal film properties applied to polymer microneedle (MN) biosensors remains difficult due to constraints inherent to their morphology. By simplifying the three-dimensional structure of MNs and adjusting the deposition time, different thicknesses of Au films were deposited on the UV-cured polymer planar and MN substrates. Several properties relevant to the biosensing of the Au films grown on the polymer surfaces were investigated. The results demonstrate the successful deposition of pure and stable Au nanoparticles onto the surface of UV-curable polymer materials. Initially, Au islands formed within the first minute of deposition; however, as the sputtering time extended, these islands transformed into Au nanoparticle films and disappeared. The hydrophilicity of the surface remains unchanged, while the surface resistance of the thin film decreases with increasing thickness, and the adhesion to the substrate decreases as the thickness increases. In short, a sputtering time of 5–6 min results in Au films with a thickness of 100–200 nm, which exhibit exceptional comprehensive biosensing performance. Additionally, MNs made of Au/UV-curable polymers and produced using magnetron sputtering maintain their original shape, enhance their mechanical characteristics, and gain new functionalities. The Au/UV-curable polymer MNs exhibited remarkable electrode performance despite being soaked in a 37 °C PBS solution for 14 days. These discoveries have important implications in terms of decreasing the dependence on valuable metals in MN biosensors, lowering production expenses, and providing guidance for the choice and design of materials for UV-curable polymer MN metallization films. [ABSTRACT FROM AUTHOR]

Promising metal hydride electrode performance of LaNi4.5Co0.4Al0.1, prepared by induction melting and next hydrogen-induced decrepitation, was proven in the present study. Both the composition and microstructure of the electrode material were found to be responsible for its reliable hydrogen capacity and cycle stability. After prolonged exposure to air, the alloys retain their high hydrogen sorption characteristics, revealing only 10% capacity reduction. The gas phase hydriding of the alloys confirms the hydrogen capacity obtained under electrochemical conditions. Furthermore, the influence of C, Co, and Co3O4 additions to the LaNi5-based alloy on the hydrogen electrode performance was also elucidated. The highest capacity of 300 mAh g−1, remaining constant for 20 cycles, was obtained for LaNi4.5Co0.4Al0.1 + 15 mg Co3O4. This material maintains excellent capacity also at high current densities, making it a suitable electrode material in Ni/MH batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new 3-D bi-metal organic framework was synthesized by hydrothermal method. • After pyrolysis, binary metal oxides were prepared and applied to the anode materials of LIBs. • CeCo-700 has the highest specific capacity of 952 mAh g−1 at 100 mA g−1 after 150 cycles. Precursor method is a well-known technology for preparing certain functional materials. In this work, a novel 3d-4f bimetallic organic framework, denoted as 45MCeCo (45 M representing 4,5-imidazole dicarboxylic acid), was successfully synthesized via a hydrothermal technique. The compound thus obtained has the molecular formula of C 10 H 11 CeCoN 4 O 12. By meticulously controlling the amounts of the experimental materials, it was feasible to prepare flower-like crystals possessing identical single crystal structures and significantly larger specific surface areas. As a precursor for electrode materials, this structure underwent calcination at different temperatures to prepare Co 3 O 4 /CeO 2 composites with in situ composite heterostructures. Post-electrochemical tests revealed that CeO 2 remains unreactive across all potentials, thereby contributing to the stabilization of the electrode material structure. In contrast, Co 3 O 4 participated in redox reactions to provide a specific capacity to the sample. In addition, when comparing the performance of the electrode material under different calcination conditions, it became evident that the material exhibited optimal electrochemical performance when subjected to a temperature of 700 °C for 2 h. [ABSTRACT FROM AUTHOR]

This study reports the preparation of binary metal sulfide heterostructure enclosed in functional carbon layer (termed CoS 2 /SnS 2 @SC) as anodes for PIBs by a synchronous vulcanization process with chemical vapor deposition (CVD), which achieves high electrochemical and kinetic performance and has far-reaching implications for the study of potassium storage devices. [Display omitted] Metallic sulfides are currently considered as ideal anode materials for potassium-ion batteries by virtue of their high specific capacities. However, their low intrinsic electronic conductivity, large volume variation and dissolution of polysulfides in electrochemical reactions hinder their further development toward practical applications. Here, we propose an effective structural design strategy by encapsulating CoS 2 /SnS 2 in sulfur-doped carbon layers, in which internal voids are created to relieve the strain in the CoS 2 /SnS 2 core, while the sulfur-doped carbon layer serves to improve the electron transport and inhibit the dissolution of polysulfides. These features enable the as-designed anode to deliver a high specific capacity (520 mAh/g at 0.1 A/g), a high rate capability (185 mA h g−1 at 10 A/g) and lifespan (0.016 % capacity loss per cycle up to 1500 cycles). Our comprehensive electrochemical characterization reveals that the heterostructure of CoS 2 /SnS 2 not only promotes charge transfer at its interfaces, but also enhances the rate of K+ diffusion. Additionally, potassium-ion capacitors based on this novel anode are able to attain an energy density up to 162 Wh kg−1 and ∼ 96 % capacity retention after 3000 cycles at 10 A/g. The demonstrated design rule combining morphological and structural engineering strategies sheds light on the development of advanced electrodes for high performance potassium-based energy storage devices. [ABSTRACT FROM AUTHOR]

Hierarchical porous carbon materials have received significant attention for application in catalytic water splitting because of their high efficiency, cost-effectiveness, and biocompatibility. In this study, laser-induced graphene (LIG) was fabricated on a carbon film- (CF-) type substrate for an efficient hydrogen evolution reaction (HER). The LIG-CF electrode was fabricated via laser-induced graphitization on a commercial polyimide (PI) film, followed by the pyrolysis of the LIG on the PI film (LIG-PI). During pyrolysis, the microscopic and material properties of the LIG remained intact, as verified through various characterizations. The as-prepared all-carbon electrode was then utilized as an electrode for the HER study in a 1.0 M KOH electrolyte and compared with LIG-PI and Pt electrodes. In the HER experiments, the optimized LIG-CF electrode exhibited excellent catalytic performance with zero-onset potential, and the potentials required to achieve high current densities of 10 and 20 mA/cm2 were 134 and 139 mV (vs. reversible hydrogen electrode (RHE)), respectively. The excellent performance of the LIG-CF electrode originates from the hierarchical porous structure of the LIG material, which serves as an electrochemically active site, and carbon substrate that facilitates the fast transport of ions at the electrode/electrolyte interface. Additionally, the carbon substrate shortens the transportation length of electrons which played a significant role for the enhanced performance of the LIG-CF electrode. [ABSTRACT FROM AUTHOR]

Clean and efficient hydrogen fuel as the future energy source for decarbonizing and establishing a sustainable carbon-neutral economy is highly attractive. Notable progress in hydrogen production through water splitting has been conducted to achieve zero carbon emissions, safety, and high product purity. Despite advancements, challenges like a significant large energy barrier with high cost associated with water splitting still exist. Efficient electrocatalysts have been designed to address the challenges of water splitting. Those catalysts aim to reduce energy barriers and costs associated with the process. Nevertheless, there are still challenges in promoting the industrialization of electrocatalytic water splitting. This review discusses the latest progress in water electrolysis, incorporating experimental evidence from in-situ spectroscopic surveys and computational analyses to provide a mechanistic understanding of hydrogen and oxygen evolution reactions. Various evaluation metrics and essential strategies are highlighted for designing and fabricating efficient electrocatalysts, including alloying, morphological engineering, interface construction, defect engineering, and strain engineering. This work aims to provide a knowledge-guided design in fundamental science, offering insights that could inspire technical engineering developments to build efficient electrocatalysts for water splitting. [Display omitted] • Essential parameters and evaluation metrics of electrode performances are discussed. • Crucial strategies for improving HER and OER works are summarized. • Alloying materials with a high-entropy configuration improves the long-term stability. • Porous materials with edges are essential for designing highly efficient electrodes. • Strain engineering on electrode surface modification shows a great promising strategy. [ABSTRACT FROM AUTHOR]

Developing high‐performance carbonaceous anode materials for sodium‐ion batteries (SIBs) is still a grand quest for a more sustainable future of energy storage. Introducing sulfur within a carbon framework is one of the most promising attempts toward the development of highly efficient anode materials. Herein, a microporous sulfur‐rich carbon anode obtained from a liquid sulfur‐containing oligomer is introduced. The sodium storage mechanism shifts from surface‐controlled to diffusion‐controlled at higher synthesis temperatures. The different storage mechanisms and electrode performances are found to be independent of the bare electrode material's interplanar spacing. Therefore, these differences are attributed to an increased microporosity and a thiophene‐rich chemical environment. The combination of these properties enables extending the plateau region to higher potential and achieving reversible overpotential sodium storage. Moreover, in‐operando small‐angle X‐ray scattering (SAXS) reveals reversible electron density variations within the pore structure, in good agreement with the pore‐filling sodium storage mechanism occurring in hard carbons (HCs). Eventually, the depicted framework will enable the design of high‐performance anode materials for sodium‐ion batteries with competitive energy density. [ABSTRACT FROM AUTHOR]

The manufacturing process of Lithium‐ion battery electrodes directly affects the practical properties of the cells, such as their performance, durability, and safety. While computational physics‐based modeling has been proven as a very useful method to produce insights on the manufacturing properties interdependencies as well as the formation of electrode microstructures, their high computational costs prevent their direct utilization in electrode optimization loops. In this work, a novel time‐dependent deep learning (DL) model of the battery electrodes manufacturing process is reported, demonstrated for calendering of nickel manganese cobalt (NMC111) electrodes, and trained with time‐series data arising from physics‐based Discrete Element Method (DEM) simulations. The DL model predictions are validated by comparing evaluation metrics (e.g., mean square error (MSE) and R2 score) and electrode functional metrics (contact surface area, porosity, diffusivity, and tortuosity factor), showing very good accuracy with respect to the DEM simulations. The DL model can remarkably capture the elastic recovery of the electrode upon compression (spring‐back phenomenon) and the main 3D electrode microstructure features without using the functional descriptors for its training. Furthermore, the DL model has a significantly lower computational cost than the DEM simulations, paving the way toward quasi‐real‐time optimization loops of the 3D electrode architecture predicting the calendering conditions to adopt in order to obtain the desired electrode performance. [ABSTRACT FROM AUTHOR]

To solve the problem of renewable energy generation fluctuation, water splitting for hydrogen generation is proposed, which can store renewable energy as hydrogen energy. Low overpotential cathode materials can effectively reduce the cost of hydrogen production. Here, a new NiMo/NMF electrode was prepared using a hydrothermal coupled H 2 reduction method. Three-dimensional NiMo nanorod arrays were constructed by modulating the ion dissolution and surface epitaxial growth process of the electrode substrate. The influence of different hydrothermal reaction and H 2 reduction conditions on the electrochemical performance of the electrode was investigated. Under optimum preparation conditions, the NiMo/NMF electrode exhibits a extremely low overpotentials of 158 mV at 500 mA cm-2 (30% wt. KOH alkaline medium), which can serve for preparing high efficiency and economy electrodes by in-situ integration of high active components on metal foam substrate. The NiMo/NMF electrode is a high-performance electrocatalytic cathode material with great prospects for industrial applications. • Water splitting for hydrogen generation is proposed for renewable hydrogen energy. • We made a low-overpotential NiMo/NMF electrode via hydrothermal coupled H 2 reduction. • The electrochemical performance of the NiMo/NMF electrode was investigated. • Different hydrothermal and H 2 reduction temperatures and times were explored. • The NiMo/NMF electrode exhibits a remarkable HER activity with low overpotentials. [ABSTRACT FROM AUTHOR]

The availability of self-supported porous electrodes with excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic activity has been an important cornerstone for the performance of alkaline water electrolysers (AWEs). In addition, the management of heat and two-phase flow during ion/electron transfer in porous electrodes poses significant challenges to the stable operation of AWE electrolysers. In this work, a two-dimensional non-isothermal multiphysical model considering two-phase flow, mass, heat and charge transfer processes is developed based on COMSOL Multiphysics and well validated with reliable experimental data. The model exhibits excellent agreement with actual electrolyser operating voltages between 323–343 K, and the relative error is within acceptable 2.2% even at high current densities up to 1.5 A cm−2. In addition, the electrode kinetic data obtained based on standard three-electrode experiments allow the model to predict the corresponding HER and OER overpotentials of the porous electrodes with great accuracy, as well as to obtain the distribution of temperature and ionic species inside the porous electrodes under various volumetric flow rates and current densities. This work provides a practical and reliable guide for the design of porous electrodes and the performance enhancement of electrolysers from both experimental and simulation perspectives. • Non-isothermal multiphysical model for zero-gap alkaline water electrolyser is developed based on reliable experimental data. • The model is more accurate than traditional ones for electrode overpotentials and single-cell I–V curves over 0.1–1.5A cm−2. • The temperature rise due to heat accumulation is almost linearly correlated with the current density. • The ohmic overpotential of an electrolyser operating at high current densities accounts ＞ 50% of the thermal contribution. [ABSTRACT FROM AUTHOR]

Microheaters are used in several applications, including medical diagnostics, synthesis, environmental monitoring, and actuation. Conventional microheaters rely on thin-film electrodes microfabricated in a clean-room environment. However, low-cost alternatives based on conductive paste electrodes fabricated using printing techniques have started to emerge over the years. Here, we report a surprising effect that leads to significant electrode performance improvement as confirmed by the thorough characterization of bulk, processed, and conditioned samples. Mixing silver ink and PVA results in the solubilization of performance-hindering organic compounds. These compounds evaporate during heating cycles. The new electrodes, which reach a temperature of 80 °C within 5 min using a current of 7.0 A, display an overall 42% and 35% improvement in the mechanical (hardness) and electrical (resistivity) properties compared to pristine silver ink electrodes. To validate our results, we use the composite heater to amplify and detect parasite DNA from Trypanosoma brucei, associated with African sleeping sickness. Our LAMP test compares well with commercially available systems, confirming the excellent performance of our nanocomposite heaters. Since their fabrication relies on well-established techniques, we anticipate they will find use in a range of applications. [ABSTRACT FROM AUTHOR]

Polymer electrolyte was used as a medium for testing the performance of microband electrodes under conditions of linear diffusion. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments were performed in a highly viscous medium, where diffusion rates are much slower than in fluid solutions. The log i vs. log v (CV) or log i vs. log t (CA) relationships with the current equation confirmed the existence of such conditions, yielding slope values that were lower than the expected 0.5. This could indicate an impure linear diffusion profile, i.e., some contribution from radial diffusion (edge effects). However, the desired value of 0.5 was obtained when performing these tests in monomeric solvents of similar viscosities, such as glycerol or propylene glycol. These results led to the conclusion that the current equations, which are based on Fick's laws, may not be applicable for polymer electrolytes, where various obstructions to free diffusion result in a more complicated process than for monomeric solvents. [ABSTRACT FROM AUTHOR]

A pair of polyaniline (PANIs) samples was prepared from HCl or H2SO4 electrolytes containing 0.01 M of aniline, and then subjecting them to electropolymerization. The morphology, structure, and properties of the samples were characterized using scanning electron microscope, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The results demonstrate that the capacitance and morphology of the product depend exclusively on the reactive medium used. The PANI was used as a material electrode in a supercapacitor, and the electrochemical performance of the elaborated electrodes was evaluated using cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. The optimal results for the specific capacitance of the PANI films were achieved under a 5-mVs−1 scan rate, ranging from 410.35 F/g for the FTO/PANI-H2SO4 to 758.72 F/g for the FTO/PANI-HCl. [ABSTRACT FROM AUTHOR]

A matrix-type bismuth-moderated copper-sulfur electrode Bi-NiBx@CFS was prepared in-situ by mild electroless plating for efficient hydrogen production in alkaline seawater. The electrode possesses a "photothermal effect" equivalent to increasing the temperature of conventional electrolyte solution to 48 °C at the same conditions, and works stably for 150h without any performance degradation at industrial-grade current density. [Display omitted] • A highly active and stable catalytic electrode Bi-NiBx@CFS applied to electrolysis of alkaline seawater can be constructed by simple electroless plating. • The "photothermal effect" of the doped Bi materials with good photothermal properties achieves about 10 % improvement in the performance of the catalytic electrode at a current density of 10 mA cm−2. • The in-situ etched and firmly grown materials are suitable for industrialized large-scale applications, and Bi-NiBx@CFS exhibits corrosion resistance and durable for 150 h at industrial-grade current density in 1.0 M KOH + 0.5 M NaCl. Constructing catalytic electrodes with green economy, stability, and high efficiency is crucial for achieving overall economic water splitting. Herein, a matrix-type bismuth-modulated nickel-boron electrodes loaded on sulfurized copper foils (Bi–NiB x @CFS) is synthesized via in situ mild electroless plating. This electrode features a 2-dimensional (2D) matrix-type nanosheet structure with uniform, large pores, providing more active sites and ensuring a high gas transmission rate. Notably, the crystalline–amorphous structure constituted by the photothermal materials Bi and NiB x is loaded onto sulfide-based heterostructures. This enhances the catalytic activity through the "local photothermal effect" strategy. A performance enhancement of approximately 10 % is achieved for the Bi–NiB x @CFS at a current density of 10 mA cm−2 using this strategy at 298 K. This enhancement is equivalent to increasing the temperature of conventional electrolyte solutions by 321 K. In addition, the overpotential required to catalytically drive seawater splitting at the same current density is only 1.486 V. The Bi–NiB x @CFS electrode operates stably for 200 h without any performance degradation at industrial-grade current densities. The Bi–NiB x @CFS electrode under the "localized photothermal effect" strategy is expected to be a new type of electrocatalyst for overall seawater splitting. [ABSTRACT FROM AUTHOR]

Developing non-precious, stable, and highly efficient electrocatalyst materials is crucial for large-scale practical HER applications. Ni3S2 is a prominent catalyst due to its high efficiency and ease of preparation. Nevertheless, its usability is restricted by poor Ni site water molecule adsorption and strong hydrogen bonding between sulphur and hydrogen. The concentration of precursors and samples' morphology significantly affect the electrochemical performance of electrodes intended for the hydrogen evolution reaction (HER) application. This study examines how Mo transition metal sulfide concentration influences the Mo–Co–Ni3S2/NF catalyst's structural aspects and its subsequent electrochemical performance. In situ hydrothermal processing is used to prepare the samples through a two-step process. The samples exhibit enhanced electrocatalytic properties. Specifically, comparatively low overpotentials of 215 mV and 332 mV were observed at current densities of 10 mA cm−2 and 50 mA cm−2, respectively. Additionally, a Tafel slope of 104 mV dec−1 was recorded at a 75 : 25 ratio of molybdenum to cobalt concentration. The samples also demonstrate excellent stability. [ABSTRACT FROM AUTHOR]

Improving the electrochemical performance of electrode materials via structural design is critical in developing energy storage technologies. In this investigation, a nanoarray electrode composed of Co–Ni layered double hydroxide (Ni–Co LDH) nanosheets and Ni2SnO4 nanosheets (Ni2SnO4 NSs) stabilized on Ni foam (NF) is developed utilizing an in-situ growth method to its electrochemical properties in supercapacitors can be evaluated. The Ni2SnO4 was created in the first stage using a light hydrothermal reaction as the core. The Ni–Co LDH was then hydrothermally immobilized using the electrode, which had been made as a skeleton. The structural and textural study of the material was described using energy dispersive X-ray analysis (XRD), Fourier transforms infrared (FT–IR), field-emission scanning electron microscopy, and transmission electron microscopy. When the developed Ni–Co LDH/Ni2SnO4/NF electrode is compared to the Ni2SnO4/NF electrode, the electrochemical result shows a specific capacitance of up to 3,924 F g−1 at 1 A g−1 in a 2 mol L−1 KOH electrolyte, as well as a capacitance retention of 95% after 3000 cycles. Unsymmetrical supercapacitors made of Ni–Co LDH/Ni2SnO4/NF and activated carbon demonstrated exceptional electrochemical properties, including high rate capability, high energy, and power density (91.03 Wh kg−1 and 9.0 kW kg−1, respectively), and long cycle life. Due to its unique core/shell structural system, which facilitates ion diffusion and offers a fast electron transport kinetic model and good strain lodging, the rising pseudocapacitive behaviors render it an intriguing candidate for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

The electrocatalytic hydrogen evolution performance of FeCoNiCrMo high-entropy alloy (HEA) coating with different porosity prepared by plasma spray was investigated in this study. The feedstock powder is prepared by atomization method and mechanically mixed with an additional content of Al powder. The plasma spray prepares the mixture coatings on the Cu substrate. The porous electrocatalytic electrodes are obtained by the dealloying method. The porous HEA electrodes present the major FCC phase, the phase FeCrNiMo, and the phase Al2O3, wherein the Al2O3 formed due to the residual of the Al element. The oxides on the surface composed of Fe2O3, FeO, Co2O3, CoO, NiO, Ni2O3, Cr2O3, MoO2, and MoO3. Adding Al content increases the porosity, approaching 13.19%, 29.68%, and 47.34%. The pores are fine and dispersed in the 30 vol.% Al HEA coating, expected to present high performance. The electrochemical tests revealed that the 30 vol.% Al HEA coating presents the lowest overpotential, − 0.174 V, and the lowest charge transfer resistance, 61.91Ω, corresponding to the highest HER electrocatalytic activity. In addition, after 1000 and 2000 cycles of the CV test, the overpotential is still − 0.181 and − 0.19 V, respectively, which indicates the porous HEA coating exhibits outstanding stability. To sum up, the FeCoNiCrMo HEA system shows a potential for electrocatalyzing HER. Meanwhile, the plasma spray followed by dealloying is a feasible method to prepare the porous catalytic electrode with a high performance. This study will provide a new idea for organizing and designing catalytic electrodes. [ABSTRACT FROM AUTHOR]

The nitrogen and sulfur co‐doped graphene aerogel (SNGA) was synthesized by a one‐pot hydrothermal route using graphene oxide as the starting material and thiourea as the S and N source. The obtained SNGA with a three‐dimensionally hierarchical structure, providing more available pathways for the transport of lithium ions. The existing form of S and N was regulated by changing the calcination temperature and thiourea doping amount. The results revealed that high temperature could decompose −SOX− functional groups and promote the transformation of C−S−C to C−S, ensuring the cyclic stability of electrode materials, and increasing the thiourea dosage amount introduced more pyridine nitrogen, improving the multiplicative performance of electrode materials. Benefiting from the synergistic effect of sulfur and nitrogen atoms, the prepared SNGA showed superior rate capability (107.8 mAh g−1 at 5 A g−1), twice more than that of GA (52.8 mAh g−1), and excellent stability (232.1 mAh g−1 at 1 A g−1 after 300 cycles), 1.85 times more than that of GA (125.6 mAh g−1). The present study provides a detailed report on thiourea as a dopant to provide a sufficient basis for SNGA and a theoretical guide for further modifying. [ABSTRACT FROM AUTHOR]

Perovskite-style materials are cathode systems known for their stability in solid oxide fuel cells (SOFCs). Pr0.5Sr0.5FeO3−δ (PSF) exhibits excellent electrode performance in perovskite cathode systems at high temperatures. Via VB subgroup metals (V, Nb, and Ta) modifying the B-site, the oxidation and spin states of iron elements can be adjusted, thereby ultimately adjusting the cathode's physicochemical properties. Theoretical predictions indicate that PSF has poor stability, but the relative arrangement of the three elements on the B-site can significantly improve this material's properties. The modification of Nb has a large effect on the stability of PSF cathode materials, reaching a level of −2.746 eV. The surface structure of PSF becomes slightly more stable with an increase in the percentage of oxygen vacancy structures, but the structural instability persists. Furthermore, the differential charge density distribution and adsorption state density of the three modified cathode materials validate our adsorption energy prediction results. The initial and final states of the VB subgroup metal-doped PSF indicate that PSFN is more likely to complete the cathode surface adsorption reaction. Interestingly, XRD and EDX characterization are performed on the synthesized pure and Nb-doped PSF material, which show the orthorhombic crystal system of the composite theoretical model structure and subsequent experimental components. Although PSF exhibits strong catalytic activity, it is highly prone to decomposition and instability at high temperatures. Furthermore, PSFN, with the introduction of Nb, shows greater stability and can maintain its activity for the ORR. EIS testing clearly indicates that Nb most significantly improves the cathode. The consistency between the theoretical predictions and experimental validations indicates that Nb-doped PSF is a stable and highly active cathode electrode material with excellent catalytic activity. [ABSTRACT FROM AUTHOR]

This paper describes a Ag/AgCl electrochemical electrode for marine electric field measurements, which was prepared by depositing silver chloride on a silver foil substrate using double-pulse electrodeposition. The impact of positive direction peak current density and deposition time on electrode performance in the preparation of Ag/AgCl electrodes through double-pulse electrodeposition was investigated. Scanning electron microscopy and voltammetry have been used to study the properties of the prepared electrodes. This work reveals the correlation between the electrochemical behavior of electrodes and the physical properties of their surfaces, especially specific surface area and porosity. The study verified the characteristics of Ag/AgCl marine electric field electrodes obtained with different pulse parameters by analyzing the potential stability and noise level of the electrode in salt water. The study's results have positive significance for improving the accuracy of marine electric field measurements. [ABSTRACT FROM AUTHOR]

The mixed conducting Sr 2 Fe 1·5 Mo 0·5 O 6- δ (SFM) is a promising cobalt-free oxygen electrode for solid oxide fuel cells (SOFCs). Therefore, we report on modifying the electrode microstructure of a single-phase SFM and the formation of a new composite electrode with ∼34 vol% of Ce 0.8 Pr 0.2 O 2- δ (CPO, which also exhibits mixed conducting behavior). In our assessment, we tested the impact of repeated drying-screen-printing cycles on the deposition of the electrode films. Such a modification resulted in an optimal thickness within the 40–50 μm range while providing a higher solid fraction within the electrode-electrolyte region. This factor decreased the total polarization resistance for both electrode materials, as determined by electrochemical impedance spectroscopy. The results also indicated enhanced surface exchange kinetics with the addition of CPO, where the incorporation reaction is expected to occur at the SFM/CPO interface. Nevertheless, the overall performance of the composite electrode was hampered by an insufficient global electronic conductivity. As a result, the reduced effective electroactive area in the SFM/CPO composite electrode hindered the interfacial charge-transfer process. Our work provides an important investigation of both microstructural and compositional criteria for the future development of SOFC cathode design. • The effect of layer deposition on the R pol of SFM electrodes was examined. • The SFM/CPO composite was first evaluated as an oxygen electrode for SOCs. • The Gerischer element suggested improved oxygen reaction kinetics with CPO. • The reduced effective area impaired interfacial charge transfer in the composite. • The addition of CPO (∼34 vol%) increased the R pol of SFM electrodes due to its lower electronic conductivity. [ABSTRACT FROM AUTHOR]

Low‐cost and high‐loading cathodes are crucial for practical application of zinc‐ion supercapacitors (ZICs) but achieving optimal performance in high‐loading electrodes faces challenges due to sluggish ion transport, increased resistance, and unstable structure. Guided by theoretical calculations, high‐loading carbon cathodes based on holey activated carbon sheets (HACS) are fabricated from a carefully chosen molecule. A simple pyrolysis‐leaching treatment transformed the molecule into HACS with large surface area, hierarchical porous structure, and electroactive oxygen/nitrogen dopants. When combined with an aqueous binder, the optimized HACS‐based high‐loading electrode (16.1 mg cm−2) exhibits high‐capacitance (454 F g−1) and fast‐rate (1 A g−1) characteristics under lean electrolyte (6.2 µL mg−1). More impressively, HACS is dry‐pressed into free‐standing thick electrodes up to 35.4 mg cm−2 and corresponding practical ZIC under limited Zn and low N/P ratio demonstrates ultrahigh areal capacitance (9 F cm−2) and energy density (3.47 mWh cm−2). The outstanding performance can be attributed to fast ion transport enabled by through‐plane pores of HACS, as well as abundant double‐layer and redox‐active surfaces from favorable heteroatom‐doped porous nanosheets. With its cost‐effectiveness, elemental abundance, and structural tunability, this molecular carbon strategy offers a platform for making self‐activated carbon electrodes at the molecular level towards practical supercapacitors. [ABSTRACT FROM AUTHOR]

Cu-doped TiO2 film electrodes are synthesized via sol–gel technique and physically characterized. The Cu-doped TiO2 film electrodes is sensitized by tetrakis (4-carboxyphenyl) porphyrin and applied as a photoanode of a photoelectrochemical biofuel cell (PEBFC). The Cu/TiO2-based PEBFCs show a short-circuit current (Isc) of 75.9 μA, an open-circuit potential (Voc) of 912 mV, a maximum power density (Pmax) of 66.43 μW/cm2 and an overall energy conversion efficiency (η) of 2.16%, respectively. The PEBFCs indicate improved photoelectric performances comparing the TiO2-based PEBFC (Isc: 72.5 μA, Voc: 740 mV, Pmax: 35.34 μW/cm2, η: 1.52%). The Cu/TiO2-based PEBFCs also indicate a higher incident photon-to-collected electron conversion efficiency (IPCE), which is probably due that the doped copper reduces the band gap of a wide-gap TiO2 semiconductor as shown by ab initio band calculation. And the Cu/TiO2-based PEBFC can provide long electron lifetime and decrease electron–hole pair recombination rate, which is responsible for the better performance in the Cu/TiO2-based PEBFC than in the TiO2-based PEBFC. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) can be transformed from alkaline supercapacitor material into metal-cation storage cathode working in neutral electrolytes through electrochemical activation. However, the rate performance for storing large cations is restricted by the small interlayer distance of LDH. Herein, the interlayer distance of NiCo-LDH is expanded by replacing the interlayer nitrate ions with 1,4-benzenedicarboxylic anions (BDC), leading to the enhanced rate performance for storing large cations (Na+, Mg2+, and Zn2+), whereas almost the unchanged one for storing small-radius Li+ ions. The improved rate performance of the BDC-pillared LDH (LDH-BDC) stems from the reduced charge-transfer and Warburg resistances during charge/discharge due to the increased interlayer distance, as revealed by in situ electrochemical impedance spectra. The asymmetric zinc-ion supercapacitor assembled with LDH-BDC and activated carbon presents high energy density and cycling stability. This study demonstrates an effective strategy to improve the large cation storage performance of LDH electrodes by increasing the interlayer distance. [ABSTRACT FROM AUTHOR]

[Display omitted] Regarding carbon-based electrodes, simultaneously establishing a well-defined meso -porous architecture, introducing abundant hetero-atoms and improving the graphitization degree can effectively enhance their capacitive performance. However, it remains a significant challenge to achieve a good balance between defects and graphitization degree. In this study, the porous structure and composition of carbon materials are co-optimised through a 'dual-function' strategy. Briefly, K 3 Fe(C 2 O 4) 3 and H 3 BO 3 were hybridised with a gelatin aqueous solution to form a homogeneous composite hydrogel, followed by lyophilisation and carbonisation. Owing to the dual functionality of raw materials, the graphitization, activation and hetero-atom doping processes can occur simultaneously during a one-step high-temperature treatment. The resultant carbon material exhibits a high graphitization degree (I D /I G = 0.9 ± 0.1), high hetero-atom content (N: 9.0 ± 0.3 at.%, B: 6.9 ± 0.5 at.%) and a large specific area (1754 ± 58 m2/g). The as-prepared electrode demonstrates a superior capacitance of 383 ± 1F g−1 at 1 A/g. Interestingly, the cyclic voltammetry (CV) curves exhibit a distinctive pair of broad redox peaks, which is uncommon in KOH electrolyte. Experiment data and density functional theory (DFT) simulation verify that N-5, B co-doping enhances the activity of the faradic reaction of carbon electrodes in KOH electrolyte. Furthermore, the fabricated Zn-ion hybrid supercapacitor (ZHSC) based on this carbon electrode delivers a high-energy density of 140.7 W h kg−1 at a power density of 840 W kg−1. [ABSTRACT FROM AUTHOR]

[Display omitted] Binary metal phosphate electrodes have been widely studied for energy storage applications due to the synergistic effects of two different transition elements that able to provide better conductivity and stability. Herein, the battery-type binder-free nickel-manganese phosphate (NiMn-phosphate) electrodes were fabricated with different Ni:Mn precursor ratios via microwave-assisted hydrothermal technique for 5 min at 90 °C. Overall, NiMn3P electrode (Ni:Mn = 1:3) showed an outstanding electrochemical performance, displaying the highest specific (areal) capacity at 3 A/g of 1262.4 C/g (0.44 C/cm2), and the smallest charge transfer resistance of 108.8 Ω. The enhanced performance of NiMn3P electrode can be ascribed to the fully grown amorphous nature and small-sized flake and flower structures of NiMn3P electrode material on the nickel foam (NF) surface. This configuration offered a higher number of active sites and a larger exposed area, facilitating efficient electrochemical reactions with the electrolyte. Consequently, the NiMn3P//AC electrode combination was chosen to further investigate its performance in supercapattery. The NiMn3P//AC supercapattery exhibited remarkable energy density of 105.4 Wh/kg and excellent cyclic stability with 84.7% retention after 3000 cycles. These findings underscored the superior electrochemical performance of the battery-type binder-free NiMn3P electrode, and highlight its potential for enhancing the overall performance of supercapattery. [ABSTRACT FROM AUTHOR]

The nickel metal nanoparticles and 3D nitrogen-doped carbon matrix are adopted to embellish nickel oxide via a simplified hard template method. This strategy will shine the route to prepare and ameliorate the electrochemical performance of NiO-based electrodes and other-type electrodes for energy storage. [Display omitted] Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO–Ni/N–C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO–Ni/N–C electrode leads it to exhibit a capacity of 1310.8 mAh g-1 at 0.1 A g-1 for 120 loops and a rate capability of 441.5 mAh g-1 at 20.0 A g-1. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications. [ABSTRACT FROM AUTHOR]

Developing advanced electrode materials for supercapacitors (SCs) has received incredible attention. The suitable electrode for high capacitance and energy density are significant challenges for SCs. This work reports an efficient hydrothermal synthesis of MoS2 nanosheets on carbon cloth (MoS2@CC). The large surface area of the binder-free MoS2@CC electrode provides rich active sites and an improved electrolyte ion diffusion rate. The MoS2@CC electrode exhibits good electrochemical performance by delivering a high specific capacitance of 947 F g−1 at the current density of 1.0 A g−1 and retains an excellent capacitance of 96.5% over 10 000 cycles. The high performance of the MoS2@CC electrode can be clarified through density functional theory (DFT) calculations. The DFT outcomes reveal that the electrode possesses favorable Li-ion intercalation and adsorption properties. The calculated adsorption energy of −0.352 eV at the hollow site shows the high stability of the system. The low energy barrier of path 1 (0.83 eV) easily facilitates Li-ions in the electrode material, which is beneficial for its fast electrochemical performance. The obtained results of the MoS2@CC electrode present improved pseudocapacitive performance, showing a significant possibility for high-performance SCs' application. [ABSTRACT FROM AUTHOR]

An organic bipolar polymer electrode called poly[anthraquinone‐alt‐dihydrophenazine] (PAD) is in situ synthesized between the two‐electron n‐type unit of dibromoanthraquinone and two‐electron p‐type unit of dihydrophenazine on the layered MXene nanosheets, leading to the formation of the material composition called PAD@MX. PAD@MX shows almost the same redox mechanism and electrode performance in Na/K‐based batteries. In Na/K‐based half cells, PAD@MX can show the peak discharge capacities of 240/255 mAh g−1 and peak energy densities of 511/597 Wh kg−1, respectively, which are among the top results for cathodes in the world. Furthermore, the Na/K‐based dual‐ion symmetric batteries can be simultaneously constructed by using PAD@MX as the single electrode material. Both symmetric batteries fulfill the "ready‐to‐charge" property without any pre‐activation. Therein, PAD@MX delivers the reversible discharge capacities of 86/104 mAh g−1cathode and energy densities of 54/64 Wh kg−1total mass, stably running for 500 cycles. To the best of our knowledge, this is the first example of organic bipolar electrodes simultaneously applied to the Na/K‐based dual‐ion symmetric batteries in the world. [ABSTRACT FROM AUTHOR]

The impact of varying electrolytic solutions on the electrochemical performance of electrode substances is significant. Consequently, this research investigates the effects of different electrolytes on the performance of nickel pyrophosphate (Ni 2 P 2 O 7) electrodes in the context of supercapacitor applications. Nickel pyrophosphate electrodes were synthesized on nickel foam (NF) substrates using a facile, scalable chemical bath deposition (CBD) technique. The Ni 2 P 2 O 7 material characterized different physico-chemical comprehensive characterization. Electrochemical assessments of Ni 2 P 2 O 7 /NF electrode were conducted in 2 M solutions of KOH, NaOH, and LiOH. Notably, in a 2 M KOH milieu, Ni 2 P 2 O 7 exhibited a superior specific capacity of 156.3 mAh/g at 50 mA/cm2, alongside a cyclic retention rate of 71.6% after 5000th CV cycles. Additionally, it demonstrated enhanced energy (31.26 Wh/kg) and power densities (699 W/kg). Moreover, a Ni 2 P 2 O 7 /NF-based symmetrical solid-state energy storage device revealed a specific capacitance of 163.53 F/g, with energy and power densities of 7.25 Wh/kg and 125 W/kg, respectively, at a current density of 2 mA/cm2. This study highlighted the need to choose an appropriate electrolyte based on the electrode material. [Display omitted] • Monoclinic NPO/NF microstructure prepared by cost effective chemical bath deposition method. • NPO/NF micro-plates are well-separated for better penetration of alkaline electrolytes. • The influence of different alkaline electrolytes on the electrochemical properties of optimized NPO/NF is examined. • The synergetic effect between microplates and the electrolytes boosted the overall performance of NPO/NF. • Fabricated and evaluated the performance of a symmetric device which shows excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are porous materials assembled using metal and organic linkers, showing a high specific surface area and a tunable pore size. Large portions of metal open sites in MOFs can be exposed to electrolyte ions, meaning they have high potential to be used as electrode materials in energy storage devices such as supercapacitors. Also, they can be easily converted into porous metal oxides by heat treatment. In this study, we obtained high energy storage performance by preparing electrode materials through applying heat treatment to manganese MOFs (Mn-MOFs) under air. The chemical and structural properties of synthesized and thermally treated Mn-MOFs were measured by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The surface area and porosity were investigated by nitrogen adsorption/desorption isotherms. The electrochemical properties were studied by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) using a three-electrode cell. It was found that Mn-MOF electrodes that underwent heat treatment at 400 °C under air consisted of Mn2O3 with high specific surface area and porosity. They also showed a superior specific capacitance of 214.0 F g−1 and an energy density value of 29.7 Wh kg−1 (at 0.1 A g−1) compared to non-treated Mn-MOFs. [ABSTRACT FROM AUTHOR]

Lithium-sulphur (Li-S) batteries offer high energy density compared to lithium-ion batteries, emerging as a promising technology for the next generation of energy storage systems. The ongoing challenge is to improve their electrochemical performance, extend their useful life and mitigate some problems that persist in this technology, by the investigation in materials with diverse properties. This work seeks to elucidate the importance and repercussions associated with functionalisation of graphene-based materials through nitrogen incorporation (more than 9 wt.% N), employing different chemical agents such as ethylenediamine and ammonia. Herein, differences in both the textural properties and the chemical environment of nitrogen within the carbonaceous network are identified, resulting in distinct electrochemical behaviours. The electrochemical performance of electrodes prepared from ammonia-functionalised samples surpasses that of ethylenediamine-functionalised samples in terms of both efficiency and rate performance. Conversely, the ethylenediamine-functionalised samples excel in stability, showing exceptional values in capacity retention per cycle. The outcomes exceeded expectations in energy performance, allowing the Li-S cells to be subjected to ultra-high rate cycling while maintaining appropriate capacity values. [ABSTRACT FROM AUTHOR]

The preparation of composite carbon nanomaterials is one of the methods for improving the electrochemical performance of carbon-based electrode materials for supercapacitors. However, traditional preparation methods are complicated and time-consuming, and the binder also leads to an increase in impedance and a decrease in specific capacitance. Therefore, in this work, we reduced Ni-Cu nanoparticles on the surface of nitrogen-doped carbon nanofibers (CNFs) by employing an electrostatic spinning method combined with pre-oxidation and annealing treatments. At the same time, Ni-Cu nanoparticles were vulcanized to Ni–Cu–S nanoparticles without destroying the structure of the CNFs. The area-specific capacitance of the CNFs/Ni–Cu–S–300 electrode reaches 1208 mF cm−2 at a current density of 1 mA cm−2, and the electrode has a good cycling stability with a capacitance retention rate of 76.5% after 5000 cycles. As a self-supporting electrode, this electrode can avoid the problem of the poor adhesion of electrode materials and the low utilization of active materials due to the inactivity of the binder and conductive agent in conventional collector electrodes, so it has excellent potential for application. [ABSTRACT FROM AUTHOR]

Novel two‐layer nanostructured electrodes are successfully prepared for their application in membrane capacitive deionization (MCDI) processes. Nanostructured carbonaceous materials such as graphene oxide (GO) and carbon nanotubes (CNTs), as well as activated carbon (AC) are dispersed in a solution of poly(vinyl alcohol) (PVA), mixed with polyacrylic acid (PAA) or polydimethyldiallylammonium chloride (PDMDAAC), and subsequently cast on the top surface of an AC‐based modified graphite electrode to form a thin composite layer that is cross‐linked with glutaraldehyde (GA). Cyclic voltammetry (CV) is performed to investigate the electrochemical properties of the composite electrodes and desalination experiments are conducted in batch mode using a MCDI unit cell to investigate the effects of i) the nanostructured carbonaceous material, ii) its concentration in the polymer blend, and iii) the molecular weight of the polymers on the desalination efficiency of the system. Comparative studies with commercial membranes are performed proving that the composite nanostructured electrodes are more efficient in salt removal. The improved performance of the composite electrodes is attributed to the ion exchange properties of the selected polymers and the increased specific capacitance of the nanostructured carbonaceous materials. This research paves the way for wider application of MCDI in water desalination. [ABSTRACT FROM AUTHOR]

In this work, nickel-catecholate (Ni-CAT) nanorods were in situ compounded on graphene oxide (GO) to form a composite Ni-CAT@GO (NCG) with a special "blanket-shape" structure, which was used as an electrode material for supercapacitors. The morphology of Ni-CATs in situ grown on GO was modulated by introducing various contents of GO. With increasing GO, the length of nanorods of Ni-CATs is obviously shortened, and the charge transfer resistance of NCG is significantly reduced as the GO content is relatively low while it increases with further addition of GO, because excessive GO in NCG results in smaller crystal sizes accompanied by smaller stacking pores. Both the over-long Ni-CAT nanorods and the smaller stacking pores can restrict the accessible surface areas for the electrolyte. Optimal nanorod sizes are crucial to achieve good electrochemical performance for electrode materials. Galvanostatic charge–discharge analysis of NCG electrodes shows that their capacity initially increases and then decreases with the addition of more and more GO, and Ni-CAT@GO-0.5 (NCG0.5) with minimal charge transfer resistance exhibits the best electrochemical performance. The results demonstrate that the NCG0.5 electrode with optimal morphology possesses an excellent capacitance of 563.8 F g−1 at 0.5 A g−1 and a good rate performance of 61.9% at 10 A g−1, indicating that Ni-CAT@GO is a new type of promising electrode material for supercapacitors based on conductive metal–organic frameworks. [ABSTRACT FROM AUTHOR]