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The capacitive deionization technology uses the electrochemical adsorption of ions in porous electrodes to desalinate seawater or brackish water. Recently, capacitive deionization has gained significant attention as a technology for selective adsorption of ionic species from multicomponent aqueous electrolytes. To investigate the mechanism of selective adsorption at the molecular level, we performed molecular dynamics simulations of aqueous electrolytes and porous electrodes with different divalent or trivalent ions, electrode pore sizes, and applied voltages. We calculated the free energy barriers preventing ions from entering the pores of the electrode and the structure of the water molecules near the ions and the electrode surface under various conditions. Our results suggest that, when the pore and ion sizes are comparable, the steric and electrostatic interactions between the hydrated ions and electrode pores are comparable in magnitude. Moreover, the relative importance of the two interactions can be reversed by slight changes in the external conditions, such as the ion size, valence of the ions, electrode pore size, and applied voltage. Thus, by finely tuning the electrode pore size and the applied voltage, it may be possible to selectively adsorb a particular ionic species from a multicomponent electrolyte through capacitive deionization using a porous electrode. [ABSTRACT FROM AUTHOR]

We investigate the formation and transport of gas bubbles across a model porous electrode/catalyst using lattice Boltzmann simulations. This approach enables us to systematically examine the influence of a wide range of morphologies, flow velocities, and reaction rates on the efficiency of gas production. By exploring these parameters, we identify critical parameter combinations that significantly contribute to an enhanced yield of gas output. Our simulations reveal the existence of an optimal pore geometry for which the product output is maximized. Intriguingly, we also observe that lower flow velocities improve gas production by leveraging coalescence-induced bubble detachment from the electrode/catalyst. [ABSTRACT FROM AUTHOR]

This study proposes the synthesis of SnO 2 /Ti 3 C 2 T x composites on porous graphene electrodes (PGEs) for high-performance humidity sensors. In the heterojunction structure of SnO 2 /Ti 3 C 2 T x composites, SnO 2 nanoparticles prevented the layered structure of Ti 3 C 2 T x to collapse and restack. Moreover, the high specific surface area of the SnO 2 /Ti 3 C 2 T x composites provided more adsorption sites that improved their response. Porous graphene was fabricated by a fiber laser-induced process on the polyimide film as an electrode layer for flexible humidity sensors. The characteristics of the SnO 2 /Ti 3 C 2 T x composites and PGEs were examined and investigated. SnO 2 /Ti 3 C 2 T x composites were drop-cast on PGEs to fabricate the humidity sensor. Furthermore, the response of humidity sensors was tested in various RHs. The performance of the proposed humidity sensor demonstrated a wide detection range of 11–97 % RH, low hysteresis of 2.8 % RH, low response/recovery times of 14/49 s, high sensitivity of 862.19 kΩ/%RH, excellent long-time stability and repeatability, and good flexibility. In the future, the proposed sensor can be widely applied in human respiration monitoring, non-contact switch, and detection of volatile organic compounds. [ABSTRACT FROM AUTHOR]

Activated carbon derived from biomass offers several advantages, including high surface area, customizable pore sizes, abundance, resilience across temperatures, and cost-effectiveness. This study focuses on exploring the potential of palm shell as a renewable alternative for supercapacitor electrode materials. Specifically, it investigates the utilization of a gel composed of NaOH and PVA for activating carbon. Here, palm shell undergoes chemical activation, and its resulting activated carbon's structural and physicochemical properties are comprehensively examined using XRD, FTIR, and BET measurements. The investigation delves into the electrochemical properties using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy of electrodes fabricated from chemically activated carbon derived from palm shells. The activated carbon enhanced a surface area of 216.062 m2 g−1 and a pore volume of 0.1468 cm3 g−1, and it is produced through the innovative approach of gel-based activation. This research highlights the potential of palm shell-derived activated carbon as a viable, sustainable, and efficient material for supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

This study examines the use of surface-modified biochar as a porous electrode material for the capacitive deionization removal of chloride and fluoride ions. Incorporation of titanium dioxide and amine groups on biochar aims to increase surface-active sites, facilitate salt ion diffusion, and improve charge efficiency and cation/anion selectivity in asymmetric capacitive deionization. Titania, amine, and activated biochar are denoted as TB, AmB, and AcB, respectively. Physical and electrochemical characterizations were performed to investigate the surface properties of fabricated materials. At the optimum TiO2 loading of 5% (TB-05), the specific capacitance of TB-05 electrode was improved by 35% at scan rate of 1 mV s–1 in comparison to the AcB electrode, despite a decrease in the specific surface area. Three different asymmetric capacitive deionization cell designs—AmB||TB-05, AcB||TB-05, and AmB||AcB—and two symmetrical cell designs—AcB||AcB and TB-05||TB-05 (anode||cathode)—were tested. A symmetric cell design TB-05||TB-05 had a NaCl removal capacity of 8.51 mg g−1, a 42% improvement in comparison to a symmetric AcB cell (6.01 mg g−1). Further, an asymmetric cell AmB||TB-05 showed 67% charge efficiency improvement over symmetric AcB cell, likely due to a reduced co-ion effect. For fluoride removal, a symmetric TB-05 cell showed a removal capacity of 3.51 mg g−1. This study promotes simple surface-modification methods to make inexpensive commercial biochar into a sustainable, and efficient electrode material available for a scale-up asymmetric capacitive deionization. [ABSTRACT FROM AUTHOR]

Commercialization of solid oxide fuel cell (SOFC) is restricted due to long term performance degradation. SOFC is activated by diffusion of gasses through porous electrodes to the electrochemical active sites termed as triple phase boundary (TPB). Among all other parameters, tortuosity influences the functionality of TPB and is responsible for gas transport which relates its bulk diffusion and its migration through the porous electrode. The novelty of present research lies in designing of optimum tortuous gas diffusion path for effective hydrogen oxidation reaction through engineered morphology of anode functional layer. The study involves the fabrication of anode for planar SOFC using four configurations. Configuration A and B involves anode monolith synthesized through conventional route [(40 vol % Ni in dispersed-8 mol % Yttria stabilized zirconia (SZ)] and functional core-shell Ni@SZ. Configuration C (trilayer anode, TLA) is designed to have graded matrix with conventional Ni-SZ (fuel inlet side), 28 vol% Ni@SZ acting as active layer and 32 vol % Ni@SZ sandwiched in between. Configuration D consists of Ni@SZ as the active layer onto conventional Ni-SZ support. TLA is found to have minimum tortuosity (τ = 2) with maximum cell endurance for 2000 h (2.06–8.2 %/1000 h@800 °C under load). Ni@SZ with unimodal pore distribution is capable of reducing the activation barrier for charge migration (14 kJmol-1) compared to Ni-SZ (32 kJmol-1) with multimodal pores. This results in higher redox tolerance for Configuration B-D (4–7 % conductivity degradation/20 cycles) compared to Configuration A (27% conductivity degradation/20 cycles). Post mortem analyses of microstructure support the retention of core-shell morphology of Ni@SZ with lower deterioration. [Display omitted] • Optimization of electrochemical anodic reaction through unique microstructure of Ni-YSZ. • Tortuosity is established as the primary descriptor to control fuel TPB. • Tri-layer Ni-YSZ shows minimum tortuosity (τ=2), degradation (39 mΩ-cm2kh−1@0.5 A.cm−2,800 C. • TLA composed of conventional anode as support & Ni@SZ (electrochemical active layer). • HOR established as non-equilibrium till propagation & diffuses to equilibrium (saturation). [ABSTRACT FROM AUTHOR]

The direct electrolysis of seawater for the production of green hydrogen energy is an economically attractive approach. However, this technique confronts technical problems because to the oxygen evolution reaction (OER) weak stability and inadequate selectivity due to competition with the chlorine evolution process. This work focuses on improving the stability of the electrode and electrolysis efficiency. The phosphating NiCoP active layer with 3D porous morphology was created by electrodeposition on the B-doped diamond (BDD) as an electrode inspired by the bifunctional catalysis strategy. The successfully constructed unique cube-on-nanosheets structure in the NiCoP active layer enables the electrode to exhibit excellent electrocatalytic performance. The porous NiCoP/BDD (Por-NiCoP/BDD) electrodes showed good catalytic activity in alkaline-simulated seawater with the OER and hydrogen evolution reaction (HER) overpotentials of 400 and 261 mV, respectively, at a current density of 100 mA cm−2. More importantly, the electrode exhibits interesting stability of the catalytic performance and structural in alkaline-simulated seawater electrolysis, with the current density decaying by only 1.52 % and 4.06 % after OER and HER processes for 50 h, respectively. This work expands the valuable application scenarios of BDD electrode and provides novel ideas for the development of seawater electrolysis. [Display omitted] • The controllable preparation of Por-NiCoP/BDD electrodes with 3D porous morphology was achieved. • The constructed NiCoP catalytic layer presents an interesting cauliflower-like structure. • The Por-NiCoP/BDD electrodes exhibit interesting bifunctional catalytic performance (OER and HER). • The Por-NiCoP/BDD electrodes exhibited attractive structural stability in alkaline-simulated seawater. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSBs) with adequately selected cathode materials exhibit a higher energy density and better safety than conventional lithium-ion batteries (LIBs). Ni-rich layered cathodes are benchmark materials for traditional LIBs owing to their high energy density. Recent studies have highlighted the advantages of using crack-free, single-crystalline cathode materials in ASSBs. In this study, a scalable infiltration sheet-type process was used to fabricate composite electrodes with different cathode-material morphologies for ASSBs. Typically, crack-free single-crystalline materials exhibit better retention performance and lower rate capability (i.e., slower kinetics in charge‒discharge processes) than polycrystalline cathode materials. Li6PS5Cl-infiltrated polycrystalline electrodes showed excellent retention performance and rate capability. Galvanostatic intermittent titration technique analysis and transmission electron microscopy of the single-crystalline electrode confirmed severe polarization and the presence of a rock-salt-structure layer in the cathode particles; these results indicated side reactions within the layered structure of the material. In contrast, composite electrodes consisting of polycrystalline cathode materials infiltrated with the solid electrolyte Li6PS5Cl showed excellent electrochemical performance owing to intimate electrode–electrolyte interfacial contact. The result from this study confirmed the critical influence of interface engineering and material morphology on the overall performance and stability of ASSBs and could facilitate the development of high-performance ASSBs in the future. This study introduces a technique for utilizing conventional lithium-ion battery electrodes in all-solid-state batteries. By infiltrating a solid electrolyte solution into the porous electrode, the effects based on the morphology of the active material were investigated. In poly-crystalline materials, high coverage and the formation of a thin side reaction layer were observed. Consequently, the infiltration process also confirmed the superior performance of poly-crystalline materials. [ABSTRACT FROM AUTHOR]

The current goals for implementing the hydrogen economy have highlighted a need to further optimize water‐splitting technologies for clean hydrogen production. Proton exchange membrane water electrolysis (PEMWE) is a leading technology, but further optimizations of anode materials including the porous transport layer (PTL) and the adjacent catalyst layer (CL) are required to increase overall cell performance and reduce cost. This literature review describes advances in PTL development and characterization, highlighting early PTL characterization work and most common methods including capillary flow porometry and mercury intrusion porometry, optical imaging, neutron and x‐ray radiography, and x‐ray computed tomography. The article also discusses PTL protective coatings and their characterizations, focusing on platinum group metal (PGM)‐based coatings, alternative non‐PGM‐based coatings, post‐treated PTLs, and investigations into thin PGM‐based coatings. Furthermore, it highlights the integration of the PTL and the adjacent CL along with associated characterization challenges. Lastly, this review discusses future developments in the characterization needed to improve PEMWE's performance and long‐term durability are discussed. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS), characterized by its non‐destructive and in situ nature, plays a crucial role in comprehending the thermodynamic and kinetic processes occurring within Li‐ion batteries. However, there is a lack of consistent and coherent physical interpretations for the EIS of porous electrodes. Therefore, it is imperative to conduct thorough investigations into the underlying physical mechanisms of EIS. Herein, by employing reference electrode in batteries, we revisit the associated physical interpretation of EIS at different frequencies. Combining different battery configurations, temperature‐dependent experiments, and elaborated distribution of relaxation time analysis, we find that the ion transport in porous electrode channels and pseudo‐capacitance behavior dominate the high‐frequency and mid‐frequency impedance arcs, respectively. This work offers a perspective for the physical interpretation of EIS and also sheds light on the understanding of EIS characteristics in other advanced energy storage systems. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach through the design and creation of a composite electrode, uniquely made of three distinct layers of micro/mesoporous electrospun carbon nanofiber (CNF) mats, featuring a gradient in pore size. This innovative gradient pore structure merges the benefits of varying pore sizes, significantly enhancing redox flow battery (RFB) efficiency. The first layer, a microporous CNF mat situated near the membrane, offers an extensive reactive surface area, minimizing charge transfer resistance and speeding up electrochemical reactions—key factors in enhancing battery reaction efficiency. The next layer, a mesoporous CNF mat, fine‐tunes the flow properties of the electrolyte, lowering flow resistance while ensuring superior charge transfer capabilities. This structured gradient in pore size not only facilitates improved electrolyte penetration and even distribution but also harmonizes the balance between charge transfer efficiency and electrolyte flow, thus mitigating energy losses without compromising reaction velocity. Charge–discharge testing demonstrated notable performance gains: an energy efficiency of 82% at 100 mA cm−2 (surpassing traditional electrodes by 71.5%) and 69% at 200 mA cm−2, alongside a 77.4% increase in peak power density. This advancement not only enhances energy and power densities but also its lifespan, marking a significant step forward for RFB technologies. [ABSTRACT FROM AUTHOR]

In electrochemical discharge machining (ECDM), continuous renewal of electrolyte between the tool electrode and the workpiece guarantees stable discharge machining. Proposed in this paper is Porous-electrode ECDM (p-ECDM) using a tool electrode made of porous material containing micrometer pores. The rough surface of the porous electrode promotes electrolyte regeneration between the electrodes to produce a stable and relatively thin gas film. At the same time, the internal connected micropores are used to provide controlled gas flow to the processing area, reduce the energy consumption of electrolytic bubbles, and improve the discharge energy to achieve efficient ECDM processing. Experimental results indicate that compared with a solid electrode, the porous electrode has faster electrolyte renewal, smaller bubble volume, more-stable voltage characteristics, 22.55% less overcut, a 4.7% smaller heat-affected zone, and better deep hole processing ability. Experimental results for p-ECDM assisted by controlled airflow demonstrate a 54.23% increase in the material removal rate. [ABSTRACT FROM AUTHOR]

Recent advances in 3D printing have enabled the manufacture of porous electrodes which cannot be machined using traditional methods. With micron-scale precision, the pore structure of an electrode can now be designed for optimal energy efficiency, and a 3D printed electrode is not limited to a single uniform porosity. As these electrodes scale in size, however, the total number of possible pore designs can be intractable; choosing an appropriate pore distribution manually can be a complex task. To address this challenge, we adopt an inverse design approach. Using physics-based models, the electrode structure is optimized to minimize power losses in a flow reactor. The computer-generated structure is then printed and benchmarked against homogeneous porosity electrodes. We show how an optimized electrode decreases the power requirements by 16% compared to the best-case homogeneous porosity. Future work could apply this approach to flow batteries, electrolyzers, and fuel cells to accelerate their design and implementation. [ABSTRACT FROM AUTHOR]

Highlights Structural battery composites (SBCs) represent an emerging multifunctional technology in which materials functionalized with energy storage capabilities are used to build load‐bearing structural components. However, due to the liquid electrolyte contamination in structural battery electrolyte (SBE) and the large volume expansion of active battery materials, the poor interlayer interfacial in multilayer SBCs often causes difficulties in practical use. In this study, a new porous LiFePO4‐graphite SBC is designed and fabricated by independently distributing battery materials and resin matrix on carbon fiber fabric in pattern lattice form to prepare electrodes prepreg. The cured porous composite framework supports the load‐bearing function while limiting the electrochemical reaction in liquid electrolyte within lattices. The electrodes show reversible electric resistance after 3000 bending cycles with radius as small as 10 mm. The mechanical properties enhance significantly with tensile strength of 486.1 MPa and Young's modulus of 9.1 GPa compared to that with a liquid–solid biphasic mixed SBE structure. The SBC also exhibits a favorable capacity of 27.8 mAh/g at 0.1C. This straightforward integration path of mechanical and electrical functionalities is compatible with the manufacturing process of aerospace composite structures, which will provide an efficient and convenient energy supply solution for distributed electronics. A porous full‐cell structural battery composite (SBC) was designed and fabricated with prepregs. A suspension deposition and volatilization method was developed for robust battery material coating. Electrodes layer exhibited reversible electric resistance after 3000 tensile/bending cycles. The tensile strength and modulus increased significantly compared to the SBC with liquid–solid biphasic mixed structural battery electrolyte. Coordinated integration path was completely compatible with the manufacturing process of aerospace composite structures. [ABSTRACT FROM AUTHOR]

An electrical double‐layer capacitor (EDLC) comprises two porous electrodes sandwiching an electrolyte‐permeable separator, which prevents the electrodes from short‐circuiting. While previous studies have mainly focused on electrolyte and electrode properties of EDLCs, the device configuration in terms of electrode and separator sizes received less attention, with separators often simplistically modelled as infinitely large reservoirs of ions. Herein, we investigate how the relationship between electrode and separator thicknesses impacts EDLC charging. We find that the assumption of bulk reservoir holds only under specific conditions. Moreover, we identify a tradeoff between stored energy density and pressure variations within the separator, potentially jeopardizing the EDLC durability. We also explore the influence of ionic liquid additives on EDLC charging. While prior research has shown that trace amounts of uncharged additives with strong electrode affinity can significantly enhance energy storage, we observe this effect as negligible for electrodes and separators of comparable sizes. Instead, we show how to optimize EDLC performance by fine‐tuning the concentration of additives and separator‐to‐electrode size ratio to maximize stored energy density. [ABSTRACT FROM AUTHOR]

Nickel/oxygen ion conducting ceramic composite powders (Ni/YSZ) are commonly used materials for fuel electrodes of solid oxide fuel cells and electrolyzers. One of the ways for increasing the activity of Ni/YSZ is infiltration/impregnation, where a formed porous electrode is impregnated with solutions of active elements, followed by thermolysis. In this study, Ni/YSZ electrodes simultaneously impregnated with nickel and ceria particles in different ratios are investigated. It is shown that the introduction of highly dispersed nickel only slightly increases the activity of the Ni/YSZ electrode and does not affect the pathway of the hydrogen oxidation reaction. If a minor amount of ceria particles is introduced into the electrode, it significantly increases its activity and partially changes the reaction mechanism. The best performance is obtained for the electrode impregnated with an equal volume solution of nickel and cerium nitrates. The polarization resistance of such an electrode in wet hydrogen is about 0.05 and 0.17 Ohm cm2 at 850 and 600 °C, respectively, which is about 10 and 65 times lower compared to initial Ni/YSZ. Long-term tests of more than 1100 h in a wet hydrogen atmosphere at 700 °C showed satisfactory stability of polarization resistance of all investigated electrodes. [Display omitted] • Ni/YSZ electrodes infiltrated with nickel and/or ceria were investigated. • The injection of nickel resulted in a negligible enhancement of Ni/YSZ activity. • Introduction of minor amounts of ceria leads to a partial change in HOR mechanism. • Introduction of close amounts of nickel and cerium is most effective. • Introduction of a significant amount of ceria completely changes the HOR mechanism. [ABSTRACT FROM AUTHOR]

In polymer membrane fuel cells (PEMFC), the pore microstructure and the effective diffusion coefficient ( D eff ) of the catalytic layer have a significant impact on the overall performance of the fuel cell. In this work, numerical methods to simulate PEMFC catalytic layers were used to study the effect of isotropy ( I xy ) on the D eff . The proposed methodology studies reconstructed systems by Simulated Annealing imaging with different surface fractions of microstructures composed by two diffusive phases: agglomerates and pores. The D eff is determined numerically by the Finite Volume Method solved for Fick's First Law of Diffusion. The results show that the proposed methodology can effectively quantify the effect of isotropy on the D eff for both diffusion phases. Two trends were obtained in the magnitude of the D eff concerning the change in isotropy: (1) an analytical equation is proposed in this article for D eff ≥ 5 % D 0 and (2) numerical solutions are determined for D eff < 5 % D 0. In our analytical equation are both a lineal and a logarithmic sweep. When the surface fraction is ∅ = 50%, the D eff decreases more linearly than ∅ = 10 % at the beginning of the isotropy change, which indicates that small changes in isotropy in the particulate material modify it drastically; under these conditions the diffusion coefficient in the pore is predominant. (3) When the surface fraction is less than 50%, the D eff decreases more exponentially at the beginning and more linearly at the end of the isotropy change, which shows that small isotropy changes in the bar-aligned material drastically alter it. In this trend, diffusion in the agglomerate is less affected by isotropy. The proposed methodology can be used as a design tool to improve the mass transport in porous PEMFC electrodes. [ABSTRACT FROM AUTHOR]

Aluminosilicate (Al‐SiO2) thin films with vertically aligned mesochannels were successfully synthesized on Indium Tin Oxide (ITO) electrodes and employed for the immobilization of a cationic Ru(II) water oxidation catalyst without requiring linker groups. Optimal synthesis conditions yielded uniform mesoporous Al‐SiO2 films with tunable Al content, high surface area (568 m2/g), 3.94 nm pore size, and 155 nm thickness. Electrochemical studies confirmed the presence of the immobilized Ru complex undergoing diffusion‐controlled Ru(III/II) and Ru(IV/III) electron transfer. The Ru loading reached 4.71 nmol/cm2 at Si/Al=9.6, with higher Al content enhancing loading amounts via cation exchange. The Ru‐modified electrode exhibited high electrocatalytic water oxidation activity, achieving 75.3 % Faradaic efficiency and a turnover number of 298.6 for O2 evolution for 1 hour. This work provides a new approach to construct porous environments on an electrode surface to immobilize positively charged transition‐metal complexes as catalysts, offering potential applications in the development of electrocatalytic systems for energy conversion. [ABSTRACT FROM AUTHOR]

Due to their exceptional energy and power densities, 3D micro‐batteries emerge as highly promising candidates for miniaturized power sources. However, fabricating a complete and uniform electrolyte/separator membrane to separate 3D electrodes in assembled 3D batteries remains a significant challenge. Herein, the study presents a straightforward approach to preparing 3D electrolyte membranes via a modified spray‐deposition method. This 3D electrolyte membrane effectively isolates the 3D porous LiFePO4 cathode from the Li anode with a ionic conductivity of 9.6 × 10−4 S cm−1, facilitating the creation of an integrated aperiodic 3D battery. The 3D battery exhibits a specific capacity of up to 8.8 mAh cm−2 (29.1 mWh cm−2) and attains a maximum power density of 12.7 mW cm−2. The characteristic time is 0.17 s for 3D battery while 0.73 s for traditional 2D batteries. The enhanced rate performance with thick electrode is primarily attributed to the reduced ionic diffusion pathway. These results represent the highest peak power and energy density among all reported aperiodic 3D batteries. The utilization of spray‐deposited electrolytes for 3D electrode separation promises significant advancements in developing 3D batteries and demonstrates great potentials for practical applications. [ABSTRACT FROM AUTHOR]

This study focused on synthesis and characterization of super activated carbon/SnFe2O4 spinel nanocomposite as Li ion-battery soft electrode with high surface area. Various characterizations such as X-rays diffraction (XRD), UV–Vis spectroscopy, field emission electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), BET porosimeter analysis, vibrational sample magnetometry (VSM), and cyclic voltammetry (CV) were used to analysis the structural, optical, morphological, magnetic, and electrochemical properties of these nanocomposites. XRD analysis results indicate the presence of the SnFe2O4 phase and preferred peak in (311) plane for the super activated carbon/SnFe2O4 NPs nanocomposite. Various methods, such as Scherrer, Williamson–Hall, Rietveld, Halder–Wagner, and McMaille, were used to calculate structural parameters. FESEM images displayed the creation of very small structures with cubic and polyhedral shapes, showing cluster growth in SnFe2O4 phase. The most significant absorption of light was observed in the super activated carbon/SnFe2O4 sample in order of 105 cm−1. The band gap of the samples was found to be in the range of Eg = 2.54–4.70 eV, indicating that the materials exhibit semiconductor properties. Additionally, BET analysis revealed a notably high specific surface area of 2840.3 m2/g in the super activated carbon/SnFe2O4 nanoparticles nanocomposite. From the UV–Vis analysis, the values of refractive index (n), extinction coefficient (k), dielectric constant (ϵ ), Urbach energy (Eu), and reflection coefficient were studied. The analysis using VSM showed that nanoparticles exhibit ferromagnetic properties. FTIR analysis results confirmed the vibrations associated with the presence of metal oxides Sn–O and Fe–O. The existence of these metal oxide bonds suggests the formation of a tin ferrite spinel structure. The CV results demonstrate that lithium ions can penetrate the SnFe2O4 spinel structure due to the presence of the lithium salt electrolyte. [ABSTRACT FROM AUTHOR]

Cocaine is one of the most abused illicit drugs, and its abuse damages the central nervous system and can even lead directly to death. Therefore, the development of simple, rapid and highly sensitive detection methods is crucial for the prevention and control of drug abuse, traffic accidents and crime. In this work, an electrochemical aptamer-based (EAB) sensor based on the low-temperature enhancement effect was developed for the direct determination of cocaine in bio-samples. The signal gain of the sensor at 10 °C was greatly improved compared to room temperature, owing to the improved affinity between the aptamer and the target. Additionally, the electroactive area of the gold electrode used to fabricate the EAB sensor was increased 20 times by a simple electrochemical roughening method. The porous electrode possesses more efficient electron transfer and better antifouling properties after roughening. These improvements enabled the sensor to achieve rapid detection of cocaine in complex bio-samples. The low detection limits (LOD) of cocaine in undiluted urine, 50% serum and 50% saliva were 70 nM, 30 nM and 10 nM, respectively, which are below the concentration threshold in drugged driving screening. The aptasensor was simple to construct and reusable, which offers potential for drugged driving screening in the real world. [ABSTRACT FROM AUTHOR]

Carbon black, a key ingredient in ancient inks, is used today to make the porous electrodes found in many rechargeable batteries. Understanding how to control its microstructure can pave the way to better-performing batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors. [ABSTRACT FROM AUTHOR]

To overcome the significant volume expansion issue encountered by traditional silicon anodes in lithium‐ion batteries, this study employs chemical etching techniques to treat aluminum–silicon alloys of various ratios, successfully preparing three types of porous silicon electrode materials with different pore structures. Through a series of electrochemical tests, this article investigates the role of porous silicon structures in improving electrode performance. The results demonstrate that the porous silicon anodes exhibit superior cycle stability and rate capability compared to traditional solid silicon anodes. This confirms the effectiveness of the porous structure in mitigating the significant volume expansion during the charge and discharge process of silicon materials and in preventing premature electrode failure, thereby significantly enhancing the electrode's cycle life. Remarkably, the porous silicon with a high porosity rate shows exceptionally outstanding performance. Additionally, using computer simulations, this study also models the impact of changes in pore size within the porous silicon material at different states of charge and discharge on the stress distribution at the particle center and surface. These experimental and simulation results jointly provide strong empirical evidence for applying porous silicon materials as high‐performance anode materials for lithium‐ion batteries and offer essential guidance for future stress analysis and electrode design of porous silicon electrode materials. [ABSTRACT FROM AUTHOR]

Symmetrical solid oxide cells (SSOCs) are very useful for energy generation and conversion. To fabricate the electrode of SSOC, it is very time‐consuming to use the conventional approach. In this work, we design and develop a novel method, extreme heat treatment (EHT), to rapidly fabricate electrodes for SSOC. We show that by using the EHT method, the electrode can be fabricated in seconds (the fastest method to date), benefiting from enhanced reaction kinetics. The EHT‐fabricated electrode presents a porous structure and good adhesion with the electrolyte. In contrast, tens of hours are needed to prepare the electrode by the conventional approach, and the prepared electrode exhibits a dense structure with a larger particle size due to the lengthy treatment. The EHT‐fabricated electrode shows desirable electrochemical performance. Moreover, we show that the electrocatalytic activity of the perovskite electrode can be tuned by the vigorous approach of fast exsolution, deriving from the increased active sites for enhancing the electrochemical reactions. At 900 °C, a promising peak power density of 966 mW cm−2 is reached. Our work exploits a new territory to fabricate and develop advanced electrodes for SSOCs in a rapid and high‐throughput manner. [ABSTRACT FROM AUTHOR]

The effects of process parameters on the electroless plating of ionic polymer–metal composites (IPMCs) were studied in this work. Specifically, the NaBH4 reduction of platinum onto Nafion-117 was characterised. The effects of the concurrent variation of NaBH4 concentration, stir time and temperature on surface resistance were studied through a full factorial design. The three-factor three-level factorial design resulted in 27 runs. Surface resistance was measured using a four-point probe. A regression model with an R2 value of 97.45% was obtained. Surface resistance was found to decrease with increasing stir time (20 to 60 min) and temperature (20 to 60 °C). These responses were attributed to increased platinisation rates, resulting in more uniform electrode deposition, confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Surface resistance decreased, going from 1% to 5% NaBH4 concentration, but increased from 5% to 10% concentration. This behaviour was attributed to surface morphology: increased grain size inducing porous electrodes, in line with findings in the literature. The maximum tip displacement, measured through a computer vision system, as well as the maximum blocking force, measured through an analytical balance setup, were obtained for all 27 samples. The varying results were discussed with regards to surface and cross-sectional SEMs, alongside EDAX analysis. [ABSTRACT FROM AUTHOR]

With the rapid advancement of the new energy industry, porous electrode materials and complex electrolytes have gained widespread usage. Electrolytes exhibit distinctive phase behavior when subjected to the combined influence of confined space and electric fields. However, the measurement and prediction of such phase behavior encounter significant challenges. Consequently, numerous theoretical tools have been employed to establish models for phase equilibrium calculations. Nevertheless, current research in this field has notable limitations and fails to address the confinement of space or complex polymer electrolytes. Considering these shortcomings, an associating polymer density functional theory (PDFT) was developed by modifying excess free energy. This study examines the phase behavior of electrolytes with various chain lengths within diverse confined slits, revealing that the confinement effect and fluid tail chains can narrow the phase diagram. Additionally, a linear correlation between the electric field strength and the phase equilibrium offset has been identified, and a quantitative relationship is derived. The results of this investigation contribute to a deeper comprehension of complex fluid phase behavior and guide the design of electrochemical devices. [ABSTRACT FROM AUTHOR]

Miniaturized energy storage devices, such as electrostatic nanocapacitors and electrochemical micro-supercapacitors (MSCs), are important components in on-chip energy supply systems, facilitating the development of autonomous microelectronic devices with enhanced performance and efficiency. The performance of the on-chip energy storage devices heavily relies on the electrode materials, necessitating continuous advancements in material design and synthesis. This review provides an overview of recent developments in electrode materials for on-chip MSCs and electrostatic (micro-/nano-) capacitors, focusing on enhancing energy density, power density, and device stability. The review begins by discussing the fundamental requirements for electrode materials in MSCs, including high specific surface area, good conductivity, and excellent electrochemical stability. Subsequently, various categories of electrode materials are evaluated in terms of their charge storage mechanisms, electrochemical performance, and compatibility with on-chip fabrication processes. Furthermore, recent strategies to enhance the performance of electrode materials are discussed, including nanostructuring, doping, heteroatom incorporation, hybridization with other capacitive materials, and electrode configurations. [ABSTRACT FROM AUTHOR]

Abstract Recent advances in 3D printing have enabled the manufacture of porous electrodes which cannot be machined using traditional methods. With micron-scale precision, the pore structure of an electrode can now be designed for optimal energy efficiency, and a 3D printed electrode is not limited to a single uniform porosity. As these electrodes scale in size, however, the total number of possible pore designs can be intractable; choosing an appropriate pore distribution manually can be a complex task. To address this challenge, we adopt an inverse design approach. Using physics-based models, the electrode structure is optimized to minimize power losses in a flow reactor. The computer-generated structure is then printed and benchmarked against homogeneous porosity electrodes. We show how an optimized electrode decreases the power requirements by 16% compared to the best-case homogeneous porosity. Future work could apply this approach to flow batteries, electrolyzers, and fuel cells to accelerate their design and implementation.

In this paper, we present a continuation of our research on modeling electrolyte solutions within charged pores. We make use of the model developed by Blossey et al. [Phys. Rev. E 95, 060602 (2017)], which takes into account the structural interactions between ions through a bilinear form over the gradients of local ionic concentrations in the grand thermodynamic potential, as well as their steric interactions through the lattice gas model. The structural interactions may describe the effects of the molecular structure of ions at a phenomenological level. For example, these effects include steric effects due to non-spherical shapes of ions, their conformational lability, and solvent effects. In addition, we explore their specific interactions with the pore walls by incorporating external attractive potentials. Our primary focus is on observing the behavior of ionic concentration profiles and the disjoining pressure as the pore width changes. By starting with the local mechanical equilibrium condition, we derive a general expression for the disjoining pressure. Our findings indicate that considering the structural interactions of ions leads to a pronounced minimum on the disjoining pressure profiles at small pore widths. We attribute this minimum to the formation of electric double layers on the electrified surfaces of the pore. In addition, our results demonstrate that the inclusion of the attractive interactions of ions with the pore walls enhances this minimum and shifts it to smaller pore thicknesses. Our theoretical discoveries may be useful for those involved in supercapacitor electrochemical engineering, particularly when working with porous electrodes that have been infused with concentrated electrolyte solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rattan is converted to 3D current collector via a facile and cost-effective strategy. • The CR owns hierarchical structure, directional channels, and superior stability. • 3D MnO 2 cathode with a large mass loading of 10 mg cm−2 is successfully constructed. • Interfacial charge transfer kinetics can be significantly improved by 3D structure. • The cathode offers substantial areal capacity of 3.65 mAh cm−2 and good cyclability. Aqueous zinc-ion batteries (AZIBs) have emerged as prospective candidates for wide-scale energy storage, benefiting from their exceptional reliability and budget-friendliness. To tackle the challenge of limited energy density of AZIBs, it is pivotal to explore cathodes with substantial mass loadings. In this study, rattan is converted into a three-dimensional (3D) current collector with directional channels, high compressive strength, good electrolyte affinity, and superior electrochemical stability through a process involving ultraviolet light irradiation-assisted delignification followed by high-temperature carbonization. Using this current collector and a straightforward slurry pasting method, a 3D MnO 2 cathode featuring substantial loading amount of 10 mg cm−2 for active material can be constructed. This cathode's rich channel structure allows the carbon nanotube/MnO 2 composite material to establish full contact with the electrolyte, significantly facilitating interfacial charge transfer. The optimized cathode achieves an outstanding areal capacity of 3.65 mAh cm−2 at 0.1 A/g and sustains 1.52 mAh cm−2 at 1 A/g. Besides, the capacity retention remains at 60.2 % after 1000 cycles, even under such large mass loading. Notably, the fabrication procedure of the 3D cathode is simple, and the associated costs are relatively low compared to other 3D cathodes for AZIBs. These findings present an effective strategy for developing cost-effective and high-performance electrodes with large areal capacities, advancing energy storage technologies. [ABSTRACT FROM AUTHOR]

In the contemporary landscape of technological advancements, the burgeoning demand for portable electronics and flexible wearable devices has necessitated the development of energy storage systems with superior volumetric performance. Tungsten oxide (WO3), known for its high density and theoretical capacitance, is a promising electrode material for supercapacitors. However, low conductivity and poor cycling stability are still the key bottlenecks for its application. Herein, a novel composite comprising hollow porous WO3 spheres (HPWS) derived by template method was electrostatic self-assembled on the surface of the Ti3C2T x nanosheets. The resulting electrodes exhibited ultra-high volumetric capacitance of 1930 F cm−3 at 1 A g−1 and rate capability of 46% at 50 A g−1, attributed to enhanced ion accessibility from microporous structure and electron transport from conductive network of Ti3C2T x even at a high packing density of 3.86 g cm−3. Utilizing HPWS/Ti3C2T x as the negative electrode and porous carbon as the positive electrode, the assembled asymmetric supercapacitor achieved an energy density of 31 Wh kg−1 at a power density of 650 W kg−1 with over 107% capacitance retention after 5000 cycles. This work provides a promising approach for developing next-generation supercapacitors with ultra-high volumetric capacitance. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) performance of porous electrodes is critical for solid oxide fuel cells (SOFCs). However, the effects of gas diffusion on the ORR in porous media need further investigation, although some issues, such as nonthermal surface oxygen exchange, have been attributed to gas diffusion. Herein, La0.6Sr0.4Co0.2Fe0.8O3‐δ (LSCF) with various porosity, pore radii, and gas permeability were investigated via the electrical conductivity relaxation method and analysed via the distributed of characteristic time (DCT) model. The ORR is revealed with three characteristic times, which are gas diffusion, oxygen exchange via the surface corresponding to small pores, and oxygen exchange to large pores. Gas diffusion delays the oxygen surface exchange reaction, resulting in a very low chemical oxygen surface exchange coefficient compared with that obtained with dense samples under the assumption that all the surfaces are active for the ORR. Reduced surface area is thus defined to quantitatively represent the gas diffusion effects. The reduced surface area increases with increasing gas permeability, demonstrating the importance of electrode engineering for fast gas transport. Moreover, reduced surface area is suggested for replacing the specific surface area to calculate the electrode polarization impedance via the ALS model. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable energy solutions, zinc‐based flow batteries stand out for their potential in large‐scale energy storage, offering a blend of cost efficiency and safety. Although the porous electrode provides an increased specific surface area for reaction, the non‐uniform deposition of zinc, attributed to uneven concentration distribution within the porous electrode, has been a pivotal issue in accelerating the formation of zinc dendrites, which hinders the enhancement of energy density. A composite electrode with a strategic hierarchical pore structure has been developed with aligned nitrogen‐doped carbon fibers and traditional carbon felt. This structure takes advantage of the large pores of the carbon felt for efficient through‐flow paths, ensuring higher flow rates, while the dual‐scale pores within the electrospun film enhance mass transfer and increase the specific surface area. At 320 mA cm−2, it achieved an ≈11.4% improvement in the battery's energy efficiency. Moreover, the nitrogen doping and the optimized reaction uniformity within the composite electrode have been instrumental in reducing the generation of zinc dendrites. The battery, integrated with the innovative composite electrode, maintained an energy efficiency of 59.2% at 320 mA cm−2 after 300 cycles, which is a substantial improvement in operational longevity. [ABSTRACT FROM AUTHOR]

Organic potassium salts are the promising green activators for synthesizing porous carbon materials for energy storage. Herein, we report the synthesis of hierarchical porous carbon material derived from the mixture of soluble starch and ethylenediaminetetraacetic acid dipotassium salt dihydrate (EDTA‐2K) via carbonization and activation strategy. The sample is used as supercapacitors electrode, which exhibits superior mass specific capacitance (307.3 F g−1 at 1 A g−1), good rate performance (255.0 F g−1 at 10 A g−1), and excellent stability (retaining 83 % after 15000 cycles). This enhanced electrode performance is mainly due to the high specific surface area, the heteroatom co‐doping providing pseudo‐capacitance and the improved electronic conductivity. In addition, the asymmetric supercapacitor device shows a high energy density of 15 Wh kg−1 at the power density of 800 W kg−1 and capacitance retention of 90 % after 12000 cycles. [ABSTRACT FROM AUTHOR]

The sodium‐ion batteries (SIBs) are expected to be the substitute for lithium‐ion batteries (LIBs) because of their low cost, high abundance, and similar working mechanism. Among them, polyanion‐type electrodes show great application prospects due to their superior ion diffusion channels and structural stability. However, there are still many scientific issues that need to be thoroughly investigated, especially the formation mechanism, structural stability, and interface impedance of solid–liquid interfaces. Therefore, it is of great significance to systematically study the mechanism of interface reaction and the electrochemical behavior, to promote the further practical application of SIBs. Fortunately, the polyanionic electrodes can effectively improve the transport dynamics and the interfacial stability of the solid–liquid interfaces through constructing the porous structure, surface modification, and electrolyte strategies, thus improving the cycle and rate performance. This review discusses the characteristics and formation mechanisms of electrode/electrolyte interface (EEI), as well as their electrochemical behavior in porous structures with different dimensions. Furthermore, this review covers the application of porous materials in improving transport kinetics and EEI. In particular, it highlights the various strategies employed to comprehend the interplay among structure, chemistry, preparation methods, and the mechanisms of porous electrodes that ultimately affect the electrochemical properties of SIBs. [ABSTRACT FROM AUTHOR]

AbstractThe mechanical properties of the graphite electrode will dynamically change during the charge-discharge cycle, which will affect the propagation characteristics of guided waves in lithium-ion batteries. Meanwhile, lithium-ion batteries experience fluctuations in operating temperature during cycling, which will also influence the propagation of guided waves. This research aims to investigate the guided wave propagation problem of porous electrode material with electrolyte versus temperature. The problem is under the framework of Green-Naghdi theory and Biot theory, and a numerical approach is presented to solve the thermoelastic wave propagation characteristics in such a multi-layered porous electrode. A frequency domain simulation for a multi-layered porous anode will be established. The simulation results confirm the feasibility and accuracy of the proposed approach. The porosity of the anode material shows obvious dynamic variation during cycling, which illustrates a strong correlation with the elastic modulus of the solid skeleton. Then, the effects of porosity and temperature variations on the propagation characteristics of thermoelastic guided waves in multi-layered porous graphite electrodes will be analyzed in detail. The phase velocity of fundamental modes appears regularly shift in the low frequency range. This may provide theoretical support for the acoustic nondestructive characterization of the operating states of the lithium-ion batteries. [ABSTRACT FROM AUTHOR]

With the progressively widespread application of lithium‐ion batteries, their energy density and power density are being pursued to the extremely high. However, both cannot be reached simultaneously at present. Tortuosity depicts the relationship in ionic diffusion between bulk electrolyte and the electrolyte in a porous electrode, provides information about channels within electrodes, and correlates the current dilemma between energy density and power capability of the lithium‐ion batteries. It is crucial to upgrade the fast charging and discharging performance of LIBs electrodes without losing volumetric energy density and using tortuosity as a guide is able to achieve this goal fundamentally. Meanwhile, tortuosity can serve as an evaluation parameter for production quality assessment, but this demands a fast, accurate, and cost‐effective measuring method. After the definition and measurement of tortuosity are provided, this article analyzes the structural influencing factors of tortuosity which have impacts on ion transportation and subsequently on tortuosity to facilitate a more systematic and comprehensive picture. Through the discussion of contradictions and influencing factors, a more refined transmission line model (the refined TLM) is perceived as the very first step to drive both aforementioned goals toward success and is discussed in the perspective part. [ABSTRACT FROM AUTHOR]

A porous electrode material consisting of NiCo2O4/RGO with an approximate diameter of 200 nm has been successfully fabricated. This promising porous material was derived from ZIF-67/RGO (zeolitic imidazolate framework-67 crystals doped with reduced graphene oxide sheets) through an ion exchange and etching process using Ni(NO3)2·6H2O followed by a thermal reaction. The composition was analyzed using spectroscopic and morphological techniques. The obtained porous and hollow structure of NiCo2O4/RGO contains rich active sites. Additionally, its improved performance and stability were demonstrated using potassium ferricyanide (K3[Fe(CN)]6) (PFC) and sodium hydroxide (NaOH) as an electrolyte. NiCo2O4/RGO in NaOH/PFC exhibited a maximum estimated specific capacitance of 212.5 F g−1 at 0.5 A g−1 and demonstrated excellent retention value reaching 91.7% after applying 10,000 cycles at 20 A g−1. This symmetric supercapacitor achieved an outstanding energy density (Ed) of 75.54 Wh kg−1 at a power density (Pd) of 1.6 kW kg−1 at 0.5 A g−1. Surprisingly, there is a 2.5-fold enhancement in Ed (from 32.44 to 75.54 Wh kg−1) of NiCo2O4/RGO through the addition of 0.3 M PFC into 3 M NaOH. The results indicate that the NiCo2O4/RGO electrode could be ideal for supercapacitors. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis is the promising technical pathway of large‐scale green hydrogen production. However, its hydrogen evolution reaction (HER) is hindered by the alkaline environment, leading to slow H2O splitting kinetics, especially for NiMoCu alloy catalysts which are considered potential alkaline HER catalysts. In this work, the Ru‐substrate modified NiMoCu20 porous electrode is designed by a continuous multistep electrodeposition method. It shows the good alkaline HER performance at the high current density of 1000 mA cm−2, which is attributed to the synergistic charge‐reconfiguration effects between Ru‐substrate and NiMoCu alloy by density functional theory (DFT) calculations and in situ Raman spectra analysis. It indicates that the Ru‐substrate is capable of encouraging H‐OH* bond breakage and optimizing transition‐state H* adsorption. Further, the overall water electrolysis results of the alkaline water electrolysis cell (30 wt% KOH) at 70 °C show that it has good performance at the large current density of 1000 mA cm−2 with 2.05 V and good stability at 600 mA cm−2 up to 500 h. It provides the possibility of designing the high‐performance HER electrode from the view of industrial applications. [ABSTRACT FROM AUTHOR]

Carbon electrode‐based perovskite solar cells (C‐PSCs) without hole transport layer (HTL) have been emerging as a promising low‐cost photovoltaic technology with excellent stability for commercialization. However, the loose physical contact between the carbon electrode and perovskite layer, as well as the relatively poor conductivity of the carbon film, contributes mainly to the large gap in the power conversion efficiency (PCE) between C‐PSCs and the metal (Ag, Au, etc.,) electrode‐based counterparts. To this end, a simple but effective mechanical compression strategy for efficient C‐PSCs is developed. The mechanical compression densifies the porous carbon electrode for high film conductivity and also provides intimate contact between carbon and perovskite layers for fast charge extraction. Consequently, the resulting HTL‐free C‐PSCs using MAPbI3 (MA = methylammonium) absorber yield a PCE of 15.29%, corresponding to a 27.6% improvement compared to the counterpart without mechanical pressing treatment. Moreover, the compacted carbon film also serves as an enhanced barrier against the intrusion of water and oxygen, and the unencapsulated device retains 88.9% of its initial PCE after 1000 h of aging in ambient conditions with 35 ± 2% humidity. This work paves a simple and effective way toward efficient and stable C‐PSC. [ABSTRACT FROM AUTHOR]

Here, the hierarchical mesoporous-activated carbon particles obtained by KOH activation from pistachio shell wastes are modified by both the sulfonation process and CuO doping by hydrothermal heating (CuO@S-doped PSAC) for use as a supercapacitor. It is predicted that the electrochemical performance of the porous carbon electrode material obtained by such CuO doping and sulfonation process will be significantly increased with increased Faradaic capacitance. The electrochemical performance of CuO@S doped PSAC composite is systematically investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) in the presence of 1 M H2SO4, 1 M Na2SO4, and 1 M NaOH as electrolytes. The CuO@S doped PSAC-based electrode shows excellent stability with high specific capacitance up to 397.16 F/g at 0.1 A/g and 92.64% retention. Furthermore, FTIR, SEM, XRD, EDS, and nitrogen adsorption/desorption analyses are used for the characterisation of the obtained composites. Based on a significant supercapacitor performance, the synthesis strategy of carbon-based electrode material containing sulfonation and CuO modifications derived from agricultural biomass waste material is predicted to be a valuable example. [ABSTRACT FROM AUTHOR]

Highlights: A blade-coated composite paste, composed of a compressible 3D carbon skeleton, PEDOT:PSS, and CNTs, can naturally dry to form a porous electrode on paper with a micro- and nano-structured surface. The all-paper pressure sensor demonstrated an ultrahigh sensitivity of 1014 kPa−1, a wide responsive range up to 300 kPa, and an ultralow operating voltage of 0.01 V. The sensor showcased superior detection capability, ranging from subtle wrist pulses and robust finger taps to large-area spatial force. Flexible and wearable pressure sensors hold immense promise for health monitoring, covering disease detection and postoperative rehabilitation. Developing pressure sensors with high sensitivity, wide detection range, and cost-effectiveness is paramount. By leveraging paper for its sustainability, biocompatibility, and inherent porous structure, herein, a solution-processed all-paper resistive pressure sensor is designed with outstanding performance. A ternary composite paste, comprising a compressible 3D carbon skeleton, conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), and cohesive carbon nanotubes, is blade-coated on paper and naturally dried to form the porous composite electrode with hierachical micro- and nano-structured surface. Combined with screen-printed Cu electrodes in submillimeter finger widths on rough paper, this creates a multiscale hierarchical contact interface between electrodes, significantly enhancing sensitivity (1014 kPa−1) and expanding the detection range (up to 300 kPa) of as-resulted all-paper pressure sensor with low detection limit and power consumption. Its versatility ranges from subtle wrist pulses, robust finger taps, to large-area spatial force detection, highlighting its intricate submillimeter-micrometer-nanometer hierarchical interface and nanometer porosity in the composite electrode. Ultimately, this all-paper resistive pressure sensor, with its superior sensing capabilities, large-scale fabrication potential, and cost-effectiveness, paves the way for next-generation wearable electronics, ushering in an era of advanced, sustainable technological solutions. [ABSTRACT FROM AUTHOR]

Synopsis: This study presents a thiocyanogen-modulated alkali activation strategy for preparing N, S co-doped lignin hierarchical porous carbon (NSLHPC). Thiocyanate acts as a surface modulation mediator to introduce nitrogen and sulfur heteroatoms via oxygen replacement reaction. NSLHPC exhibits excellent electrochemical performance and long cycling lifespan in both symmetric supercapacitors and zinc-ion hybrid capacitors. [Display omitted] • Thiocyanogen-modulated alkali activation strategy for the preparation of NSLHPC. • Oxygen replacement reaction between KSCN and lignin carbon for N, S co-doping. • NSLHPC exhibits an impressive SSA of 2705.3 m2/g and a pore volume of 3.27 cm3/g. • NSLHPC presents remarkable electrochemical performance in aqueous supercapacitors. • DFT calculations reveal that N, S co-doping reduces the adsorption energy barrier of Zn2+. Constructing heteroatom-doped porous carbons with distinct charge storage properties is significant for high-energy–density supercapacitors, yet it remains a formidable challenge. Herein, we employed a thiocyanogen-modulated alkali activation strategy to synthesize N and S co-doped lignin hierarchical porous carbon (NSLHPC). In this process, thiocyanogen serves as a surface modulation mediator to substitute oxygen with nitrogen and sulfur species, while the combination of KOH activation and MgO template generates numerous nanopores within the carbon structure. The three-dimensional interconnected nanosheet architecture facilitates rapid ion transfer and enhances accessibility to active sites. Density functional theory (DFT) calculations demonstrate that introducing N and S heteroatoms through oxygen substitution reduces the adsorption energy barrier of Zn2+. Consequently, the optimized NSLHPC exhibits a remarkable specific capacitance of 438F/g at 0.5 A/g in 6 M KOH, delivering an energy density of 10.4 Wh/kg in the symmetric supercapacitor and an impressive energy density of 104.9 Wh/kg in the zinc-ion hybrid capacitor. The NSLHPC cathode also shows an excellent lifespan with capacitance retention of 99.0 % and Columbic efficiency of 100 % over 10,000 cycles. This study presents innovative strategies for engineering high-performance porous carbon electrode materials by emphasizing pore structure modulation and N, S co-doping as crucial approaches. [ABSTRACT FROM AUTHOR]

Biochar amalgamated from grass Desmostachya bipinnata was used for supercapacitors and microbial fuel cell applications. Herein, the nitrogen driven simple carbonization method at 800 C was used without activating agent for preparation of biochar material. The crystalline state, morphology, structural porosity, thermal properties, and vibrational surface area of the biochar were examined using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), Raman, Brunauer–Emmett–Teller (BET), thermogravimetric analysis/derivative thermogravimetry (TGA/DTG), and X-ray photoelectron spectroscopy (XPS), and the surface functional groups containing oxygen are assessed. The electrodes in supercapacitor and microbial fuel cells are developed from the functionalized biochar material. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies with 1 M H2 SO4 electrolytes and 1-ethyl-3-methylimidazoliu thiocyanate (EMImSCN) ionic liquid were conducted to compare the electrochemical properties of the fabricated supercapacitor. The primed electrodes unveiled augmented capacitance in1M H2 SO4 electrolyte as ~ 26 F/g in comparison to EMImSCN ionic liquid as ~ 22 F/g. The microbial fuel cell (MFC) emboding the primed electrode as cathode material exhibited a maximum open circuit voltage (OCV) about 819 ± 25 mV and a power density maximum of 0.78 ± 0.09 mW/m3. Significant removal of 77.14% was achieved in chemical oxygen demand (COD) of the effluent with an average effluent concentration of 1423 ± 25 mg/l. On the basis of the obtained results, we can predict that Desmostachya bipinnata can be a very suitable precursor for preparing carbon material for its use as electrode material for electrochemical energy system (energy conversion and energy storage) devices. [ABSTRACT FROM AUTHOR]

Designing and optimizing the pore structure of porous carbon electrodes is essential for diverse energy storage systems. In this study, an innovative approach spray phase‐inversion strategy was developed for the rapid and efficient fabrication of controlled porous carbon aerogel. Moreover, the aggregation structure of polyacrylonitrile is controlled by adjusting the Hansen's solubility parameter, thereby regulating the electrode material structure. Furthermore, the theoretical analysis of the spray phase‐inversion process revealed that this regulation process is jointly regulated by solvent hydrodynamic diameter and phase‐inversion kinetics. Through optimization, a novel porous carbon material was obtained that exhibited excellent performance as an electrode material. When utilized in supercapacitors for energy storage, it demonstrated a high specific capacitance of 373.1 F g−1 in a 6 M KOH electrolyte solution. Simultaneously, it has been observed that the preparation strategy for porous electrodes offers notable advantages in terms of excellent designability, broad universality, simplicity, and high efficiency, thereby holding promise for large‐scale fabrication of diverse porous electrode materials and various types of electrodes for diverse energy storage applications. [ABSTRACT FROM AUTHOR]

Thermo‐electrochemical cells (TECs) provide a new potential for self‐powered devices by converting heat energy into electricity. However, challenges still remain in the fabrication of flexible and tough gel electrolytes and their compatibility with redox actives; otherwise, contact problems exist between electrolytes and electrodes during stretching or twisting. Here, a novel robust and neutral hydrogel with outstanding stretchability was developed via double‐network of crosslinked carboxymethyl chitosan and polyacrylamide, which accommodated both n‐type (Fe2+/Fe3+) and p‐type ([Fe(CN)6]3−/[Fe(CN)6]4−) redox couples and maintained stretchability (>300%) and recoverability (95% compression). Moreover, poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) textile electrodes with porous structure are integrated into gel electrolytes that avoid contact issues and effectively boost the Pmax of n‐ and p‐type thermocell by 76% and 26%, respectively. The optimized thermocell exhibits a quick current density response and is continually fully operational under deformations, which satisfies the working conditions of wearable devices. Multiple thermocells (four pairs) are effectively connected in alternating single n‐ and p‐type cells in series and outputted nearly 74.3 mV at ΔT = 10°C. The wearable device is manufactured into a soft‐pack thermocells to successfully harvest human body heat and illuminate an LED, demonstrating the potential of the actual application of the thermocell devices. [ABSTRACT FROM AUTHOR]

Advancement of the voltage window with stringent safety concerns is an imperative strategy to enhance the energy densities and output power delivery of electrical double‐layer capacitors (EDLCs). Solid‐state, water‐in‐salt (WIS), and ionic liquid‐based electrolytes are attractive and ideal choices for high‐voltage EDLCs due to their superior voltage window, electrochemical performance, and predominant safety aspects. Mindful of this, the current report demonstrates the electrochemical performance of new nanoporous carbon electrodes derived from waste dry leaves of Swietenia macrophylla with a high specific surface area (SSA) (1834 m2 g−1) in polymer–gel, WIS, and ionic liquids‐based electrolytes. Symmetric EDLC devices are fabricated using polymer gel solid‐state (PVA–Na2SO4), ionic liquids (EMIMBF4), and WIS (21 m LiTFSI) electrolytes with the electrochemical stability windows of (ESW) 2, 2.5, and 2 V, respectively. The assembled devices with Na2SO4/PVA, EMIMBF4, and 21 m LiTFSI (WIS) electrolytes‐based devices exhibit high energy densities of 40, 31, and 25 Wh kg−1 at 0.5 A g−1 and good output power delivery of 5, 6.23, and 3 kW kg−1 at 5 A g−1 with better cyclability features. Self‐discharging studies and systematic evaluation of high‐voltage EDLCs offer a sustainable method to develop high‐performance aqueous and diverse electrolyte‐based supercapacitors. [ABSTRACT FROM AUTHOR]