Charge Storage Capacity Research Articles

Enhanced Performance of Lithium-Sulfur Batteries Using Construction Wastes: A Sustainable Approach to High-Loading Sulfur Cathodes.

Advancing lithium-sulfur battery technology requires addressing both extrinsic cell-fabrication and intrinsic material challenges to improve efficiency, cyclability, and environmental sustainability. A key challenge is the low conductivity of sulfur cathodes, which is typically managed by incorporating conductive carbon materials. These materials enhance the performance of sulfur cathodes by facilitating high sulfur loading and improving polysulfide retention. In line with green chemistry principles and circular economy concepts, this study explores the use of recycled materials-specifically recycled quartz and board-as substrates for graphene coatings in lithium-sulfur cells. Recycled quartz bricks and blocks, predominantly SiO2, and recycled shelf boards, rich in Al2O3, are successfully coated with graphene, which significantly improves polysulfide adsorption and overall battery performance. The graphene-coated quartz exhibits high sulfur loading (8 mg cm-2), exceptional charge-storage capacity (1,114 mA·h g-1), and long cycle stability (200 cycles) with an energy density of 19 mW·h cm-2. This approach enhances the electrochemical performance of the lithium-sulfur cells and also aligns with sustainability goals by repurposing waste materials and minimizing environmental impact. This novel methodology demonstrates that integrating recycled materials can effectively address key challenges in lithium-sulfur battery technology, advancing both performance and environmental sustainability.

Analysis of Galvanostatic Data from Electrochemical Capacitors

The ability to deconvolute charge storage mechanisms in electrochemical capacitor materials and systems is essential for understanding and improving behaviour. From an electrochemical perspective, this deconvolution can be achieved through an understanding of the expected response of a particular contribution. Voltametric measurements can be deconvoluted through the current response relative to the applied sweep rate. Herein we describe an analogous approach for galvanostatic data in which the charge or discharge time is related to the applied current (I). Specifically, capacitive charge storage is shown proportional to I−1, while diffusional processes are proportional to I2. Coupling this with a constant contribution from ohmic and residual charge storage processes allows for an effective approach to deconvolution for galvanostatic data. This is demonstrated with data from a glassy carbon electrode in non-aqueous electrolyte (an expected electrical double layer system) and from a manganese dioxide electrode in aqueous electrolyte (an expected pseudo-capacitive system).

Electrochemical oxidation-driven formation of nickel/nickel-based compounds on hollow carbon shells: Mechanistic insights and energy storage applications

Hydrangea-like nickel/nickel-based compounds decorated hollow carbon shells were synthesized through low-temperature calcination and a facile electrochemical oxidation process. This three-dimensional hollow hierarchical structure ensures intimate contact between the electrically conductive nickel (Ni) substrate and uniformly distributed electrochemically active nickel-based compounds. This hierarchical structure offers abundant active sites and accessible pathways, maximizing energy storage, particularly during rapid charge–discharge cycles. With 30 min of electrochemical oxidation, the optimized Ni-compound-based electrode exhibits a specific capacity of 643 C g−1 at 1 A/g. When assembled into a nickel-zinc battery cell with a zinc foil anode, the cell demonstrates swift current responses, with full capacity recovery even after a twentyfold increase in current density, followed by a return to 1 A/g. Density functional theory computations reveal that the electrochemical oxidation, conducted for an optimized duration, results in partial oxidation of Ni(OH)2, reducing the surface adsorption energy of OH− from the electrolyte and improving charge storage capacity.

Effect of CNF ratio and pressure on structural and electrochemical performance of hybrid hydrogel for flexible free-standing electrode and sensors

A 2D flexible hydrogel (GO/CNFn) with layered structure and superhydrophilic is synthesized via cross-linking and self-assembling of graphene oxide (GO) with cellulose nanofiber (CNF) through microwave-assisted hydrothermal. CNF acts as “dispersant” and “spacer”, making GO nanosheets uniformly disperse on their surface with less agglomerations. The carboxyl groups and hydrophilicity of CNF effectively improve the charge storage capacity of carbon materials through interactions. When the mass ratio of GO to CNF is 3:1, the GO/CNF1 exhibits an excellent comprehensive electrochemical performance as free-standing electrodes, with the specific capacitance reaching 295 F/g at 0.5 A/g in three-electrode system. The influence of press pressure on GO/CNFn reveals that increasing the pressure improves the hydrophilicity of the electrode, favoring their wettability to aqueous electrolyte. GO/CNF1–6 possesses the highest degree of graphitization, and delivers a highest mass specific capacitance up to 493 F/g at 0.5 A/g. Flexible solid-state symmetric supercapacitor with GO/CNF1–6 as electrodes exhibits an energy density of 20.6 Wh/kg at a power density of 250 W/kg. The good flexibility and biocompatibility of the devices show sensitive current response to biological signals, endowing them potential application prospect in wearable portable electronics and human motion detections.

Zeolitic imidazolate framework@graphene oxide nanocomposites for efficient supercapacitor electrodes

Despite advancements in nanoscale electrode materials, the pursuit of dependable, effective, and environmentally sound supercapacitors continues. This study explores the potential of zeolitic imidazolate framework@graphene oxide (ZIF@GO) nanocomposites as a viable option by revealing their improved electrochemical performance, including enhanced charge storage capacity and prolonged cycling stability. The ZIF-8@GO electrode exhibited an exceptional specific capacitance of 1372.67F/g at 1 A/g, indicating remarkable energy storage capacity. Furthermore, it showed exceptional cycling stability and durability by maintaining 96.02% of its capacitance after 20,000 cycles. To further evaluate ZIF-8@GO for energy storage, an asymmetric supercapacitor was assembled using the engineered electrode and activated carbon as the cathode and anode, respectively. The ZIF-8@GO nanostructure device demonstrated outstanding energy storage capability, maintaining a high specific capacitance of 165.29F/g at 1 A/g. Additionally, the device exhibited remarkable stability and endurance after 20,000 cycles, retaining 87.47% of its initial value. The promising electrochemical performance and ability of ZIF-8@GO nanocomposite to maintain capacitance across multiple cycles suggest a potential for advanced supercapacitor electrode materials.

A high-capacity and self-healable electrochromic system based on I0/CuI conversion reaction

Constructing electrochromic devices (ECDs) requires high-performance electrochromic electrodes with not only high color contrasts, but also large charge storage capacities. In this paper, a I0/CuI conversion-type electrochromic system is developed, achieving reversible and profound color switching between colorless transparent and dark brown, while delivering a large charge storage capacity of 246.7 mA h g−1. To improve switching durability, a multifunctional P10 (Polyquaternium-10) binder is introduced into the electrode, which can effectively confine the polyiodide intermediates and suppress the shuttle effect. At the same time, the CuI/Cu redox couple is further activated by controlling the applied voltage. The generated Cu from this couple can spontaneously react with residual I0 species and facilitate the conversion from I0 to CuI, and therefore in-situ rejuvenate the degraded electrochromic performance. Thanks to these rational designs, this electrochromic electrode achieves rapid response speeds (tcoloring: 14 s, tbleaching: 5 s), high optical modulation amplitude (73.4 % at 500 nm), decant coloration efficiency (57.0 cm2 C−1) and impressive cycle stability (without performance degradation after 150 cycles). This work provides a novel electrochromic system for the construction of high-performance electrochromic devices.

Electrodeposition of Manganese (III) Phthalocyanine/ Reduced Graphene Oxide for Asymmetric Supercapacitor Devices.

In this study, two novel tetra-substituted manganese (III) phthalocyanines bearing (9H-carbazol-2-yl)oxy groups on peripheral (1) or non-peripheral (2) positions were prepared and used for modification of reduced graphene oxide (rGO) by applying a simple one-step electrodeposition technique for the first time. The manganese (III) phthalocyanines (MnPcs) were electropolymerized and graphene oxide was electrochemically converted into reduced graphene oxide simultaneously. Subsequently, an rGO-MnPc hybrid structure was formed directly on the NiF electrode (substrate) via layer-by-layer assembly. Additionally, the effect of substituent position on the charge storage capacity of the prepared hybrid capacitive candidates was investigated. The fabricated hybrid electrodes exhibited remarkable electrochemical performance due to the combination of manganese (III) phthalocyanines and reduced graphene oxide. The NiF/rGO2-2 electrode exhibited the highest specific capacitance (512.4 F g-1) at 0.5 A g-1 and the remained specific capacitance was obtained 88.1 % after 5000 consecutive charge-discharge cycles. An asymmetric supercapacitor (ASC) was constructed from rGO2-2 as the positive electrode and rGO as the negative electrode with a working potential of 1.5 V. The as-prepared device delivered a specific energy of 17.4 Wh kg-1 at 350 W kg-1. Hence, manganese (III) phthalocyanine-reduced graphene oxide electrodes can be considered outstanding materials for energy storage applications in the future.

Acetylacetonate-modified TiO2 nanoparticles coated on the carbon felt as the negative electrode of vanadium redox flow battery for reducing HER and enhancing V3+/V2+ redox reactions

The occurrence of the hydrogen evolution reaction (HER) on the surface of the carbon-based negative electrode of the vanadium redox flow battery (VRFB) causes high charge transfer resistance (RCT) for the desired V3+/V2+ redox reaction leading to irreversible capacity loss. To this effect, we have synthesized acetylacetonate-modified TiO2 (SGTA) and unmodified TiO2 (SGT) coating colloidal solutions as electrocatalysts for enhanced V3+/V2+ redox reaction on the carbon-felt negative electrodes of VRFB. The SGTA particles exhibit significantly higher homogeneity with sizes of ≤15 nm, in comparison to the severely aggregated SGT particles with diameters of ∼23–75 nm in colloidal solution. When coated on the pristine carbon felt (P-CF), the surface morphology of the SGTA@CF electrode exhibits relatively dense, uniformly coated particles, in comparison to the sparse, non-even coating of aggregated particles on the SGT@CF electrode surface. Consequently, the charge transfer for V3+ → V2+ reduction reaction and charge storage capacity are determined to be in the order SGTA@CF > SGT@CF > P-CF, confirming that the competitive and irreversible HER was higher on the surface of non-evenly coated fibers and bare carbon felt, respectively.

V2O5-MnO2 nanocomposites as an efficient electrode material for high-performance aqueous supercapacitors

Redox-active supercapacitors are very interesting due to their high energy density (>25 Wh kg−1 at device level) and redox charge storage mechanism. In this work, V2O5-MnO2 nanocomposites are synthesized by a scalable hydrothermal approach. MnO2 in V2O5 provides better structural stability with reasonable electrochemical performance, in which V2O5 enhances the cyclic stability and rate capabilities. The V2O5-MnO2 -based electrodes deliver a specific capacitance of 266 F g−1 at 0.5 A g−1 and are stable up to 6500 cycles with 97 % capacitance retention at 5 A g−1. The kinetic study depicts that composite electrodes have a 64 % diffusive and 36 % capacitive charge storage contribution to the overall charge storage at 1 mV s−1. In symmetric full cells, the composite materials show a wide active potential window of 2.5 V and retain 83 % capacitance after 10000 continuous GCD cycles at an applied current density of 2 A g−1. The promising charge storage performance is due to a suitable conducting matrix and the effective coating of MnO2 nanoparticles over the unique V2O5 niddle shape (two-dimensional) micro-rods.

Innovative Core–Shell Tubular Structure in Polymer/Manganese–Nickel Oxide/Carbon Nanotube Blends for Electrochemical Components

ABSTRACTTo address the issue of electrochemical performance degradation resulting from redox reactions during the charging and discharging of supercapacitors, we introduced a novel electrode material featuring a core–shell attachment structure (PANI@(MnO2 + NiO)) with the incorporation of carbon nanotubes (CNTs). The introduction of CNT on top of the core–shell structure by a simple chemical synthesis method helps to improve the double‐layer capacitance and Faraday capacitance of the composite. Thus, multiple synergistic effects can be produced to improve charge storage capacity. The morphology structure and electrochemical properties of PANI@(MnO2 + NiO)@CNT were analyzed. In a three‐electrode configuration, the specific capacitance of the composite is 327 F g−1 at a current density of 0.5 A g−1. Remarkably, the capacitance retention rate exceeded 75% after 5000 charge–discharge cycles. Calculations indicate that in a supercapacitor employing a 1 M Na2SO4 electrolyte, the composite demonstrated energy and power densities of 48.1 W h kg−1 and 999.9 W kg−1, respectively. This kind of core–shell structural composites achieved electrochemical properties in line with expectations through a simple chemical synthesis method. As a practical application of supercapacitor electrode materials, PANI@(MnO2 + NiO)@CNT have better electrical properties than similar materials and have broad application prospects in industrial production.

Simulation and experimental investigation of electret polypropylene fiber preparation via centrifugal melt electrospinning for enhanced air filtration

Rapid urbanization and industrialization have led to severe air pollution, enabling bacteria and viruses to become suspended in aerosol particles, which can be inhaled and pose a significant threat to human health. Electrostatic filtration offers a solution to enhance filtration efficiency without increasing resistance. However, traditional electret methods involve the usage of toxic solvent evaporation, and electret filter materials like polypropylene (PP) often suffer from rapid charge dissipation. In this study, we combined centrifugal melt electrospinning with Dissipative Particle Dynamics simulations to achieve continuous electret production and investigate the influence of experimental conditions and polymer additives on the charge-trapping capability of PP fibers. The results show that centrifugal melt electrospinning significantly enhances the charge storage capacity of PP fibers. The α crystal form of PP enhances electret performance by generating more effective charge traps, and experimental parameters influence electret performance by altering crystal forms. Additives effectively promote charge stability, resulting in stable voltages up to 11.09 kV with 1.5 wt% electret additive. Moreover, our study elucidates the correlation between crystal structure and electret performance, providing valuable data for regulating electret PP fibers.

Improving Electrochemical Performance in Planar On-Chip Zn-ion Micro-Batteries via Interlayer Strategies.

The imperative development of planar on-chip micro-batteries featuring high-capacity electrodes and environmentally safer, cost-effective, and stable systems is crucial for powering forthcoming miniaturized systems-on-chip smart devices. However, research in the area of high-stability micro-batteries is limited due to the complex fabrication process, the stability of micro-electrodes during cycling, and the challenge of maintaining higher capacity within a limited device footprint. In response to this need, this study focuses on providing highly stable and high-capacity micro-electrodes. This involves adding a PEDOT layer between the electrode material and the current collector, applied within a planar polyaniline cathode and zinc anode device structure to enhance charge storage performance. This straightforward strategy not only improves device stability over long-term cycling and reduces charge transfer resistance but also increases charge storage capacities from 17.64 to 19.75 µAhcm- 2 at 0.1 mAcm- 2. Consequently, the Zn-ion micro-batteries achievenotable peak areal energy and power of 18.82 µWhcm- 2 and 4.37 mWcm- 2, respectively. This work proposes an effective strategy to enhance the electrochemical performance of planar micro-batteries, a critical advancement for the development of advanced portable electronics.

Physical and electrochemical performance of Mn-doped zinc oxide electrode material for asymmetric supercapacitor

Manganese-doped zinc oxide has emerged as a promising material for high-performance supercapacitors (SCs) due to its enhanced electrochemical properties, including improved charge storage capacity and cycling stability. Pristine Zinc oxide (ZO) and Manganese (Mn) doped (2 wt % and 4 wt %) zinc oxide (hereby labeled: ZO, 2MZO, and 4MZO) derivatives have been synthesized via an aqueous sol-gel-based co-precipitation method. The physical characterizations of synthesized samples have been performed using TGA, XRD, FESEM, and BET. The XRD has confirmed the phase pure hexagonal wurtzite structure synthesis of ZO, 2MZO, and 4MZO samples. The FE-SEM images revealed that synthesized material had shown the mixed morphology as polyhedral particles, rods, and flakes in the nano region. Mn-doped has increased specific surface by 132 % compared to bare ZO. The electrochemical characterization techniques, including CV, GCD, and EIS, have been used to access electrochemical parameters using an aqueous 4 M KOH electrolyte. A detailed CV analysis was also carried out to investigate the capacitive contribution of the material in cycling. The electrochemical characterization techniques (CV, GCD, and EIS) have been performed to access electrochemical parameters using an aqueous 4 M KOH electrolyte. The 4MZO electrode material has shown an enhancement in specific capacitance (164.28 Fg-1) compared to pristine ZO (42.83 Fg-1). The EIS study revealed that the 4MZO has the lowest internal impedance 0.30 Ω compared to 0.70 Ω, and 2.60 Ω for 2MZO and ZO, respectively.

Adsorption and energy storage characteristics of ionic liquids in porous zeolite-templated carbon materials

The energy storage capacity of supercapacitors is closely related to the capacity of their electrode materials to adsorb electrolytes. Porous zeolite-templated carbon (ZTC) materials are a type of porous carbon material with a well-defined spatial structure and are thus promising electrode materials. This study utilizes molecular dynamics simulations to compare the ion number density and charge density distributions of the [EMI][BF4] ionic liquid for various ZTC materials, while also examining the ion adsorption characteristics for different electrode charges. Parameters such as the degree of confinement (DOC) and the charge compensation per carbon (CCpC) are introduced to represent the ion adsorption and charge storage capacity of the materials, with a higher DOC indicating a greater number of encapsulated ions and a higher CCpC indicating a more efficient charge storage. The findings suggest that materials with a larger pore size tend to exhibit increased ion adsorption. However, many CCpC adsorption sites that can store more charge are then found in positions with a smaller DOC. This work unveils the ion adsorption characteristics of ZTC materials in charged electrode and presents the differential capacitance curves of various materials, thereby providing a theoretical foundation for the utilization of ZTC materials as electrodes in supercapacitors.

Insights into the electrochemical performance of manganese dioxide coated metallic foils as potential electrodes for supercapacitors

AbstractManganese dioxide (MnO2) is a promising electrode material for supercapacitors due to its high theoretical specific capacitance. In this study, MnO2 particles were synthesized using a simple hydrothermal method and subsequently coated onto silver, nickel, and aluminum foils via dip coating. The structural, morphological, and functional properties of the resulting MnO2 nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT–IR). Electrochemical impedance spectroscopy (EIS), galvanostatic charge–discharge (GCD), and cyclic voltammetry (CV) were employed to investigate the electrochemical performance of the coated metallic foils. The results demonstrated that MnO2/Ag foils exhibited the highest specific capacitance of 198 F g–1 at a scan rate of 0.25 A g−1, accompanied by excellent cycle stability (89% capacitance retention). This performance surpassed that of MnO2/Ni and MnO2/Al foils, which exhibited maximum specific capacitances of 150 and 101 F g−1, respectively. Additionally, MnO2/Ag foils displayed the highest charge storage capacity, as evidenced by EIS analysis, reaching 4000 Ω, nearly double that of MnO2/Ni and MnO2/Al foils. These findings highlight the potential of cost-effective and high-performance MnO2/Ag foils for widespread applications in energy storage devices such as electrochemical capacitors. Graphical Abstract

Research on faradic capacitive deionization regeneration method for absorption air conditioning system

The development of renewable energy driven air conditioning system is of importance for curbing the CO2 emission. Absorption air conditioning systems could be a good choice but for its low regeneration efficiency. Capacitive deionization (CDI) regeneration method has been proposed to improve the efficiency of absorption system by eliminating the energy waste in the traditional thermal regeneration method. The core part of CDI is the electrode normally made from porous carbon materials, which often suffers from low charge storage capacity and co-ion repulsion. On the purpose of performance optimization, this paper proposes a hybrid deionization (HCDI) regeneration method by fabricating the electrode from Faraday materials. Experimental research has been made on the regeneration capacity of the prepared electrodes. Investigation has been conducted on the performance of the HCDI method based absorption system. The influence of different parameters has been revealed. Compared with the porous carbon electrode, the Faraday electrode has raised the charge efficiency by 20%, and raised both the regeneration capacity and overall performance by 40%. Under optimized working conditions, the COP of the HCDI based absorption system has reached 3.51 in the experiments, which shows great potential for future application.

Effect of charge-discharge with higher capacitance performance of Ni-substituted CoFe2O4 magnetic nanoparticles for energy storage

In this work, we synthesized NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) magnetic nanoparticles (MNPs) by using ultrasonication-assisted reverse chemical co-precipitation method. The X-ray diffraction (XRD) patterns confirm the single-phase with mixed spinel structure of the NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs with the crystallite size range between 12 nm - 17 nm. The molecular dynamics and oleic acid coated Ni-substituted CoFe2O4 magnetic nanoparticles were confirmed by FTIR measurements. The surface composition of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs (Ni, Co, Fe and O) and their oxidation states were estimated using X-ray photoelectron spectroscopy. The NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs are spherical in shape and polycrystalline in nature, confirmed by FESEM and HRTEM measurements. The Ni-substituted CoFe2O4 MNPs with higher zeta potential (ζ) from −24 mV to -41 mV with an increase in Ni concentration, signifies the stable colloidal stability due to the electrostatic repulsion between MNPs. The DC magnetization (M-vs-H) measurements reveal the ferrimagnetic behavior of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs, which suppress the saturation magnetization (MS) from 48.6 emu/g to 5.3 emu/g with the enhanced coercivity (HC) from 335 Oe to 1700 Oe with the substitution of Ni2+ ions is in corroboration with electron paramagnetic resonance (EPR) measurements. The enhanced EPR resonance field (Hres = 2335 Oe - 3261 Oe) with the substitution of Ni2+ ions is attributed to the generation of oxygen vacancies and defects, which are predominant in Ni0.8Co0.2Fe2O4, resulting in significantly enhanced electrochemical performance. Therefore, the three-electrode system was utilized to investigate the electrochemical properties of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs. The Ni-substituted CoFe2O4 MNPs have demonstrated significantly enhanced capacity retention of 77 % even after 5000 cycles in 1 M H2SO4 electrolyte solution. NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs exhibit an excellent specific capacity (Cs) of 794.5 F/g at a current density of 1 A/g, signifies the rate of redox reaction at surface electrolyte interface (SEI) is greatly influenced by the surface to volume ratio. Thus, with the enhancement of Ni2+ ions, redox reaction kinetics might become more efficient resulting in the enhanced charge storage capacity.

Electrochemical analysis of sol-gel and hydrothermal synthesized mesoporous strontium titanate spherical nanoparticles as electrode material for high-performance flexible supercapacitors

Perovskite oxides with large specific surface areas present a promising avenue for enhancing supercapacitor efficiency. This study investigates the remarkable charge storage capabilities of strontium titanate (SrTiO3, STO) synthesized via sol-gel and hydrothermal techniques for electrochemical energy storage applications. The cubic crystal structure of STO, confirmed from X-ray Diffraction analysis, synthesized at lower temperatures through both methods, provides three-dimensional diffusion channels for oxygen anion movement, which is crucial for improving charge storage capacity. X-ray photoelectron spectroscopy confirmed the elements’ oxidation states and their spin-orbit splitting. The spherical nanoparticle morphology was observed in the FESEM images, BET characterization revealed a high specific surface area contributing to more charge storage and mesoporous nature facilitates excellent mass transfer rates of electrolytic ions. Electrochemical measurements and calculations confirmed that sol-gel and hydrothermally synthesized STO electrodes exhibit maximum specific capacitances of 130 F g−1 and 156 F g−1 at 10 mV s−1, respectively. A fabricated flexible supercapacitor device in an aqueous medium maintains a constant voltage of 1.2 V, capable of powering a digital watch. Hence, this study demonstrates the potential of STO electrode-based supercapacitors for a wide range of electrochemical energy storage applications.

Impact of microelectrode geometry and surface finish on enzymatic biosensor performance

Food production, environmental protection, biotechnology, and medicine, all depend on biosensors for measuring specific biological molecules. Among biosensors, enzymatic electrochemical biosensors have received particular attention due to their simple operation and enzymes’ inherent specificity. Researchers have extensively explored novel materials and biological designs to improve performance (i.e., sensitivity, linearity, limit of detection, and response time). However, in comparison, physical and geometrical design has not received the same attention. To this end, we compared platinum (Pt) microelectrodes with circular or fractal geometry with the same surface area (2D geometry). We also studied the effect of 3D geometry by nanostructuring both circular and fractal microelectrodes via electroplating Pt black. Fractal Pt black microelectrodes displayed the highest current density, charge storage capacity, and sensitivity towards H2O2. Next, we immobilized glucose oxidase onto various microelectrode geometries by microcontact stamping. Fractal Pt and Pt black glucose biosensors were 91.7% and 83.3% more sensitive than circular counterparts. Circular and fractal Pt black glucose biosensors were 63.0% and 55.9% more sensitive than Pt counterparts. Fractal geometry also provided better linearity and limit of detection. We modified enzyme layer thickness through multiple layer stamping and found a trade-off whereby increasing thickness increased sensitivity but also increased response time. Lastly, we developed a COMSOL Multiphysics numerical model to interpret the amperometric data and the impact of physical design on critical parameters. The work here will serve as a guideline for improving enzymatic electrochemical and other biosensors via physical design, which is simpler to modify than material or biological design.

Pr2CuO4/MWCNT/MXene/PANI: A novel quaternary composite with tunable properties for potential applications in optoelectronics and energy storage devices

Pr2CuO4/MXene/MWCNT and PANI composites were synthesized for symmetric supercapacitor applications using a simple hydrothermal and in-situ polymerization technique. Pr2CuO4/ MXene/MWCNT and PANI were of ratios 40:60 (PC1), 50:50 (PC2), and 60:40 (PC3). Composites had a tetragonal single phase of Pr2CuO4 with a preferred orientation peak along (103) plane. FTIR confirmed functional bands of all constituents of the composite. Porous morphology was confirmed by scanning electron microscopy (SEM) beneficial for energy storage capacity. The PC2 Composite possessed the widest absorption range and the smallest band gap energy. The dielectric constant of PC2, was the highest than pure Pr2CuO4 and the other composites. Coercivity and saturation magnetization for the composites decreased with decreasing Pr2CuO4 percentage, producing less eddy currents, which reduced energy dissipation and contributed to the increased efficiency of capacitors and inductors. The best ratio of Pr2CuO4/ MXene/MWCNT and PANI was 50:50 for increasing rate capability. This ratio enhanced surface area, charge storage capacity, specific capacity, and impedance behaviour. The optimized PC2 (Pr2CuO4/MXene/MWCNT: PANI 50:50) electrode exhibited exceptional electrochemical performance, achieving volumetric and gravimetric capacitance values of 2611.47 Fg−1 at 2 Ag−1. This enhanced performance can be explained by the combined effects of Pr2CuO4/MWCNT/PANI, which actively promoted pseudocapacitance and impeded MXene restacking. An excellent candidate for advanced energy storage systems, the electrode has an energy density of 58.032 Whkg−1 and remarkable rate capabilities.