Graphite Layers Research Articles

Spatial‐Dependent Coupling of Electrochemistry, Mass Transport, and Stress in Silicon‐Graphite Composite Electrodes for Lithium‐Ion Batteries

AbstractThe commercialization of high‐capacity silicon materials in lithium‐ion batteries is hindered by significant volume changes. Composite anodes made from silicon and graphite, which increase battery capacity and maintain electrode structural stability, are receiving considerable attention. However, the spatial configuration of the active particles in the electrode is few investigated due to the complexity of experiments at the microscopic scale. Herein, this work focuses on electrochemical, mass transport, and stress coupling mechanisms by considering different spatial configurations of silicon and graphite. In situ electrochemical and stress measurements are first conducted to demonstrate the impact of the active material arrangement. Then, a 2D electrochemical‐mechanical model is developed considering the heterogeneity of electrochemical processes at the particle‐electrolyte interface. The results show that placing silicon in the upper active layer significantly reduces the ion transport resistance, while the graphite layer near the current collector provides a good conductive network for electron transport in the silicon layer, enhancing the performance of the composite electrode structure. By combining electrochemical and mechanical field models with experimental verification, this study deepens the understanding of composite electrode structure design, offering practical guidance for optimizing the spatial configuration of electrode materials to significantly improve battery performance.

Cascaded utilization of magnetite nanoparticles@onion-like carbons from wastewater purification to supercapacitive energy storage.

Developing high-performance carbon-based materials for environmental and energy-related applications produces solid waste with secondary pollution to the environment at the end of their service lives. It is still challenging to utilize these functional materials in a sustainable manner in different fields. In this study, we demonstrate a cascaded utilization of an Fe3O4@onion-like carbon (Fe3O4@OLC) structure from wastewater adsorbents to a supercapacitor electrode. The structure was formed by carbonizing Fe3O4@oleic acid monodisperse nanoparticles into interconnected Fe3O4@OLCs and subsequent insufficient acid etching. The hollow OLCs in the outside region of the hybrid structure provide high surface area and the encapsulated Fe3O4 nanoparticles in the inside region offer high ferromagnetism. The three-dimensionally interconnected graphitic layers are advantageous for efficient separation and high conductivity. As a result, the maximum saturation adsorption capacity of insufficiently etched interconnected Fe3O4@OLCs can reach up to 90.2 mg g-1 and they can be efficiently separated under a magnetic field. Furthermore, the hybrid structure is thermally transformed into N-doped HOLCs, which are demonstrated to be a high-performance supercapacitor electrode with high specific capacitance and high electrochemical stability. The cascaded utilization of the hybrid structure in this study is meaningful for eco-friendly development of functional materials for environmental and energy storage applications.

High‐Performance Na‐Storage and Sodiation Behavior Identification in Cellulose‐Derived Hard Carbon by High‐Resolution Element Mapping Microscopy

Nowadays, hard carbon is one of the most promising anode materials for sodium‐ion batteries. However, the Na‐storage performance of hard carbon varies for different precursors and synthetic processes due to disparities in the dopant content, dimensions, and categories of defects, graphitic domains, which lead to controversial explanations for the energy storage mechanism. Herein, self‐freestanding membrane of cellulose‐derived carbon fibers is presented, delivering a reversible Na‐storage capacity of 330 mAh g−1 at 50 mA g−1 due to abundant ordered graphitic zones with enlarged interlayer spacings around 0.39 ± 0.03 nm. Benefiting from a robust solid electrolyte interphase layer rich in NaF nanocrystals, the membrane also holds a superior rate capability of 100 mAh g−1 at 2 A g−1 and long‐term cycling stability with capacity retention of 82.6% at 1.5 A g−1 for 4000 cycles. A clear sodiation behavior of Na+ intercalation into enlarged carbon graphitic layers at the slope step above 0.10 V and Na cluster evolution in the micropores at the plateau step around 0.01–0.10 V is disclosed by high‐resolution element mapping microscopy, different from the accepted mechanism of Na+ intercalation into graphitic layers at the plateau step.

Operando Investigation of Al Plating Regimes on HOPG in [EMImCl]:AlCl3 by Electrochemical Reflection Anisotropy Spectroscopy

Rechargeable aluminium batteries show promise as next‐generation systems with a more abundant material base than lithium technology. However, the stable native oxide on top of aluminium metal electrodes leads to poor cell performance. Graphite, on the other hand, is a so far rarely investigated alternative that can be used as both the anode and cathode. Here, metallic aluminium is deposited at the anode, while AlCl4– is intercalated at the cathode. For both cases, understanding the electrode–electrolyte interface is crucial for improving the performance of the battery. In this work, we use reflection anisotropy spectroscopy to study the evolution of the interface under applied potentials. We find that the cathode exhibits an irreversible swelling of the top‐most graphite layer due to AlCl4– intercalation as well as the formation of an SEI during the first voltammetry cycle. On the anode, the electrodeposition of aluminium is initially well‐ordered. However, the evolution of the surface morphology depends on the applied potential, with island‐like growth at less cathodic potentials, and layer‐by‐layer growth at more anodic potentials. With the optical operando spectroscopy, we can follow these qualitatively different plating and stripping regimes in a time‐resolved manner.

Microwave-treated layered graphite for highly efficient solar-powered seawater desalination and wastewater treatment

In the midst of the global water crisis, the ‘waste-to-treasure’ strategy, which includes desalination and wastewater recycling, is proving to be a promising approach. However, existing solar evaporators are hampered by challenges such as low photothermal conversion efficiency and significant heat losses. Here, we present an innovative solution that reduces the band gap of the material and improves the efficiency of light recycling. As a result, the microwave-treated graphite achieves a 15 % reduction in reflectivity and a 9 °C increase in surface temperature. In addition, the integration of this graphite with a hydrogel to modulate the interfacial wettability further optimizes the evaporation efficiency. When exposed to sunlight, the developed cone column evaporator achieves an impressive evaporation rate of 2.91 kg m−2 h−1, which is a significant increase of 663 % over the natural evaporation rate of a 3.5 wt% NaCl solution. Remarkably, no salt deposits were observed on the surface of the evaporator during the tests and the material exhibited excellent adsorption and desorption properties for pollutants, highlighting its potential for sustainable applications. These results provide valuable theoretical and practical insights for the design and development of high-efficiency solar evaporators.

Highly-dispersed CdS nanoparticles coating hierarchical Ni@NC derived from ultrathin nanosheets NMOF-Ni: Photocatalytic hydrogen evolution coupled with alcohol oxidation

Photocatalytic water-splitting into H2 in conventional procedures often requires sacrificial agents to consume unutilized holes to boost the reaction. Herein, we cast off the dependence on the addition of sacrificial agents and develop a dual-functional photocatalyst CdS/Ni@NC for coupling H2 evolution with value-added benzyl alcohol (BA) oxidation in anaerobic aqueous solution, wherein CdS/Ni@NC was synthesized by in-situ anchoring of CdS nanoparticles (NPs) onto NMOF-Ni ultrathin nanosheets-derived nitrogen-doped wrinkled graphitic carbon layers encapsulated metallic Ni NPs (Ni@NC). The optimized photocatalyst CdS/Ni@NC(5) achieves a high visible-light-driven H2 evolution rate of 1881 μmol·g−1·h−1 and a benzaldehyde (BAD) yield of 3254.2 μmol·g−1·h−1, with nearly 100 % selectivity over a 6 h period, which are 32.6 and 10.5 folds of that for CdS alone, respectively. Further in-depth experimental characterizations reveal that the hierarchical Ni@NC serves as an ideal support to enable high dispersion of CdS NPs, thus improving light absorption and facilitating full contact with reactants. Besides, the widely distributed Ni NPs, effectively shielded by nitrogen-doped wrinkled graphitic carbon layers, can not only promote photogenerated charge transfer for enhanced H2 production but also facilitate the cleavage of the Cα–H bond in BA, contributing to achieving high aldehyde selectivity. This study, integrating carbonized ultrathin nanosheets NMOF-Ni with CdS to synergistically enhance surface redox reactions, holds significant promise for advancing the development of high-performance photocatalysts for integrated production of solar hydrogen and value-added solar chemicals.

Detection of piperine content in black pepper using a molecular imprinted poly(N,N-dimethylacrylamide) embedded graphite electrode: A machine learning based prediction approach

The paper presents a molecular imprinted graphite electrode for selective and sensitive detection of piperine (1-Propylpiperidine) in Piper nigrum (black pepper). Poly(N,N-dimethylacrylamide) (PDMAM) was utilized as a functional monomer directing polymerization of uniform molecularly imprinted polymer (MIP) layers on the surface of the graphite layer using ethylene glycol dimethacrylate (EGDMA) as cross-linker with piperine (PIP) as template molecules. The formation of imprinting, non-imprinting, and elution of analytes within the polymer matrix were studied by field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR), UV–visible (UV–Vis) and X-ray photoelectron spectroscopy (XPS). The electrochemical response of piperine was evaluated through differential pulse voltammetry (DPV) using a PDMAM-MIP@G electrode that showed an oxidation peak at 1.25 ± 0.15 V. Under optimized experimental conditions, DPV peak currents were linear over two concentration ranges (0.001–1 µM and 1–200 µM). A limit of detection (LOD) was found to be 0.0006 µM. Developed electrode yielded high selectivity, sensitivity (12.92 µA/µM (lower linear range) and 0.33 µA/µM (upper linear range)), promising reproducibility, long-term stability (3.85 % decrease in response over 28 days), and interference immunity. The developed PDMAM-MIP@G electrode was applied to real samples using four branded pepper powder procured from local market and the sensor data was recorded. A convolutional neural network (CNN) driven prediction model has been proposed to predict the piperine concentration. Among the four CNN models tested, the best model, averaged over 50 runs, achieved a mean absolute error (MAE) of 0.268, a mean prediction error of 2.35 %, and a R-squared value of 0.93 on the testing set when compared with reference values obtained from reverse-phase high-performance liquid chromatography (RP-HPLC).

Evaluating the Effectiveness of Cellulose-Based Surfactants in Expandable Graphite Wood Coatings.

This study deals with the design of modern environmentally friendly and non-toxic flame retardants based on expandable graphite 25 K + 180 (EG) modified by cellulose ethers (Lovose TS 20, Tylose MH 300, Klucel H) and nanocellulose (CNC) that are biocompatible with wood and, therefore, are a prerequisite for an effective surfactant for connecting EG to wood. The effectiveness of the formulations and surfactants was verified using a radiant heat source test. The cohesion of the coating to the wood surface and the cohesion of the expanded graphite layer were also assessed. The fire efficiency of the surfactants varied greatly. Still, in combination with EG, they were all able to provide sufficient protection-the total relative mass loss was, in all cases, in the range of 7.38-7.83% (for untreated wood it was 88.67 ± 1.33%), and the maximum relative burning rate decreased tenfold compared to untreated wood, i.e., to 0.04-0.05%·s-1. Good results were achieved using Klucel H + EG and CNC + EG formulations. Compared to Klucel H, CNC provides significantly better cohesion of the expanded layer, but its high price increases the cost of the fireproof coating.

Mechanistic Insights into the Evolution of Graphitic Carbon from Sulfur Containing Polar Aromatic Feedstock.

In the realm of carbon fiber research, a variety of structural configurations is noted, comprising crystalline, noncrystalline, and semicrystalline forms. Recent investigations into this domain have revealed an array of intriguing phases of carbon, among which amorphous graphite is the most notable for its unique mechanical, thermal, and electrical properties that arise from its inherent topological disorders. In this study, we utilized the ReaxFF molecular dynamics (MD) simulations to investigate the carbonization and graphitization processes involved in the production of amorphous graphite from benzothiophene, a sulfur-containing polar aromatic precursor. We developed C/H/S ReaxFF force field parameters to describe the high-temperature chemistry of benzothiophene. Our investigation reveals the reaction mechanisms, providing critical insights into the underlying chemical processes toward the formation of amorphous graphite and the structural characteristics of the end products. The formation of volatile gaseous molecules and their continuous elimination led to the development of noncontinuous layered graphite structures analogous to amorphous graphite consisting of pentagons, hexagons, and heptagons. These findings offer unprecedented insights into the carbonization and graphitization processes of sulfur-containing heavy-end aromatic feedstock. This knowledge lays the groundwork for advancing synthesis methods and developing amorphous graphite materials with specific properties.

Fe3O4 encapsulated in hierarchically porous nitrogen-doped graphitic carbon layers for efficient oxygen reduction reaction: Enhanced intrinsic activity via directional interfacial charge transfer

Constructing efficient electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the commercialization of metal-air batteries. Iron oxide-based catalysts exhibit promising potential for ORR. However, addressing the issue of inferior catalytic performance is essential, and a comprehensive understanding of the catalytic mechanism of iron oxide-based catalysts is also lacking. In this study, we present Fe3O4 nanoparticles encapsulated in N-doped graphitic carbon layers (NGC) hosted by hierarchically porous carbon (Fe3O4@NGC), achieved through a facile dual melt-salt template strategy. The encapsulation of Fe3O4 nanoparticles protects them from corrosion and exfoliation, endowing the catalysts with superior stability. Density functional theory (DFT) calculations discover that the electronic interaction between Fe3O4 nanoparticles and N-doped graphitic carbon layers induces directional interfacial electron transfer, which effectively modulates the surface electronic structure to improve the binding ability to O2, weaken the OO bond, and optimize the adsorption of intermediates, thus boosting the intrinsic activity. DFT unveils that the C atoms nearest to graphitic-N in NGC are active sites. Finally, the synergistic effects of Fe3O4 nanoparticles and NGC result in outstanding ORR performance and superior stability and methanol tolerance of Fe3O4@NGC, with a half-wave potential of 0.89 V, surpassing that of Pt/C by 50 mV. Fe3O4@NGC also shows better performance than Pt/C when used as the air-electrode catalyst in zinc-air battery.

Bottom-up Stripping of Graphene with Controlled Oxidation Behaviors towards Supercapacitors Energy Storage

Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88%. At the current density of 1.0 A g-1, the Go-QAS displayed 225.5 F g-1, and kept about 220.2 F g-1 after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.

Electrolysis destroyed the O-containing bonds of muscovite for the purification of natural flake graphite and its applications

The muscovite is arranged in parallel and tightly combined with the natural graphite layer, which forms a stable structure and impedes the diffusion of hydrofluoric acid in graphite. It requires large quantities of hydrofluoric acid and long diffusion time for effective purification of natural graphite, which leads to increased production costs and significant environmental impact. Therefore, it is necessary to reduce the amount of hydrofluoric acid used and improve purification efficiency. In this work, electrolysis was used to enhance acid leaching purification process and destroy the structure of muscovite to reduce the amount of hydrofluoric acid used. After hydrochloric acid leaching and heat treatment, the purity of natural flake graphite was increased from 95.27 % to 96.60 %, and the remaining impurities were mainly muscovite and quartz. Through electrolysis, the interlayer spacing of muscovite was increased, and the C-O bond between graphite and muscovite was destroyed, making it easier for hydrofluoric acid to enter and react with the muscovite layers. Compared with acid leaching, 99.9 % high-purity graphite was obtained by electrolysis, and the ratio of 40 wt% hydrofluoric acid to natural graphite was decreased from 1.0 mL/g to 0.7 mL/g, reducing the amount of hydrofluoric acid used by 30 %.

An interior damage free approach for nanosecond pulsed laser ablation of single crystal diamond via metal film induced self-maintaining graphitization

When laser ablation was conducted on an uncoated single-crystal diamond (SCD) substrate, interior damage and random ablation were observed. Metal film-induced self-maintaining graphitization (MISG) was proposed as a generic approach to solve this problem. MISG was realized through coating a ∼ 100-nm-thick metal film on an SCD substrate. Experiments involving laser irradiation of metal films, such as Au-, Al-, Ti-, and Pt-coated SCD substrates, revealed that the material removal depths were the same when the output power was the same and that the surface was covered by graphite after laser irradiation. In addition, the laser-induced damage to the upper or lower surface in the case of the uncoated SCD substrate disappeared. A semitransparent model based on Beer-Lambert law and an opaque model based on modified Level-Set method were built to simulate laser irradiation on uncoated and metal–coated SCD substrates. In the case of the uncoated sample, the laser energy was largely absorbed by the areas with high-concentration defects, leading to preferential graphitization. In the case of the metal-coated sample, a graphite layer was thermally induced on the SCD surface via heat transition during the period of laser irradiation of the metal film. Subsequently, the graphite layer was self-maintaining, and the material removal acted like a graphite piston sinking to the interior of the SCD substrate. This study demonstrates the feasibility of MISG as a universal approach for avoiding interior damage during laser ablation of SCD substrates.

Iron-Catalyzed Laser-Induced Graphitization - Multiscale Analysis of the Structural Evolution and Underlying Mechanism.

The transition to sustainable materials and eco-efficient processes in commercial electronics is a driving force in developing green electronics. Iron-catalyzed laser-induced graphitization (IC-LIG) has been demonstrated as a promising approach for rendering biomaterials electrically conductive. To optimize the IC-LIG process and fully exploit its potential for future green electronics, it is crucial to gain deeper insights into its catalyzation mechanism and structural evolution. However, this is challenging due to the rapid nature of the laser-induced graphitization process. Therefore, multiscale preparation techniques, including ultramicrotomy of the cross-sectional transition zone from precursor to fully graphitized IC-LIG electrode, are employed to virtually freeze the IC-LIG process in time. Complementary characterization is performed to generate a 3D model that integrates nanoscale findings within a mesoscopic framework. This enabled tracing the growth and migration behavior of catalytic iron nanoparticles and their role during the catalytic laser-graphitization process. A three-layered arrangement of the IC-LIG electrode is identified including a highly graphitized top layer with an interplanar spacing of 0.343nm. The middle layer contained γ-iron nanoparticles encapsulated in graphitic shells. A comparison with catalyst-free laser graphitization approaches highlights the unique opportunities that IC-LIG offers and discuss potential applications in energy storage devices, catalysts, sensors, and beyond.

Effect of micro-diamond and nano-polycrystalline diamond interfacial microstructure on OLC phase transition

The interfacial microstructure of micro-diamond and nano-polycrystalline diamond (nPCD), as well as their effect on the phase transition of complete structure onion-like carbon (OLC), were investigated using molecular dynamics simulations and experimental methods under high pressure and temperature (HPHT). Introducing micro-diamond disrupted the symmetric equilibrium structure of complete structure OLC, reduced the diamond nucleation process, and formed a coherent interface ((111)CD // (002)Gr), where cubic diamond (111) crystal plane was parallel to graphite (002) crystal plane. This transformed the initial diffusionless phase transition path of complete structure OLC into a low potential path for phase transition along the graphite crystal direction [002] by (111)CD // (002)Gr, thereby reducing the phase transition conditions. Additionally, due to different stacking orders or breakages in the graphite layers of the complete structure OLC, micro-diamond, and nPCD formed four interfacial microstructures containing twin boundaries (TB), cubic diamond, stacking fault (SF), and amorphous grain boundary (aB). Furthermore, under HPHT effects, numerous TBs and SFs were generated inside micro-diamonds as well as at their edges, resulting in a Vickers hardness of 167 GPa for polycrystalline diamond (PCD) composite. This simple yet effective method reduces synthesis conditions for OLC precursors while producing high-performance PCD composites with promising applications.

NaOH-assisted hydrothermal reduction of graphene oxide

The influence of the pH of the reaction medium on the structural characteristics of hydrothermally reduced graphene oxide, synthesized by the Tour method, has been investigated. Varying the pH of the reaction medium within the range of 8.0, 10.0 and 12.0
(adjusted with NaOH) has revealed distinct effects on the morphology and properties of the resulting reduced graphene oxide. At a pH of 8.0 the hydrothermal treatment yielded reduced graphene oxide comprising of two particle fractions with a thickness equivalent to 4-5 graphitic layers each. In contrast, pH of 10.0 resulted in two particle fractions corresponding to 2-3 and 4 layers, respectively, while pH of 12.0 produced a single fraction with a particle thickness of 0.70 nm, encompassing 3 graphitic layers. Increasing the pH led to a decrease in the average lateral size of reduced graphene oxide particles to about 8 nm. All rGOs had micro- and mesopores with a specific surface area up to 226 m2/g, showing a proportional increase in mesopores with increasing pH. Analysis of slit-like micropores revealed a minimum fractal dimension (D = 2.18) at pH = 8.0. The obtained results provide valuable insights into tailoring the structural properties of hydrothermally reduced graphene oxide by controlling the pH of the reaction medium, offering potential applications in various fields, including nanotechnology and materials science.&#xD.

The Effect of a Dual-Layer Coating for High-Capacity Silicon/Graphite Negative Electrodes on the Electrochemical Performance of Lithium-Ion Batteries

Silicon-based electrodes offer a high theoretical capacity and a low cost, making them a promising option for next-generation lithium-ion batteries. However, their practical use is limited due to significant volume changes during charge/discharge cycles, which negatively impact electrochemical performance. This study proposes a practical method to increase silicon content in lithium-ion batteries with minimal changes to the manufacturing process by using dual-layer electrodes (DLEs). These DLEs are fabricated with two slurries containing silicon and graphite as active materials. Notably, the electrode with the silicon as the outermost layer on top of the graphite layer (Si-on-top) demonstrated a superior initial capacity of 935 mAh/g and retained 70% of its capacity (537 mAh/g) after 100 cycles at 0.5 C. In contrast, a single-layered electrode (SLE) with a silicon–graphite mixture retained only 50.3% of its capacity (370 mAh/g) under the same conditions. These findings suggest that DLEs, particularly with the silicon layer located on top, effectively increase silicon content in the negative electrode while remaining compatible with existing manufacturing processes. This approach offers a realistic strategy for enhancing the performance of lithium-ion batteries without significant process modifications.

Intrinsic interlayer shear strength of graphite

Graphite holds significant values in the energy and electronics industries due to its unique properties. As a quintessential example of highly anisotropic materials, the shear strength measures one of its most fundamental mechanical properties. However, the lack of ideal materials and testing methods has led to a wide dispersion in the reported values. To address this issue, we utilized epitaxially grown single-crystal graphite and developed a high-throughput sample preparation method, along with a novel loading technique in this work. The intrinsic shear strength of AB-stacked graphite was determined to be τs = 62 MPa, by excluding the size effect in measurements. The results are further compared to highly oriented pyrolytic graphite specimens processed down to nanoscale thickness, highlighting the adverse impact of twisted single-crystalline interfaces between the graphitic layers. Additionally, we observed a distinctive failure mechanism with continuous and uniform cascade plastic slips across the thickness of graphite samples, which corresponds to an interlayer shear strength approaching τs. The intrinsic shear strength characterized in our work sets an upper limit for the interlayer shear resistance of graphite. The experimental procedure for measuring shear strength can be applied to other van der Waals materials.

Enhanced oxidation resistance and electrochemical performance of PEMFC gas diffusion layer through [EMIM][TFSI] ionic liquid coating

The performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) are critically hindered by the oxidation susceptibility of graphite felt gas diffusion layers (GDLs). This study addresses this challenge by employing a protective coating of 1-Ethyl-3-methylimidazolium Bis(trifluoromethyl sulfonyl)imide ([EMIM][TFSI]) on the GDL through a dip-coating method, followed by thermal curing to ensure uniform distribution and strong adherence. Comprehensive characterization, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier-Transform Infrared Spectroscopy (FTIR), confirmed the homogeneous coating, adhesion, and maintained porosity and gas diffusion properties of the GDL. The coated GDL exhibited a substantial increase in oxidation resistance, resulting in higher hydrophobicity with a contact angle of approximately 131°, compared to 96° for the uncoated GDL. Electrochemical analyses revealed that the [EMIM][TFSI]-coated GDL achieved a current density of 27 mA cm−2 at 0.925 V, surpassing the 19 mA cm−2 of the uncoated GDL at 0.91 V during cyclic voltammetry (CV) analysis. This study is limited by the short-term stability tests and the specific environmental conditions under which the experiments were conducted. Future work will focus on optimizing the coating process for varied environmental conditions and exploring the scalability of this technique for practical applications.

Rapid and Cost-Effective Fabrication and Performance Evaluation of Force-Sensing Resistor Sensors

In this study, we developed a cost-effective and rapid method for fabricating force-sensing resistor (FSR) sensors as an alternative to commercial force sensors. Our aim was to achieve performance characteristics comparable to existing commercial products while significantly reducing costs and fabrication time. We analyzed the material composition of two widely used commercial force sensors: Interlink FSR-402 and Flexiforce A201-1. Based on this analysis, we selected 4B and 9B pencils, which contain high concentrations of graphite, and silicone sealant to replicate these material properties. The fabrication process involved creating piezoresistive sheets by shading A4 copy paper with 4B and 9B pencils to form a uniform layer of graphite. Additionally, we prepared a mixture of 9B pencil lead powder and silicone sealant, ensuring a consistent application on the paper substrate. Measurement results indicated that the force sensor fabricated using a mixture of 9B pencil powder and silicone sealant exhibited electrical and mechanical characteristics closely resembling those of commercial sensors. Load tests revealed that the hand-made sensors provided a proportional voltage output in response to increasing and decreasing loads, similar to commercial FSR sensors. These results suggest that our fabrication method can produce reliable and accurate FSR sensors suitable for various applications, including wearable technology, robotics, and force-sensing interfaces. Overall, this study demonstrates the potential for creating cost-effective and high-performance FSR sensors using readily available materials and simple fabrication techniques.