Electrochemical Applications Research Articles

Ligand-Insertion Strategy for Constructing 2D Conjugated Metal-Organic Framework with Large Pore Size for Electrochemical Analytics.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have shown great promise in various electrochemical applications due to their intrinsic electrical conductivity. A large pore aperture is a favorable feature of this type of material because it facilitates the mass transport of chemical species and electrolytes. In this work, we propose a ligand insertion strategy in which a linear ligand is inserted into the linkage between multitopic ligands, extending the metal ion into a linear unit of -M-ligand-M-, for the construction of 2D c-MOFs with large pore apertures, utilizing only small ligands. As a proof-of-concept trial of this strategy, a 2D c-MOF with mesopores of 3.2 nm was synthesized using commercially available ligands hexahydrotriphenylene and 2,5-dihydroxybenzoquinone. The facilitation of the diffusion of redox species by the large pore size of this MOF was demonstrated through a series of probes. With this feature, it showed superior performance in the electrochemical analysis of a variety of biological species.

Interfacial Electronic Interactions Promoted Activation for Nitrate Electroreduction to Ammonia over Ag‐Modified Co3O4

AbstractElectrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts.

Microstructure modification strategies of coal-derived carbon materials for electrochemical energy storage applications

Microstructure modification strategies of coal-derived carbon materials for electrochemical energy storage applications

Integration and Characterization of Synthetic Biodegradable Polymer (PVA) with Graphite Oxide (GO) for Performance Assessment in Sustainable Electrochemical Devices

AbstractIn recent years, the demand for sustainable materials in electrochemical devices has driven the exploration of innovative composites. This study focuses on the integration and characterization of synthetic biodegradable polymer polyvinyl alcohol (PVA) with graphite oxide (GO) to evaluate their performance in sustainable electrochemical applications. PVA, known for its biodegradability and biocompatibility, was combined with GO to leverage its excellent electrical conductivity and large surface area. Microbial fuel cells (MFCs) represent a promising electrochemical biosynthesis technology that harnesses the enzymatic activities using microbes to produce energy from organic substrates. This renewable energy approach relies on the synergistic interaction between electrochemically active bacteria and electrode materials to facilitate electron transfer and power generation. Applications of MFCs range from wastewater treatment to sustainable power generation in remote or resource-limited settings. This study explores recent advances in MFC technology, challenges in scaling up for practical applications, and prospects for integrating MFCs into renewable energy strategies. The nano composite membrane was evaluated for structural, morphological, crystalline, and thermal properties by using Fourier Transform Infrared Spectroscopic (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and UV- visible spectroscopy. Additionally, the biodegradability of the composite was assessed, confirming that it maintains its environmental benefits while offering improved performance for potential applications in sustainable energy storage and conversion devices. This work provides a promising avenue for the development of eco-friendly electrochemical devices with optimized performance characteristics.

Non-enzymatic g-C3N4 supported CuO derived-biochar based electrochemical sensors for trace level detection of malathion

Malathion (MALA), a widely used insecticide, even at trace levels exhibits deleterious effects towards respiratory tracts, and nervous system, necessitating its detection. Herein, we have offered non-enzymatic trace level monitoring of MALA using g-C3N4 supported CuO-derived biochar. The present B-CuO/g-C3N4 based electrochemical sensor is synthesized using hydrothermal approach followed by calcination at high temperature. The result unveiled the strong <pi-pi> interactions, high charge separation efficiency, significant porosity leading to excellent electrochemically active surface area 9.88 × 10−5 cm2 with least charge transfer resistance (RCT) value of 35.2 K Ω. The B-CuO/g-C3N4 based nanocomposite offered excellent complex formation ability with MALA and square wave anodic stripping voltametric method (SWASV) generates an enhanced electrochemical signal due to oxidation of MALA. Following all necessary optimizations, the sensor was capable to exhibit limit of detection (LOD) value of 1.2 pg mL−1 with R2 = 0.968. The modified biosensor offered its potential towards detection of MALA in apple and tomato samples with a recovery ranging from 87.64 to 120.59%. This novel B-CuO/g-C3N4 ternary nanocomposite provides non-enzymatic detection of MALA having excellent electrochemical properties and hence opens new pathways for exploring the use of biochar in other electrochemical applications.

A novel technique of dual modified acid-washed layered double hydroxides-biochar for adsorption and as potential catalysts for electrochemical applications

The enhanced concentration of nitrate ions in wastewater delivered from industries has led to consequential environmental issues and severe health problems for humanity. Considering the advantages to the environment and being cost-effective, adsorption techniques based on biochar materials have appeared as a remarkable strategy to adsorb nitrate. Although the porous nature of the biochar materials aids in adsorption, the stability is a significant hindrance, thus limiting nitrate adsorption. Thus, in an effort to tackle this difficulty, layered double hydroxide (LDH) modified with cationic surfactant rice husk biochar is utilized to enhance the stability and the performance of nitrate adsorption. In the current research, pristine biochar (Pure-BC), surfactant-modified biochar (BC-S), varying concentrations of iron and magnesium-modified LDH with surfactant biochar materials (FM-SL, MF-SL) were synthesized, and batch experiments were conducted in order to explore their performance of nitrate adsorption. The acid-washed biochar exhibited novel rapid adsorption within a period of 10 min and a maximum adsorption capacity of 72 mg/g at neutral pH, whose mechanism was based on both physical and chemical adsorption. Further, the pristine and modified biochar materials were analyzed for their electrochemical behavior in order to explore their chemical reactivity and electron transfer kinetics, with an overpotential value of 67 mV. Thus, the prepared biochar materials, being inexpensive, exhibit potential adsorbents for the adsorption of nitrate from industrial sewage waters and display better electrochemical characteristics.

Stainless Steel Mesh in Electrochemistry: Comprehensive Applications and Future Prospects.

Stainless steel mesh (SSM) has emerged as a cornerstone in electrochemical applications owing to its exemplary versatility, electrical conductivity, mechanical robustness, and corrosion resistance. This state-of-the-art review delves into the diverse roles of SSM across a spectrum of electrochemical domains, including energy conversion and storage devices, water treatment technologies, electrochemical sensors, and catalysis. We meticulously explore its deployment in supercapacitors, batteries, and fuel cells, highlighting its utility as a current collector, electrode, and separator. The review further discusses the critical significance of SSM in water treatment processes, emphasizing its efficacy in supporting membranes and facilitating electrocoagulation, as well as its novel uses in electrochemical sensing and catalysis, which include electrosynthesis and bioelectrochemistry. Each section delineates the recent advancements, identifies the inherent challenges, and suggests future directions for leveraging SSM in electrochemical technologies. This comprehensive review showcases the current state of knowledge and articulates the novel integration of SSM with emerging materials and technologies, thereby establishing a new paradigm for sustainable and efficient electrochemical applications. Through critical analysis and insightful recommendations, this review positions itself as a seminal contribution, paving the way for researchers and practitioners to harness the full potential of SSM in advancing the electrochemistry frontiers.

Bioinspired synthesis of calcium magnesium aluminate nanoparticles using aloe vera extract: A promising material for electrochemical sensors, antibacterial and environmental remediation applications

Aloe vera (Aloe barbadensis miller) leaf extract was used in green fuel-assisted microwave synthesis to prepare Calcium Magnesium Aluminate (CMA). The synthesized CMA was characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), Scanning electron microscope (SEM), Energy dispersion spectrometer (EDAX), and Transmission Electron Microscopy (TEM) analyses. X-ray diffraction confirmed the formation of Ca2Mg2Al28O46. The UV–Vis diffuse reflectance (DRS) technique was employed to investigate its absorbance spectrum, and the band gap of CMA was found to be 4.9 eV. The CMA nanoparticles were used to design a sensing electrode for creatinine, enabling the determination of its concentration in human samples and heavy metals. Acid Orange-88 dye was degraded using CMA nanoparticles as a photocatalyst under UV irradiation. After dye degradation, treated water was used to grow Vigna radiata plants to test their suitability for seedling growth. This report demonstrates that CMA photocatalysts are alternatives to semiconductor photocatalysts for the degradation of Acid Orange-88 dye under UV illumination. Escherichia coli (E. coli), Staphylococcus species, and Pseudomonas species were used as model organisms to assess the antibacterial activity of CMA NPs through a green route.

Cobalt-doped graphitic carbon nitride: A multifunctional material for humidity sensing, electrochemical water splitting and environmental remediation applications

Graphitic carbon nitride (g-C3N4) has emerged as a promising eco-friendly material for catalysis and sensing applications due to their unique properties. However, limitations like low specific surface area, insufficient light absorption, and poor conductivity hinder their broader usability. Elemental doping has been established as an effective approach to modify the electronic structure and bandgap of g-C3N4 thus significantly expanding its light-responsive range for enhanced charge separation. This work reports on the fabrication of cost-effective and stable g-C3N4 and cobalt-doped g-C3N4 (Co@g-C3N4) via a simple one-step calcination process. The humidity sensing performance of both g-C3N4 and Co@g-C3N4 was evaluated across a broad humidity range (7 % - 94 % RH) at various testing frequencies. The results demonstrated good reversibility with Co@g-C3N4 exhibiting superior performance compared to pristine g-C3N4. Furthermore, the synthesized materials were assessed for their suitability as photoelectrochemical water splitting catalysts for hydrogen production, representing a step towards energy-efficient fuel cells. Notably, Co@g-C3N4 displayed enhanced performance with a lower onset potential (420 mV) and a lower Tafel slope (65.4 mV dec-1) for the hydrogen evolution reaction (HER) compared to undoped counterparts. Additionally, Co@g-C3N4 nanorods exhibited remarkable performance for the oxygen evolution reaction (OER), showcasing a lower onset potential (1.505 V) and a considerably low overpotential (270 mV), surpassing numerous reported electrocatalysts and even rivaling precious-metal-based ones. Finally, enhanced photocatalytic activities for organic dyes degradation were recorded for the mentioned materials. Therefore, g-C3N4 and related materials have great potential for their industrial electrochemcial applications.

Development and analysis of novel Sm doped LaSiO for photocatalytic degradation and electrochemical sensing of heavy metals

This study explores the synthesis of La10Si6O27:Sm3+ nanoparticles (LSNP) with varying samarium (Sm3+) concentrations (0–8 mol%) using eco-friendly solution combustion method with urea as a fuel. Using powder X-ray diffraction (PXRD), we determined that the nanoparticles typically measure between 15 and 17 nm and display a spherical morphology. These rare earth (RE)-doped nanoparticles were employed as a novel photocatalyst for the degradation of malachite green (MG) dye, exhibit unprecedented photocatalytic efficiency. The release of OH radicals during the degradation process was found to vary with the chemical structure and concentration of the photocatalyst, with the 6 mol% LSNP formulation showing a significant advancement under both UV and sunlight. Electrochemical assessments revealed that these nanoparticles exhibit excellent cyclic stability and robust performance. Notably, the specific capacitance of the nanoparticles increased with the samarium concentration, reaching a peak of 261.3 F/g in 0.1 M HCl. Furthermore, graphite-modified electrodes incorporating these nanoparticles showed significant potential as sensitive materials for detecting mercury and lead in concentrations as low as 1–6 mM, underscoring the versatility and functional adaptability of the synthesized nanoparticles in environmental and electrochemical applications. The prepared La10Si6O27:Sm3+ nanoparticles The nanoparticles demonstrated an optimal photocatalytic efficiency of 95.5 % under UV light and 88.15 % under sunlight at 6 mol% Sm3+ doping. Additionally, a peak specific capacitance of 261.3 F/g was achieved in 0.1 M HCl.

Fe-doped phosphide nanosheet array derived from prussian blue analogues for high-efficient electrocatalytic water splitting

Doping heterogeneous atoms can modulate electronic structure, which matters for creating efficient bifunctional electrocatalysts in realizing conversion of hydrogen and electricity. This study demonstrates that Fe-doped Ni5P4 nanosheet arrays on nickel foam (Fe–Ni5P4/NF) using Prussian blue analogues as precursors are successfully synthesized by straightforward hydrothermal reactions and phosphating. Fe–Ni5P4/NF exhibits great efficiency in creating hydrogen from water under alkaline conditions. The Fe–Ni5P4/NF dual electrode just need a minimal cell voltage of 1.54 V at 10 mA cm−2 and maintain operational stability for a minimum of 50 h, demonstrating outstanding bifunctional properties. The introduction of Fe modifies the electronic configuration for Ni5P4, substantially boosting the activity of the electrocatalyst. This study offers a framework for designing splendid bifunctional electrocatalysts through synergistic doping strategies in electrochemical applications.

Upcycling linear low-density polyethylene waste to turbostratic graphene for high mass loading supercapacitors

Linear low-density polyethylene (LLDPE) waste is difficult to upcycle into more valuable carbon materials because it tends to completely decompose into small molecules during thermal processing. In this work, LLDPE is upcycled into a high quality turbostratic graphene using a pre-treatment step to oxidatively crosslink the polymer with the assistance of solid additives (KCl and K2CO3) that improve crosslinking by increasing the effective surface area of the polymer melt during processing. After this pretreatment step, the crosslinked polymer could then be carbonized and catalytically graphenized between 400–950 °C without decomposition of the polymer feedstock. The LLDPE derived graphene (LLDPE-G) obtained from this process has a Brunauer–Emmett–Teller (BET) specific surface area, up to 1800 m2 g−1 and average Raman ID/IG and I2D/IG ratios of 0.85 and 0.57, respectively, indicating high quality graphene. When used as an electrode material in symmetric supercapacitors, LLDPE-G possesses a specific capacitance up to 175 Fg−1 at a mass loading of 20 mgcm−2, which is two times the commercial requirement, yielding an areal capacitance of 3.5 Fcm−2. Moreover, LLDPE-G exhibits exceptional cycling stability with a capacitance retention of 95.8 % after 100,000 cycles at a current density of 4.0 Ag−1. Additionally, the KCl and K2CO3 solids are recycled and reused over 3 complete reaction cycles to make new LLDPE-G with the material quality and electrocapacitive performance retained and verified after each cycle. Our approach creates new opportunities for upcycling waste LLDPE and other varieties of polyethylene into a higher value graphene used for electrochemical energy storage applications.

Structural, electrical, and transport properties of a PVB: NH4Br complexed solid polymer electrolyte films for electrochemical cell applications

ABSTRACT Polymer electrolytes are a key development in advancing battery technology, enabling more efficient energy storage. This study focused on developing a solid-state polymer electrolyte film by doping NH4Br with Polyvinyl Butyral (PVB) using a solution-cast method. X-ray diffraction (XRD) was employed to evaluate the amorphousness and crystallinity of the films, while Fourier Transform Infrared Spectroscopy (FTIR) confirmed complex formation between the salt and polymer. The glass transition temperature (Tg) of the electrolyte film was estimated using Differential Scanning Calorimetry (DSC). Ionic conductivity was measured through AC impedance spectroscopy, revealing that the PVB-NH4Br electrolyte doped with 30 wt% NH4Br at 30 °C had an ionic conductivity of 1.47 × 10−7 S cm−1. This conductivity followed an Arrhenius relationship, where conductivity increased with temperature. Dielectric studies showed that at low frequencies, the dielectric constant and loss were higher, while both decreased at higher frequencies. DC Wagner’s polarization technique verified that ion transport was the dominant conduction mechanism. Discharge testing of the electrolyte film using a Swagelok cell showed an open-circuit voltage (OCV) of 1.2 V and a short-circuit current (SCC) of 0.42 mA, indicating promising performance for battery applications.

Porous Silicon-Supported Catalytic Materials for Energy Conversion and Storage.

Porous silicon (Si) has a tetrahedral structure similar to that of sp3- hybridized carbon atoms in a typical diamond structure, which affords it unique chemical and physical properties including an adjustable intrinsic bandgap, a high-speed carrier transfer efficiency. It has shown great potential in photocatalysis, rechargeable batteries, solar cells, detectors, and electrocatalysis. This review introduces various porous Si-supported electrocatalysts and analyzes the reasons why porous Si is used as a new carrier/active sites from the perspectives of its molecular structure, electronic properties, synthesis methods, etc. The electrochemical applications of porous Si-based electrocatalysts in energy conversion reactions such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and total water decomposition together with lithium-ion batteries (LIBs) and supercapacitors in energy storage are summarized. The challenges and future research directions for porous Si are also discussed. This review aims to deepen the understanding of porous Si and promote the development and applications of this new type of Si material.

Enhanced stability in Co0.8Ni0.2/NDMCS catalysts: Carbon nitride encapsulation for robust hydrogen generation

Catalytic hydrolysis of NaBH4 is a promising method for "on-demand" hydrogen generation, with cobalt catalysts playing a key role due to their high hydrogen generation rates. However, rapid cobalt dissolution and poor recycling hinder stable hydrogen production. This study presents a dual-mode stabilization technique using carbon nitride encapsulation to address these challenges. Co0.8Ni0.2 alloy nanoparticles (NPs) are confined within N-doped mesoporous carbon spheres (NDMCS) and encapsulated with a carbon nitride shell (∼ 5 nm thick). XPS results reveal strong non-classical metal-support interaction, increasing activation energy from 38.82 to 44.6 kJ mol−1, which controls cobalt's reactivity, leading to excellent recycling efficiency (90 % retention of initial rate, no change in particle size) in high-concentration reactants (2 %NaBH4 + 2 %NaOH). The retention rate drops to 26.8 % without this stabilization due to rapid metal dissolution. This stability of Co0.8Ni0.2 alloy in alkaline conditions has significant practical implications for hydrogen generation and other electrochemical applications.

Development of a processing route for the fabrication of thin hierarchically porous copper self-standing structure using direct ink writing and sintering for electrochemical energy storage application

Development of a processing route for the fabrication of thin hierarchically porous copper self-standing structure using direct ink writing and sintering for electrochemical energy storage application

Aminotriazine derived N-doped mesoporous carbon with a tunable nitrogen content and their improved oxygen reduction reaction performance.

The electrocatalytic activity of carbon materials is highly dependent on the controlled modulation of their composition and porosity. Herein, mesoporous N-doped carbon with different amounts of nitrogen was synthesized through a unique strategy of using a high nitrogen containing CN precursor, 3-amino 1,2,4 triazine (3-ATZ) which is generally used for the preparation of carbon nitrides, integrated with the combination of a templating method and high temperature treatment. The nitrogen content and the graphitisation of the prepared materials were finely tuned with the simple adjustment of the carbonisation temperature (800-1100 °C). The optimised sample as an electrocatalyst for oxygen reduction reaction (ORR) exhibited an onset potential of 0.87 V vs. RHE with a current density of 5.1 mA cm-2 and a high kinetic current density (Jk) of 33.1 mA cm-2 at 0.55 V vs. RHE. The characterisation results of the prepared materials indicated that pyridinic and graphitic nitrogen in the carbon framework promoted ORR activity with improved four-electron selectivity and excellent methanol tolerance and stability. DFT calculations demonstrated that the structural and planar defects in the N-doped carbon regulated the surface electronic properties of the electrocatalyst, leading to a reduction in the energy barrier for the ORR activity. This strategy has the potential to unlock a platform for designing a series of catalysts for electrochemical applications.

Electronic Structure Regulated Carbon-Based Single-Atom Catalysts for Highly Efficient and Stable Electrocatalysis.

Single-atom-catalysts (SACs) with atomically dispersed sites on carbon substrates have attained great advancements in electrocatalysis regarding maximum atomic utilization, unique chemical properties, and high catalytic performance. Precisely regulating the electronic structure of single-atom sites offers a rational strategy to optimize reaction processes associated with the activation of reactive intermediates with enhanced electrocatalytic activities of SACs. Although several approaches are proposed in terms of charge transfer, band structure, orbital occupancy, and the spin state, the principles for how electronic structure controls the intrinsic electrocatalytic activity of SACs have not been sufficiently investigated. Herein, strategies for regulating the electronic structure of carbon-based SACs are first summarized, including nonmetal heteroatom doping, coordination number regulating, defect engineering, strain designing, and dual-metal-sites scheming. Second, the impacts of electronic structure on the activation behaviors of reactive intermediates and the electrocatalytic activities of water splitting, oxygen reduction reaction, and CO2/N2 electroreduction reactions are thoroughly discussed. The electronic structure-performance relationships are meticulously understood by combining key characterization techniques with density functional theory (DFT)calculations. Finally, a conclusion of this paper and insights into the challenges and future prospects in this field are proposed. This review highlights the understanding of electronic structure-correlated electrocatalytic activity for SACs and guides their progress in electrochemical applications.

Static Subspace Approximation for Random Phase Approximation Correlation Energies: Implementation and Performance.

Developing theoretical understanding of complex reactions and processes at interfaces requires using methods that go beyond semilocal density functional theory to accurately describe the interactions between solvent, reactants and substrates. Methods based on many-body perturbation theory, such as the random phase approximation (RPA), have previously been limited due to their computational complexity. However, this is now a surmountable barrier due to the advances in computational power available, in particular through modern GPU-based supercomputers. In this work, we describe the implementation of RPA calculations within BerkeleyGW and show its favorable computational performance on large complex systems relevant for catalysis and electrochemistry applications. Our implementation builds off of the static subspace approximation which, by employing a compressed representation of the frequency dependent polarizability, enables the evaluation of the RPA correlation energy with significant acceleration and systematically controllable accuracy. We find that the computational cost of calculating the RPA correlation energy scales only linearly with system size for systems containing up to 50 thousand bands, and is expected to scale quadratically thereafter. We also show excellent strong scaling results across several supercomputers, demonstrating the performance and portability of this implementation.

Decoupling Charge Carrier Electroreduction and Enzymatic CO2 Conversion to Formate Using a Dual-Cell Flow Reactor System.

With an efficient atom economy, low activation energy, and valuable applications for fuel cells and hydrogen storage, formic acid (FA) is a useful fuel product to convert CO2 and reduce emissions. Although metal catalysts are typically used for this conversion, unwanted side reactions remain a concern, particularly when products are attempted to be recovered long-term. In this study, an enzymatic catalyst is used to enable the selective conversion of CO2 to FA, as a formate ion. A dual-cell flow reactor system is used to first reduce a charge mediator electrochemically (reduction cell), which then activates a catalyst to selectively convert CO2 to formate (production cell). This approach minimizes enzyme degradation by avoiding direct contact with increased voltages and improves the quantity of formate produced. The system produced 25 mM of formate and reached over 50% Coulombic efficiency. The larger volume of this dual-cell system increases the quantity of formate produced beyond that of a batch cell. Additional design configurations are employed, including a pH control pump to maintain catalyst activity and a packed bed reactor to improve contact of the charge carrier with the catalyst. Both configurations retained higher production and efficiency long-term (∼168 h). The results highlight the challenges of developing a system where many parameters play a role in optimizing performance. Nevertheless, the ability of the system to produce formate from CO2 demonstrates the potential to improve upon this configuration for a variety of electrochemical CO2 conversion applications.