Activated jute carbon paste screen-printed FTO electrodes for nonenzymatic amperometric determination of nitrite

Integration of Ultrathin Bubble Walls and Electrochemistry: Innovation in Microsensing for Forensic Nitrite Detection and Microscale Metallic Film Deposition

We present a strategy for electrochemical measurements using a durable minute bubble wall with a thickness of 27 μm (D = 1.8 cm) as an innovative electrochemical medium. The composition, thickness, and volume of the tiny bubble film were investigated and estimated using the spectroscopic method and the Beer-Lambert law. A carbon microelectrode (D = 10 μm) was then employed as the working electrode, inserted through the bubble wall to function as the solution interface. First, the potential of this method for microelectrodeposition of metallic Ag and Pd films in a tiny bubble was investigated. Interestingly, microscopic images of the deposited film clearly demonstrated that the bubble thickness determines and confines the electrochemical deposition zone. In other words, innovative template-free microelectrodeposition was achieved. In the second phase of our work, microelectroanalysis of trace levels of nitrite ions was performed within the bubble wall and on a foam-covered hand, between the fingers directly, with a low limit of detection of 28 μM. This technique holds significance in criminal investigations, as the presence of NO2- ions on the hand indicates the potential presence of gunshot residue and aids in identifying suspects. In comparison to current methods, this approach is rapid, simple, cost-effective, and amenable to on-site applications, eliminating the need for sample treatment. Ultimately, the utilization of a bubble wall as a novel electrochemical microreactor can open new ways in microelectrochemical analysis, presenting novel opportunities and applications in the field of electrochemical sensors.

Enhancing electrochemical nitrite sensing with a novel nanocomposite of activated carbon/carbon cloth derived from microbial biofilm

A novel approach was employed to fabricate a biofilm-derived activated carbon (BioAc) electrode on a carbon cloth (Cc) substrate for electrochemical nitrite sensing in water samples. The biofilm/Cc electrode was developed using a bioelectrochemical reactor, featuring a three-electrode system with nutrient media and microbial sources. The resultant biofilm electrode was activated at 450 °C for 2 h to eliminate impurities and enhance porosity. Morphological analysis of the BioAc/Cc electrode revealed a surface characterized by a compact film composed of numerous carbon nanoparticles. X-ray diffraction (XRD) analysis exhibited broad, highly crystalline peaks, enhancing both the electrode surface area and conductivity. Amperometry tests on the modified BioAc/Cc electrodes demonstrated a detection limit of 0.015 μM, a sensitivity of 1946.54 μA mM-1 cm-2, and a linear range spanning 0.35-478.21 μM at neutral pH conditions. Moreover, the electrodes demonstrated good stability with a RSD of 2.25% after 60 days and high reproducibility with an RSD of 1.64%. Real-time results showed 99.2 and 100.1% recovery for tap water and drinking water, respectively, highlighting the potential for commercialization in the future. These findings suggest that the BioAc/Cc electrode holds substantial potential for precise nitrite detection in environmental and wastewater applications.

Detection of Leptin Using Electrocatalyst Mediated Impedimetric Sensing

Obesity is a complex disorder associated with immense health consequences including high risk of cardiovascular diseases, diabetes, and cancer. Abnormality in the thyroid gland, genetics, less physical activity, uptake of excessive diet, and leptin resistance are critical factors in the development of obesity. To determine the treatment strategy, understanding the pathophysiology of obesity is crucial. For instances, leptin resistance mediated obesity defined by the presence of excessive leptin hormone (Lep) in the systemic circulation is very common in diet induced obesity. Therefore, our hypothesis is that quantitative measurement of Lep from blood can help to identify individuals with Lep resistant mediated obesity and thereby guide toward a proper treatment strategy. In this work, we aim to utilize an electrochemical immunosensing platform for diagnosis of obesity by measuring the Lep content in systemic circulation. A porous carbon confined FeNi bimetallic system was synthesized with three different ratios of Fe and Ni ions using high temperature pyrolysis technique. The suitability of the sensor for detecting Lep was studied using both CV and EIS techniques. The limit of detection (LOD) for GCE was recorded as 157.4 fg/mL with a wide linear concentration range of 500 fg/mL to 80 ng/mL, while for SPCE the LOD was 184.9 fg/mL with a linear range of 500 fg/mL to 50 ng/mL. Finally, the feasibility and applicability of the sensor for Lep detection was tested with serum collected from high fat diet induced obese rats. The selectivity, sensitivity, storage, and experimental stability and reproducibility tests showed potential for this biosensor platform as a point-of-care Lep detection device.

Preparation of Highly Stable and Electrochemically Active Three-dimensional Interconnected Graphene Frameworks from Jute Sticks

Over the past few years, the environmentally friendly synthesis of nanomaterials, including graphene using green chemistry, has attracted tremendous attention due to its easy handling, low cost, and biocompatibility. Here we demonstrate a facile and efficient green synthesis route for producing highly stable and electrochemically active three-dimensional interconnected graphene frameworks (3DIGF) from jute sticks. Initially, jute sticks derived three-dimensional amorphous activated carbon nanosheets (3DAACNs) were prepared at low temperatures (i.e., 850 °C) in an inert environment. The resultant 3DAACNs were then heat treated at a high temperature (i.e., 2700 °C) under an inert environment, resulting in 3DIGF. The prepared carbonaceous materials were fully characterized, and various experimental techniques confirmed the preparation of 3DIGF. The prepared 3DIGF shows a highly stable nature in thermal and chemical environments and demonstrates a highly dynamic nature for the electrooxidation of sulfide. This study could be considered a vital contribution towards the economic and simple approach for preparing 3DIGF from biomass.

Date-Leaf Carbon Particles for Green Enhanced Oil Recovery

Green enhanced oil recovery (GEOR) is an environmentally friendly enhanced oil recovery (EOR) process involving the injection of green fluids to improve macroscopic and microscopic sweep efficiencies while boosting tertiary oil production. Carbon nanomaterials such as graphene, carbon nanotube (CNT), and carbon dots have gained interest for their superior ability to increase oil recovery. These particles have been successfully tested in EOR, although they are expensive and do not extend to GEOR. In addition, the application of carbon particles in the GEOR method is not well understood yet, requiring thorough documentation. The goals of this work are to develop carbon nanoparticles from biomass and explore their role in GEOR. The carbon nanoparticles were prepared from date leaves, which are inexpensive biomass, through pyrolysis and ball-milling methods. The synthesized carbon nanomaterials were characterized using the standard process. Three formulations of functionalized and non-functionalized date-leaf carbon nanoparticle (DLCNP) solutions were chosen for core floods based on phase behavior and interfacial tension (IFT) properties to examine their potential for smart water and green chemical flooding. The carboxylated DLCNP was mixed with distilled water in the first formulation to be tested for smart water flood in the sandstone core. After water flooding, this formulation recovered 9% incremental oil of the oil initially in place. In contrast, non-functionalized DLCNP formulated with (the biodegradable) surfactant alkyl polyglycoside and NaCl produced 18% more tertiary oil than the CNT. This work thus provides new green chemical agents and formulations for EOR applications so that oil can be produced more economically and sustainably.

Current Development and Future Perspective on Natural Jute Fibers and Their Biocomposites

The increasing trend of the use of synthetic products may result in an increased level of pollution affecting both the environment and living organisms. Therefore, from the sustainability point of view, natural, renewable and biodegradable materials are urgently needed to replace environmentally harmful synthetic materials. Jute, one of the natural fibers, plays a vital role in developing composite materials that showed potential in a variety of applications such as household, automotive and medical appliances. This paper first reviews the characterization and performance of jute fibers. Subsequently, the main focus is shifted towards research advancements in enhancing physical, mechanical, thermal and tribological properties of the polymeric materials (i.e., synthetic or biobased and thermoplastic or thermoset plastic) reinforced with jute fibers in a variety of forms such as particle, short fiber or woven fabric. It is understood that the physio-mechanical properties of jute-polymer composites largely vary based on the fiber processing and treatment, fiber shape and/or size, fabrication processes, fiber volume fraction, layering sequence within the matrix, interaction of the fiber with the matrix and the matrix materials used. Furthermore, the emerging research on jute fiber, such as nanomaterials from jute, bioplastic packaging, heavy metal absorption, electronics, energy device or medical applications and development of jute fiber composites with 3D printing, is explored. Finally, the key challenges for jute and its derivative products in gaining commercial successes have been highlighted and potential future directions are discussed.

Recent Advancements in Electrochemical Deposition of Metal-Based Electrode Materials for Electrochemical Supercapacitors

The demand for energy storage devices with high energy and power densities has increased tremendously in this rapidly growing world. Conventional capacitors, fuel cells, and lithium-ion batteries have been used as energy storage devices for the long term. However, supercapacitors are one of the most promising energy storage devices because of their high specific capacitance, high power density, and longer cycle life. Recent research has focused on synthesizing transition-metal oxides/hydroxides, carbon materials, and conducting polymers as supercapacitor electrode materials. The performance of supercapacitors can be improved by altering electrolytes, electrode materials, current collectors, experimental temperatures, and film thickness. Thousands of papers on supercapacitors have already been published, reflecting the significance and elucidating how much demanding such energy storage devices for this fast-growing generation. This review aims to illustrate the electrode materials loaded on various conductive substrates by electrochemical deposition employed for supercapacitors to provide broad knowledge on synthetic pathways, which will pave the way for future research. We also discussed the basic parameters involved in supercapacitor studies and the advantages of the electrochemical deposition techniques through literature analysis. Finally, future trends and directions on exploring metals/metal composites toward designing and constructing viable, high-class, and even newly featured flexible energy storage materials, electrodes, and systems are presented.

Preparation of Sulfur-doped Carbon for Supercapacitor Applications: A Review

Electrochemical capacitors, also known as supercapacitors (SCs), have lately played an important role in energy storage and conversion systems due to their specific characteristics such as high strength, durability, and environmental friendliness. A wide range of materials is used as electrodes for SC applications because the electrochemical efficiency is primarily determined by the electrode materials used. Carbonaceous materials with unique surface, chemical, electrochemical, and electronic characteristics have become attractive for energy storage research, but they cannot meet the rising need for high specific energy and specific power. Besides, heteroatom-doped carbon materials have shown pseudocapacitance characteristics and improved specific energy, specific power, and conductivity. This makes them more adaptable in SC application. Among different heteroatom doping of carbon, S-doped carbon has gained considerable attention in SC applications due to its unpaired electrons and easily polarizable nature. S-doped carbon materials-based SCs have demonstrated enhanced surface wettability, improved conductivity, and induced pseudocapacitance effect, thereby delivering improved specific energy and specific power. Many reports on S-doped carbon for SC applications have been published, but there is no specific Review on the preparation of S-doped carbon for SC applications. This Review focuses on recent developments in the field of SC electrodes made from S-doped carbon materials. Herein, the preparation methods and applications of S-doped carbon for SCs were summarized following a brief discussion of different electrochemical characterization techniques of SCs. Finally, the challenges of S-doped carbon materials and their potential prospects were discussed to give crucial insights into the favorable factors for future innovations of SC electrodes. This Review aims to provide insight for further research on the preparation of S-doped carbon for electrochemical energy storage applications.

Recent Advances in Processing and Applications of Heterobimetallic Oxide Thin Films by Aerosol-assisted Chemical Vapor Deposition

The fabrication of smart, efficient, and innovative devices critically needs highly refined thin-film nanomaterials; therefore, facile, scalable, and economical methods of thin films production are highly sought-after for the sustainable growth of the hi-tech industry. The chemical vapor deposition (CVD) technique is widely implemented at the industrial level due to its versatile features. However, common issues with a precursor, such as reduced volatility and thermal stability, restrict the use of CVD to produce novel and unique materials. A modified CVD approach, named aerosol-assisted CVD (AACVD), has been the center of attention due to its remarkable tendency to fabricate uniform, homogenous, and distinct nano-architecture thin films in an uncomplicated and straightforward manner. Above all, AACVD can utilize any custom-made or commercially available precursors, which can be transformed into a transparent solution in a common organic solvent; thus, a vast array of compounds can be used for the formation of nanomaterial thin films. This review article highlights the importance of AACVD in fabricating heterobimetallic oxide thin films and their potential in making energy production (e. g., photoelectrochemical water splitting), energy storage (e. g., supercapacitors), and environmental protection (e. g., electrochemical sensors) devices. A heterobimetallic oxide system involves two metallic species either in a composite, solid solution, or metal-doped metal oxides. Moreover, the AACVD tunable parameters, such as temperature, deposition time, and precursor, which drastically affect thin films microstructure and their performance in device applications, are also discussed. Lastly, the key challenges and issues of scaling up AACVD to the industrial level and processing for emerging functional materials are also highlighted.

Preparation, Characterization, and Evaluation of the Anticorrosion Performance of Submicron/Nanocarbon from Jute Sticks

Jute stick, one of the most commonly and abundantly available agricultural waste product, was converted to a value-added submicron/nano jute carbon by using pyrolysis and high-energy ball milling techniques. The submicron/nano jute carbon was characterized using FE-SEM, TEM, EDS, XRD, XPS and Raman spectroscopy. The anticorrosive performance of the submicron/nano jute carbon was investigated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and salt spray techniques, on mild steel plates coated with a mixture of epoxy resin and the submicron/nano jute carbon. The electrochemical impedance of the steel coated with the composite coating was two orders of magnitudes higher than that of the specimen coated with neat epoxy. Consequently, the corrosion rate of specimens coated with composite coating was 13-20 times higher than that of steel coated with neat epoxy coating. The salt spray results also indicate an improvement in the corrosion resistance performance of the composite coating compared to the neat epoxy. The uniform distribution of the submicron/nano jute carbon particles in the epoxy resin improved the denseness of the composite coating by acting as a barrier against the diffusion of chloride, moisture, and oxygen, thus, improving the corrosion resistance of the developed coating.

Graphene and Carbon Nanotube-based Electrochemical Sensing Platforms for Dopamine

Dopamine (DA) is an important neurotransmitter, which is created and released from the central nervous system. It plays a crucial role in human activities, like cognition, emotions, and response to anything. Maladjustment of DA in human blood serum results in different neural diseases, like Parkinson's and Schizophrenia. Consequently, researchers have started working on DA detection in blood serum, which is undoubtedly a hot research area. Electrochemical sensing techniques are more promising to detect DA in real samples. However, utilizing conventional electrodes for selective determination of DA encounters numerous problems due to the coexistence of other materials, such as uric acid and ascorbic acid, which have an oxidation potential close to DA. To overcome such problems, researchers have put their focus on the modification of bare electrodes. The aim of this review is to present recent advances in modifications of most used bare electrodes with carbonaceous materials, especially graphene, its derivatives, and carbon nanotubes, for electrochemical detection of DA. A brief discussion about the mechanistic phenomena at the electrode interface has also been included in this review.

Present Status and Future Prospects of Jute in Nanotechnology: A Review

Nanotechnology has transformed the world with its diverse applications, ranging from industrial developments to impacting our daily lives. It has multiple applications throughout financial sectors and enables the development of facilitating scientific endeavors with extensive commercial potentials. Nanomaterials, especially the ones which have shown biomedical and other health-related properties, have added new dimensions to the field of nanotechnology. Recently, the use of bioresources in nanotechnology has gained significant attention from the scientific community due to its 100 % eco-friendly features, availability, and low costs. In this context, jute offers a considerable potential. Globally, its plant produces the second most common natural cellulose fibers and a large amount of jute sticks as a byproduct. The main chemical compositions of jute fibers and sticks, which have a trace amount of ash content, are cellulose, hemicellulose, and lignin. This makes jute as an ideal source of pure nanocellulose, nano-lignin, and nanocarbon preparation. It has also been used as a source in the evolution of nanomaterials used in various applications. In addition, hemicellulose and lignin, which are extractable from jute fibers and sticks, could be utilized as a reductant/stabilizer for preparing other nanomaterials. This review highlights the status and prospects of jute in nanotechnology. Different research areas in which jute can be applied, such as in nanocellulose preparation, as scaffolds for other nanomaterials, catalysis, carbon preparation, life sciences, coatings, polymers, energy storage, drug delivery, fertilizer delivery, electrochemistry, reductant, and stabilizer for synthesizing other nanomaterials, petroleum industry, paper industry, polymeric nanocomposites, sensors, coatings, and electronics, have been summarized in detail. We hope that these prospects will serve as a precursor of jute-based nanotechnology research in the future.

Physico-chemical properties and toxicological effects on plant and algal models of carbon nanosheets from a nettle fibre clone

Carbon nanosheets are two-dimensional nanostructured materials that have applications as energy storage devices, electrochemical sensors, sample supports, filtration membranes, thanks to their high porosity and surface area. Here, for the first time, carbon nanosheets have been prepared from the stems and leaves of a nettle fibre clone, by using a cheap and straight-forward procedure that can be easily scaled up. The nanomaterial shows interesting physical parameters, namely interconnectivity of pores, graphitization, surface area and pore width. These characteristics are similar to those described for the nanomaterials obtained from other fibre crops. However, the advantage of nettle over other plants is its fast growth and easy propagation of homogeneous material using stem cuttings. This last aspect guarantees homogeneity of the starting raw material, a feature that is sought-after to get a nanomaterial with homogeneous and reproducible properties. To evaluate the potential toxic effects if released in the environment, an assessment of the impact on plant reproduction performance and microalgal growth has been carried out by using tobacco pollen cells and the green microalga Pseudokirchneriella subcapitata. No inhibitory effects on pollen germination are recorded, while algal growth inhibition is observed at higher concentrations of leaf carbon nanosheets with lower graphitization degree.

A highly sensitive poly(chrysoidine G)-gold nanoparticle composite based nitrite sensor for food safety applications

This work demonstrated the development of conducting poly(chrysoidine G) (PCG)-gold nanoparticle (AuNP)-modified fluorine-doped tin oxide (F : SnO₂, FTO) film-coated glass electrodes for the sensitive electrochemical detection of nitrite (NO₂^-). The homogeneously distributed PCG nanoparticle layer was deposited onto the FTO electrode by cyclic voltammetry sweeping. AuNPs were then anchored onto the PCG/FTO electrode by the chemical reduction of pre-adsorbed Au³⁺ ions. The as-prepared AuNP/PCG/FTO electrode exhibited excellent electrocatalytic activity for the oxidation of NO₂^- with high sensitivity (approximately 0.63 μA cm^-2μM^-1) and a low limit of detection (0.095 μM), which is relevant within the normal concentration range of NO₂^- in human bodily fluids. The AuNP/PCG/FTO sensor showed sufficient reproducibility, repeatability, low interference, and strong recovery for NO₂^- detection in food samples. These results indicate that the AuNP/PCG nanocomposites have immense potential for the electrochemical detection of other biologically important compounds.

Metal Nanoparticles for Electrochemical Sensing: Progress and Challenges in the Clinical Transition of Point-of-Care Testing

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) have been discussed in detail. Additionally, the novel coronavirus (2019-nCoV) ECBs have been briefly discussed. Beyond that, the limitations and challenges that ECBs face in clinical applications are examined and possible pathways for overcoming these limitations are discussed.

Controlled-Potential-Based Electrochemical Sulfide Sensors: A Review

Due to their potential applications in industry and potent toxicity to the environment, sulfides and their detection have attracted the attention of researchers. To date, a large number of controlled-potential techniques for electrochemical sulfide sensors have been developed, thanks to their simplicity, reasonable limit of detection (LOD), and good selectivity. Different researchers have applied different strategies for developing selective and sensitive sulfide sensors. However, there has been no systematic review on controlled-potential techniques for sulfide sensing. In light of this absence, the main aim of this review article is to summarize various strategies for detecting sulfide in different media. The efficiencies of the developed sulfide sensors for detecting sulfide in its various forms are determined, and the essential parameters, including sensing strategies, working electrodes, detection media, pH, LOD, sensitivity, and linear detection range, are emphasized in particular. Future research in this area is also recommended. It is expected that this review will act as a basis for further research on the fabrication of sulfide sensors for practical applications.

Preparation and Utilization of Jute-Derived Carbon: A Short Review

This article summarizes the preparation and applications of carbon derived from jute sticks and fibers that are low-cost, widely available, renewable, and environmentally friendly. Both the fibers and sticks are considered ideal candidates of carbon preparation because they are composed of cellulose, hemicelluloses, and lignin, and contain negligible ash content. Various carbon preparation methods including simple pyrolysis, pyrolysis with chemical and physical activations are discussed. The impacts of several parameters including types of activating agents, impregnation ratio, and temperature on their morphology, surface area, pore size, crystallinity, and surface functional groups are also emphasized. Various treatments to endow functionalization for increasing the practical applicability, such as chemical, physical, and physico-chemical methods, are discussed. In addition, applications of jute-derived carbon in various practical areas, including energy storage, water treatment, and sensors, are also highlighted in this report. Due to the porous fine structure and a large specific surface area, the jute-derived carbon could be considered as a powerful candidate material for various industrial applications. Finally, possible future prospects of jute-derived carbon for various applications are pointed out.

Computational Approach to Understanding the Electrocatalytic Reaction Mechanism for the Process of Electrochemical Oxidation of Nitrite at a Ni-Co-Based Heterometallo-Supramolecular Polymer

Here, we report a semiempirical quantum chemistry computational approach to understanding the electrocatalytic reaction mechanism (ERM) of a metallic supramolecular polymer (SMP) with nitrite through UV/vis spectral simulations of SMP with different metal oxidation states before and after interactions with nitrite. In one of our recent works, by analyzing the electrochemical experimental data, we showed that computational cyclic voltammetry simulation (CCVS) can be used to predict the possible ERM of heterometallo-SMP (HMSMP) during electrochemical oxidation of nitrite (Islam T.ACS Appl. Polym. Mater.2020, 2( (2), ), 273-284). However, CCVS cannot predict how the ERM happens at the molecular level. Thus, in this work, we simulated the interactions between the repeating unit (RU) of the HMSMP polyNiCo and nitrite to understand how the oxidation process took place at the molecular level. The RU for studying the ERM was confirmed through comparing the simulated UV/vis and IR spectra with the experimental spectra. Then, the simulations between the RU of the polyNiCo and various species of nitrite were done for gaining insights into the ERM. The simulations revealed that the first electron transfer (ET) occurred through coordination of NO₂ ^- with either of the metal centers during the two-electron-transfer oxidation of nitrite, while the second ET followed a ligand-ligand charge transfer (LLCT) and metal-ligand charge transfer (MLCT) pathway between the NO₂ species and the RU. This ET pathway has been proposed by analyzing the transition states (TSs), simulated UV/vis spectra, energy of the optimized systems, and highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO) interactions from the simulations between the RU and nitrite species.

Facile synthesis and characterization of erbium oxide (Er2O3) nanospheres embellished on reduced graphene oxide nanomatrix for trace-level detection of a hazardous pollutant causing Methemoglobinaemia

The nanomaterials have received enormous attention in the catalysis applications. Particularly, we have focused on the fabrication of nanocomposite for an electrochemical sensor with improved electrocatalytic performance. Herein, a rapid and sensitive electrochemical detection of nitrite is essential for assessing the risks facing ecosystems in environment. We report a simple and robust ultrasonic-assisted synthetical route via prepared Er₂O₃ nanoparticles decorated reduced graphene oxide nanocomposite (Er₂O₃ NPs@RGO) modified electrode for nitrite detection. The composition and morphological formation were characterized by XRD, XPS, FESEM, and HRTEM. The amperometric (i-t) and cyclic voltammetry were exhibits tremendous electrocatalytic capability and superior performance toward nitrite oxidation. A sensitive and reproducible amperometric nitrite sensor was fabricated which able to detect trace concentration as 3.69 nM and excellent sensitivity (24.17 µA µM^-1 cm^-2). The method worked well even in cured meat and water samples and the results has indicates the reliability of the method in real-time analysis.