Plastic Electrodes Research Articles

Simultaneous Production of Biogas and Electricity from Anaerobic Digestion of Pine Needles: Sustainable Energy and Waste Management.

Power scarcity and pollution can be overcome with the use of green energy forms like ethanol, biogas, electricity, hydrogen, etc., especially energy produced from renewable and industrial feedstocks. In hilly areas, pine needles are the most abundant biomass that has a low possibility of valorization due to high lignin content. On the other hand, anaerobic digestion (AD) of lignin and animal waste has low biogas yield due to poor conductivity. This study focuses on the simultaneous production of biogas and electricity through the co-digestion of cow dung and pine needles. The digester was initially established and stabilized in the lab to ensure a continuous supply of inoculum throughout the experiment. The optimization process involved the determination of an ideal cow dung-to-water ratio and selecting the appropriate conductive material that can enhance the energy generation from the feedstock. Afterward, both batch and continuous anaerobic digestion experiments were conducted. The results revealed that the addition of powdered graphite (5 mM), activated charcoal (15 mM), and biochar (25 mM) exhibited maximum voltage of 0.71 ± 0.013 V, 0.56 ± 0.013 V, and 0.49 ± 0.011 V on the 30th, 25th and 20th day of AD, respectively. The batch experiment showed that 5 mM graphite powder enhanced electron transfer in the AD process and generated a voltage of 0.77 ± 0.014 V on the 30th day, indicating an increase of ~1.5-fold as compared to the control (0.56 ± 0.019 V). The results from the continuous AD process showed that the digester with cow dung, pine needle, and a conductive material in combination exhibited the maximum voltage of 0.76 ± 0.012 V on the 21st day of AD, while the digester with cow dung only exhibited a maximum voltage of 0.62 ± 0.015 V on the 22nd day of AD, representing a 1.3-fold increase over the control. Furthermore, the current work used discarded plastic items and electrodes from spent batteries to emphasize waste management and aid in attaining sustainable energy and development goals.

Electrochemical treatment of 4-chlorophenol by three-dimensional electrode reactors packed with plastic particles electrodes

The three-dimensional electrode reactors (TDER) filled with surface-modified plastic particles electrodes, was much more effective on electrolyzing 4-chlorophenol wastewater than by conventional electrolysis. The experimental results indicated that about 96.8 % of 4-chorophenol was degraded effectively, it was possibly decomposed into aromatic organic compounds and small-molecular organic acids by hydroxyl radicals generated on the surfaces of electrodes, and the biodegradability of treated 4-chlorophenol wastewater was also much more improved than that of the untreated, which would be more easily biologically degraded by the subsequent conventional activated sludge process. Furthermore, the 4-chorophenol wastewater could be co-degraded with high-concentration nitrate effectively, both 2-chlorophenol and 2,4-dichorophenol wastewaters were also similarly decomposed.

New Plastic Crystal Composite Electrodes Employing Delocalized Transition Metal Salts for Low-Cost, High-Safety All-Solid-State Salt Batteries

New Plastic Crystal Composite Electrodes Employing Delocalized Transition Metal Salts for Low-Cost, High-Safety All-Solid-State Salt Batteries

Digital fabrication of 3D printed bismuth sparked sensors for electrochemical sensing

The fast and in-house fabrication of high-performance metal-based sensors is highly desirable in modern electrochemistry. Compared with plain carbon electrodes, metal-modified sensors offer wider applicability and higher sensitivity to electroanalytical methods. Herein, we introduce the entirely digital fabrication of biodegradable 3D printed thermoplastic sensors, in-situ modified with "green" spark discharge generated bismuth particles (BiPs). The hybrid fabrication process of these metal/plastic sensors employs two different printing methodologies, including fused deposition modeling for the 3D printing of the plastic electrode and printing via sparking for the deposition of BiPs on the electrode surface. More specifically, the sensors are 3D printed from a carbon black/polylactic acid filament by a 3D printer and then are modified with BiPs through repetitive sparking spots, applying an electrical discharge at 1.2 kV between a Bi-tip and the 3D printed electrode. The sparking process is performed using a desktop device equipped with a Bi-sparking head and a high voltage power supply. Full control of the sparking head movements by custom g-code software allows for the toposelective application of a predetermined number of sparking spots over the electrode surface. These ready-to-use 3D printed metal/plastic sensors are tested for the anodic voltammetric determination of lead and cadmium and the cathodic voltammetric determination of riboflavin in real samples, offering low limits of detection. These features highlight the potential of the 3D printed sparked sensor as a new generation candidate for the development of printed-at-point and sensitive metal-based sensors.

Development of an electrochemical device based on aptasensors for the determination of caffeine in beverages

Herein, we constructed a miniature electrochemical device for highly sensitive and selective detection of caffeine in beverages. A disposable gold-film plastic electrode was modified with the caffeine-specific aptamer to serve on the working electrode. It was then equipped in a detachable three-electrode test system to perform the electrochemical measurements. The whole device is robust, cost-effective, easy to fabricate, and convenient to maintenance. The preparation of the proposed device was carefully characterized and optimized. Under optimal analytical conditions, the concentration of caffeine in the range of 0.1 − 50 nM showed a good linear relationship, and the detection limit was as low as 0.079 nM. The developed method also exhibited good stability and selectivity. The practicality of this device was certified by testing the caffeine concentration in beverages on the market and comparing the results with the method based on UPLC-HRMS.

Exceptional Performance of 3D Additive Manufactured NiFe Phosphite Oxyhydroxide Hollow Tubular Lattice Plastic Electrode for Large‐Current‐Density Water Oxidization

In this article, we report a 3D NiFe phosphite oxyhydroxide plastic electrode using high‐resolution digital light processing (DLP) 3D‐printing technology via induced chemical deposition method. The as‐prepared 3D plastic electrode exhibits no template requirement, freedom design, low‐cost, robust, anticorrosion, lightweight, and micro‐nano porous characteristics. It can be drawn to the conclusion that highly oriented open‐porous 3D geometry structure will be beneficial for improving surface catalytic active area, wetting performance, and reaction–diffusion dynamics of plastic electrodes for oxygen evolution reaction (OER) catalysis process. Density functional theory (DFT) calculation interprets the origin of high activity of NiFe(PO3)O(OH) and demonstrates that the implantation of the –PO3 can effectively bind the 3d orbital of Ni in NiFe(PO3)O(OH), lead to the weak adsorption of intermediate, make electron more active to improve the conductivity, thereby lowing the transform free energy of *O to *OOH. The water oxidization performance of as‐prepared 3D NiFe(PO3)O(OH) hollow tubular (HT) lattice plastic electrode has almost reached the state‐of‐the‐art level compared with the as‐reported large‐current‐density catalysts or 3D additive manufactured plastic/metal‐based electrodes, especially for high current OER electrodes. This work breaks through the bottleneck that plagues the performance improvement of low‐cost high‐current electrodes.

Early diagnosis of autoimmune diseases through electrochemical biosensing using a modified plastic chip electrode.

Detecting chronic autoimmune disorders (ADs) early reduces the risk of morbidity, disability, and mortality and offers the possibility of significant therapeutic action in a timely manner. Developing low-cost, reliable, and sensitive sensors for ADs can ensure the efficient utilization of healthcare resources at earlier stages. Here, we report on the development of an electrochemical biosensor for sensing CXCL10, a chemokine protein that serves as a biomarker for autoimmune diseases. A self-assembly strategy is used for the immobilization of biorecognition elements on a plastic chip electrode (PCE). A homemade PCE offers a versatile and cost-effective scaffold for sensing applications. Gold nanoparticles were electrochemically deposited on the electrode via the reduction of gold ions on the PCE galvanostatically. The CXCL10 antibody and recognition elements were immobilized on the gold-deposited PCE. The attachment of recognition molecules was confirmed by energy-dispersive scanning electron microscopy, atomic force microscopy, infrared spectroscopy, and electrochemical techniques. Electrochemical impedance spectroscopy (EIS) was used for the detection of CXCL10 within a concentration range spanning from pico- to micro-molar levels. The sensor exhibited remarkable linearity in both buffer and plasma solutions, with a limit of detection (LOD) of up to 0.72 pg mL-1.

From waste to energy storage: post-consumer waste expanded polystyrene/rGO composite as a high performance self-standing electrode for coin cell supercapacitors.

This research work aims to explore the potential usage of post-consumer waste expanded polystyrene (EPS) for the fabrication of self-standing electrodes by incorporating reduced graphene oxide (rGO) into it via a facile cost-effective mechanical mixing process. The π-π interaction between the expanded polystyrene and rGO is evidenced from FT-IR and Raman analysis. The elevated thermal stability of the EPS/rGO composite from thermogravimetric analysis (TGA) further confirms the interconnection between the rGO and EPS. This π-π stacking interaction between the rGO and the polystyrene molecules present in the polymer matrix enable the composite material to be interconnected throughout which is beneficial for the charge transport process. The symmetric coin cell supercapacitor fabricated using the EPS/rGO composite electrode can be operated with a high operating voltage of 1.6 V in aqueous KOH and Na2SO4 electrolytes. The devices fabricated with KOH and Na2SO4 electrolytes deliver an areal capacitance of 11.9 mF cm-2 and 10 mF cm-2 at the discharge current density of 0.1 mA cm-2. Further, the devices fabricated with the KOH and Na2SO4 electrolytes demonstrated remarkable rate capability of 87.1% and 99.5% after 10 000 continuous charge discharge cycles. This facile method of preparation without consuming energy or polluting the environment is a novel approach which can be scaled-up to large-scale fabrication of self-standing plastic electrodes for low-cost energy storage applications.

Enhanced reduction of nitrate by TDER packed with surface-modified plastic particles electrodes

Based on Iron cathodes, nitrate could be selectively decomposed into other lower-valence nitrogen compounds, including ammonia, nitrogen gas, nitrite and nitric oxide, but the removal efficiencies of nitrate and total nitrogen (TN), are affected significantly by the synergistic effects of anodes, chloride electrolyte and conductive plastic particles electrodes. In this work, the base material Titanium (Ti) metal plates and plastic particles which surfaces were mainly coated with Ru-Sn oxidizing compounds, were applied as plates anodes and conductive particles electrodes in Three Dimensional Electrode Reactors (TDER). The Ti/RuSn plate anodes showed excellent performance on degrading nitrate, more nitrogen gas (83.84%) and less ammonia (15.51%) was produced, less TN and Iron ion (0.02 mg/L) was left in the wastewater, and less amount of chemical sludge (0.20 g/L) was produced. Furthermore, the removal efficiencies of nitrate and TN were further increased by the surface-modified plastic particles, which were cheap, reusable, corrosion-resistance, easy to obtain as manufactured materials and light to be suspended in waters. The degradation of nitrate and its intermediates was enhanced possibly by the continuous synergistic reactions initiated by hydrogen radicals, which was generated on the countless surficial active Ru-Sn sites of Ti/RuSn metal plate anodes and plastic particles electrodes, among residual nitrogen intermediates, most of ammonia was selectively converted to gaseous nitrogen by hypochlorite from chloride ion reaction.

Dehydrating subsurface clayey soils using plastic electrodes: a simple, fast, and yet reliable technique

The electrokinetic process seems to be interesting to the earthwork portion on the construction of buildings, and transportation projects since this simple, fast, yet reliable technique could expedite dehydrating of soil and reduce delays in the construction schedule. This paper examined the technical feasibility and a brief cost analysis of using plastic electrodes for electrokinetically dehydrating clayey soils with high moisture content were also carried out. The results from the experimental program carried out on a marine clayey soil with copper and plastic electrodes showed a great deal of soil improvement since positive changes in undrained shear strength occur due to the free water dehydration process induced by electroosmosis and to the adsorbed water dehydration process induced by electromigration. It was also observed that values of the undrained shear strength remained stable at the final stages of the electrokinetic process indicating a permanent soil improvement. Finally, it was noticed that dehydrating could be achieved at lower costs by employing plastic electrodes.

High Conductivity, Semiconducting, and Metallic PEDOT:PSS Electrode for All-Plastic Solar Cells.

Plastic electrodes are desirable for the rapid development of flexible organic electronics. In this article, a plastic electrode has been prepared by employing traditional conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and plastic substrate polyethersulfone (PES). The completed electrode (Denote as HC-PEDOT:PSS) treated by 80% concentrated sulfuric acid (H2SO4) possesses a high electrical conductivity of over 2673 S/cm and a high transmittance of over 90% at 550 nm. The high conductivity is attributed to the regular arrangement of PEDOT molecules, which has been proved by the X-ray diffraction characterization. Temperature-dependent conductivity measurement reveals that the HC-PEDOT:PSS possesses both semiconducting and metallic properties. The binding force and effects between the PEDOT and PEI are investigated in detail. All plastic solar cells with a classical device structure of PES/HC-PEDOT:PSS/PEI/P3HT:ICBA/EG-PEDOT:PSS show a PCE of 4.05%. The ITO-free device with a structure of Glass/HC-PEDOT:PSS/Al4083/PM6:Y6/PDINO/Ag delivers an open-circuit voltage (VOC) of 0.81 V, short-circuit current (JSC ) of 23.5 mA/cm2, fill factor (FF) of 0.67 and a moderate power conversion efficiency (PCE) of 12.8%. The above results demonstrate the HC-PEDOT:PSS electrode is a promising candidate for all-plastic solar cells and ITO-free organic solar cells.

POM@PMO plastic electrode for phosphate electrochemical detection: a further improvement of the detection limit

The development of a highly sensitive electrochemical sensor (E-sensor) is described based on stand-alone plastic electrodes (PE) for phosphate detection, being an essential nutrient in the marine environment. The detection mechanism is based on the chemical affinity between polyoxomolybdate anions (POM) and orthophosphate to form an electroactive phosphomolybdate complex. The custom-made E-sensor was formulated with an organic octamolybdate derivative (TBA4Mo8O26) incorporated with periodic mesoporous organosilica (PMO) to obtain a significant improvement in the analytical performances of phosphate determination. This POM@PMO combination was found to be advantageous in the determination of low concentrations of phosphate in standard solutions ranging from 1 to 500 nM, using square wave voltammetry as the detection technique. This sensitivity enhancement can be attributed to the effect of hydrophobic PMO in loading more POM moieties, owing to its highly porous structure and charged shell. Consequently, the POM@PMO-PE sensor achieved a competitive sensitivity of 4.43 ± 0.14 μA.nM−1.cm−2 and a limit of detection of 0.16 nM with good selectivity against silicates. Finally, seawater and treated wastewater samples have been tested to validate the sensor response in comparison to the official method of phosphate determination.Graphical abstract

In-situ evolution of bimetallic Fe/ Ni/ Co nanohybrids on MXene for improved electrocatalytic oxygen evolution reaction

Oxygen evolution reaction (OER) is a vital electrochemical reaction for sustainable energy generation technologies. Due to the sluggish kinetics, exploration for an efficient non-precious metal catalyst is essential. Bimetallic nanohybrids are potential electrocatalysts for the OER due to their pore structure, large surface area, and inevitably dispersed metal centers. This work reports the synthesis of three bimetallic Ni–Co (NCMX), Fe–Co (FCMX), and Fe–Ni (FNMX) nanohybrids onto MXene for effective OER activity. An improved OER activity is observed on a plastic chip electrode (PCE) loaded with electrocatalysts. Among the synthesized electrocatalysts, NCMX exhibits excellent OER performance with an overpotential of 220 mV and a small Tafel slope of 94 mV/dec in a basic electrolyte (1 M KOH). The 3D MXenes framework promotes strong interaction with efficient charge transfer between the nanohybrids and MXene. Results demonstrate a promising recommendation for designing high-performance MXene-supported bimetallic nanohybrid electrocatalysts.

Multiwavelength Color Switching from Polyaniline‐Viologen Bilayer: Inching toward Versatile All‐Organic Flexible Electrochromic Device

AbstractSearch for a versatile flexible all‐organic liquid electrolyte‐less solid–state electrochromic device continues. In this quest, a polyaniline‐Viologen‐(PANI‐EV)‐based electrochromic device has been reported and designed based on the complementary redox behavior and easy processibility. Electrochromic electrodes are first individually characterized before the device fabrication, to check their compatibility. The polyaniline electrode is electrodeposited and characterized using scanning electron microscopy and Raman techniques followed by bias dependent absorbance measurements to understand its color switching capabilities. In situ kinematics are performed on the finished solid–state device and electrochromic performance have been measured. An improved electrochromic performance can be observed as evident from <1 s switching time while switching with a color contrast of ≈75% and good cycle life. The device displays switching in visible, as well as IR and NIR regions with an application of bias as low as 1.5 V. In addition to the multiple wavelength switching, a device has also been fabricated on a plastic electrode to demonstrate all‐organic flexible liquid electrolyte less solid–state versatile electrochromic device.

Nanocomposite-Based Electrode Structures for EEG Signal Acquisition

Objective: To fabricate a lightweight, breathable, comfortable, and able to contour to the curvilinear body shape, electrodes built on a flexible substrate are a significant growth in wearable health monitoring. This research aims to create a GNP/FE electrode-based EEG signal acquisition system that is both efficient and inexpensive. Methodology: Three distinct electrode concentrations were developed for EEG signal acquisition, three distinct electrode concentrations (1.5:1.5, 2:1, and 3:0). The high strength-to-weight ratio to form the tribofilm in the fabrication of the electrode will provide good efficiency. The EEG signal is first subjected to a wavelet transform, which serves as a preliminary analysis. The use of biopotential signals in wearable systems as biofeedback or control commands is expected to substantially impact point-of-care health monitoring systems, rehabilitation devices, human–computer/machine interfaces (HCI/HMI), and brain–computer interfaces (BCIs). The graphene oxide (GO), glycerol (GL), and polyvinyl alcohol (PVA) GO/GL/PVA plastic electrodes were measured and compared to that of a commercially available electrode using the biopic equipment. The GO/GL/PVA plastic electrode was able to detect EEG signals satisfactorily after being used for two months, demonstrating good conductivity and lower noise than the commercial electrode. The GO/GL/PVA nanocomposite mixture was put into the electrode mold as soon as it was ready and then rapidly chilled. Results: The quality of an acquired EEG signal could be measured in several ways including by its error percentage, correlation coefficient, and signal-to-noise ratio (SNR). The fabricated electrode yield detection ranged from 0.81 kPa−1 % to 34.90 kPa−1%. The performance was estimated up to the response of 54 ms. Linear heating at the rate of 40 °C per minute was implemented on the sample ranges from 0 °C to 240 °C. During the sample electrode testing in EEG signal analysis, it obtained low impedance with a good quality of signal acquisition when compared to a conventional wet type of electrode. Conclusions: A large database was frequently built from all of the simulated signals in MATLAB code. Through the experiment, all of the required data were collected, checked against all other signals, and proven that they were accurate representations of the intended database. Evidence suggests that graphene nanoplatelets (GNP) hematite (FE2O3) polyvinylidene fluoride (PVDF) GNP/FE2O3@PVDF electrodes with a 3:0 concentration yielded the best outcomes.

A feasible, fast and reliable method for estimating ion-site association constants in plasticized PVC ion-selective electrode membranes

A feasible, fast and reliable method for estimating ion association constants in PVC plasticized membranes of ion-selective electrodes from potentiometric data has been theoretically and experimentally substantiated. The method is based on the established fact of complete dissociation of salts of quaternary ammonium cations R4N + An‒ (except for those containing methyl substituents at the nitrogen atom) in a membrane plasticized with o-nitrophenyl octyl ether (o-NPOE). Therefore, the boundary potential at the interface of the membrane with an aqueous solution of R4N+ depends only upon the concentrations of the corresponding solution and the ion exchanger in the membrane and is independent of the presence of a lipophilic ionic additive (LIA), which makes it possible to use such ions as reference ones in the internal filling solution. If the ions studied (i+) are capable of forming ion associates with the ion exchanger, then the introduction of LIA into the membrane will lead to a decrease in the concentration of free i+ ions and to a corresponding increase in the boundary potential, from which the ion association constant can be directly calculated. The results obtained agree with the known literature data and the results of quantum chemical calculations. The prospective of applying the proposed method to the study of other membrane compositions is discussed.

A Biodegradable Polymer-Based Plastic Chip Electrode as a Current Collector in Supercapacitor Application

Here, we report the performance of a biodegradable polymer-based Plastic chip Electrode (PCE) as a current collector in supercapacitor applications. Its production was evaluated using two redox materials (conducting polymers polyaniline and poly(3,4-ethylene dioxythiophene)) and a layered material, rGO. The conducting polymers were directly deposited over the Eco-friendly PCE (EPCE) using the galvanostatic method. The rGO was prepared in the conventional way and loaded over the EPCE using a binder. Both conducting polymers and rGO showed proper specific capacitance compared to previous studies with regular current collectors. Electrodes were found highly stable during experiments in high acidic medium. The supercapacitive performance was evaluated with cyclic voltammetry, charge–discharge measurements, and impedance spectroscopy. The supercapacitive materials were also characterized for their electrical and microscopic properties. Polyaniline and PEDOT were deposited over EPCEs showing >150 Fg−1 and >120 Fg−1 specific capacitance, respectively, at 0.5 Ag−1. rGO continued to show higher particular capacitance of >250 Fg−1 with excellent charge–discharge cyclic stability. The study concludes that EPCs can be used as promising electrodes for electrical energy storage applications.

Surface tailored graphite–polymer composite electrodes through cold plasma for electrochemical applications

AbstractComposite electrodes are gradually gaining interest due to their versatile applications. plastic chip electrode (PCE) comprising of graphite and Poly(methyl methacrylate) (PMMA) is one such composite that can be fabricated by simple solution‐phase mixing followed by solvent evaporation. In this study, we report more than two times enhancement in the bulk conductance of PCE by removing the passivating superficial polymer layer above the filler, through the treatment of cold plasma. Comparative characterization of the pre‐ and posttreated electrode has been performed by scanning electron microscopy (SEM), spreading resistance imaging (SRI), contact angle, and current–voltage characteristics as well as electrochemical impedance spectroscopy (EIS). Improved electroactivity of PCE has been demonstrated through cyclic voltammetry (CV).

Removal of Mist Particles by a Two-Stage Electrostatic Precipitator Featuring Plastic Plate Electrodes

To reduce corrosion, cost, and weight, we developed a nonmetallic, two-stage electrostatic precipitator (ESP) using electrodes fabricated from carbon ink and polyethylene terephthalate (a plastic), rather than expensive corrosion-resistant metals. Five collection modules were manufactured; we varied the materials used to fabricate the high-voltage and ground electrodes. The plate-type electrodes of the collection module were made of stainless steel, carbon-coated plastic (CPC), or plastic-coated carbon (PCP). Particle removal performance was investigated by the voltages of the precharger and collection modules, the particle diameter, the airflow rate, and the particle collection area. The particles were an oil mist. The electrode material had little effect on particle removal performance. The experimental performances of two-stage ESPs featuring plastic and carbon plate electrodes met the theoretical efficiencies predicted by the Deutsch equation and Cochet charging theory. Although fluttering developed when the flow velocity exceeded 2 m/s over CPC electrodes, the use of PCP electrodes (the rigidity of which was reinforced by the plastic coatings) eliminated fluttering. Moreover, in an extremely humid condition where the water vapor continuously condensed into water droplets, the polyethylene terephthalate film of the PCP electrode ensured stable operation without spark regardless of humidity or water droplets on the surface. In summary, plastic electrodes were light and economical, while affording high removal efficiencies similar to the removal efficiencies of metals. Moreover, the PCP electrode plastic coating protected the carbon ink from abrasion and corrosion.

NiO-nanoflowers decorating a plastic electrode for the non-enzymatic amperometric detection of H2O2 in milk: Old issue, new challenge

In food supply chain, there are regulatory limitations on the use of chemicals for cleaning processing lines since the healthiness of the commodities must be guaranteed if accidently traces of these detergents and sanitizers pass to them. Hydrogen peroxide, is a commonly used sanitizer in the cleaning of the food processing lines having both bactericidal and bacteriostatic properties, however, it produces inflammatory effects on the human body. The availability of rapid systems to detect its accidental presence is therefore useful to speed up the control and apply corrective actions. In the present work, a drop casting and easily prepared plastic graphite/PVC electrode decorated with NiO nanostructures has been investigated as electrochemical sensor for the non-enzymatic amperometric determination of H2O2. The catalytic activity, dispersion, and stability of NiO nanostructures mixed with plastic nanocomposite electrode have been studied in detail. The preparation method, particularly the precipitating agents used in the synthesis of NiO nanostructures strongly influenced their morphology and porosity. Further, the electrochemical response of NiO-PE electrodes towards H2O2 resulted to be morphology-dependent. The non-enzymatic electrochemical sensor was optimized for the rapid and sensitive detection of H2O2 present in milk with no sample pre-treatments. NiO nanoflowers showed the best catalytic activity towards H2O2, a linear range that extends up to 4 mM and a LOD of 5 μM (3sd of the blank signal) were obtained.