Electroanalytical Applications Research Articles

Improvement in the performance of an electrochemical sensor for ethanol determination by chemical treatment of graphite

Abstract The present work describes the preparation and characterization of chemically treated graphite by different strategies and its use for the construction of nickel-based electrochemical sensors for ethanol determination. Chemical treatment of graphite powder was carried out under three different conditions: with nitric acid, with piranha solution (98% sulfuric acid and 30% hydrogen peroxide in the ratio of 70:30) and by the Hummers method. Treated and untreated graphite samples were characterized by scanning electron microscopy techniques (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and thermogravimetry (TG). Surface chemical groups were estimated by Boehm titration. Carbon paste electrodes were constructed using untreated and treated graphite and evaluated for adsorption of nickel ions. After that, exploring the catalytic proprieties of redox pair Ni(II)/Ni(III) the device was applied towards ethanol oxidation. From all chemical treatments evaluated, samples of graphite treated by the Hummers method presented the best analytical performance. Using the best set of experimental conditions, it was observed a linear dynamic range (LDR) between 50 and 1000 μmol L−1 with a sensitivity of 42.1 μA L mmol−1 and limit of detection (LOD) and quantification (LOQ) of 15 and 50 μmol L−1, respectively. The electroanalytical application of the sensor was performed for ethanol quantification in four distilled beverage samples (vodka, cachaca, pisco and whiskey) using amperometry. The obtained results agree with a comparative method at a confidence level of 95%. Repeatability studies for five different electrodes showed an RSD of less than 10%.

Fabrication of High-Density and Superuniform Gold Nanoelectrode Arrays for Electrochemical Fluorescence Imaging

Nanoelectrode arrays have been widely used in electroanalytical applications. The challenge is to develop low-cost and simple approaches to the fabrication of superuniform and ultrasmall nanoelectrode arrays for improving analytical performance and imaging resolution. Here, superuniform and high-density gold nanoelectrode arrays with tunable electrode diameters and interelectrode distances have been fabricated by electrodeposition, followed by a simple mechanical polishing process. The fabricated free-standing arrays have a high density (108 cm-2) of nanoelectrodes (60, 140, and 200 nm in diameter), and can be used as closed bipolar electrode arrays to image electrochemical heterogeneity with micrometer spatial resolution. With the help of a confocal microscope, individual nanoelectrodes can be visualized and resolved from the reflected light. Thus, the nanoelectrode arrays are promising in electrochemical imaging with high spatial resolution.

Photoelectroanalytical Oxygen Detection with Titanate Nanosheet – Platinum Hybrids Immobilised into a Polymer of Intrinsic Microporosity (PIM‐1)

AbstractThe polymer of intrinsic microporosity PIM‐1 is employed to disperse and deposit a Pt@titanate nanosheet photocatalyst film. The resulting microporous films allow electrolyte and oxygen permeation to give conventional oxygen reduction voltammetric responses on glassy carbon or on platinum disk electrodes in the dark. Preliminary data are presented showing that with pulsed light from a blue LED (385 nm) oxygen reduction at the electrode is effectively “switched off”. A mechanism is tentatively assigned as photocatalytic depletion of oxygen near the electrode. Photoelectrochemical current responses are observed in aqueous NaOH, NaCl, Na2HPO4 and shown to be light intensity and oxygen concentration dependent. Electroanalytical applications are suggested.

Carbon Nanotube Film Electrodes with Acrylic Additives: Blocking Electrochemical Charge Transfer Reactions.

Carbon nanotubes (CNTs) processed into conductive films by liquid phase deposition technologies reveal increasing interest as electrode components in electrochemical device platforms for sensing and energy storage applications. In this work we show that the addition of acrylic latex to water-based CNT inks not only favors the fabrication of stable and robust flexible electrodes on plastic substrates but, moreover, sensitively enables the control of their electrical and electrochemical transport properties. Importantly, within a given concentration range, the acrylic additive in the films, being used as working electrodes, effectively blocks undesired faradaic transfer reactions across the electrode–electrolyte interface while maintaining their capacitance response as probed in a three-electrode electrochemical device configuration. Our results suggest a valuable strategy to enhance the chemical stability of CNT film electrodes and to suppress non-specific parasitic electrochemical reactions of relevance to electroanalytical and energy storage applications.

Fabrication of bacteriochlorin shell/gold core nanoparticles for the sensitive determination of trichlosan using differential pulse voltammetry

The triclosan contamination in daily life has attracted great attention, and there is rare electroanalytical assay based on π-system dyes. In this work, a facile preparation and electroanalytical application of an organic dispersion containing bacteriochlorin dyes (LS11) and gold nanoparticles (AuNPs) was proposed. The organic-inorganic hybrid nanocomposites were characterized by transmission electron microscope (TEM) showing a core–shell structure with a uniform layer of dye molecules. The as-prepared nanocomposites were successfully coated onto glassy carbon electrodes, and the surface characteristics of the top most layer of the modified electrodes were examined by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and water contact angle experiments. The nanocomposite film-modified electrodes exhibited good electrochemical activity towards oxidation of triclosan. The oxidation of adsorbed triclosan occurred at a reduced overpotential, and the anodic current responses under a pre-concentration step prior to the potential scan were used for quantitative analysis. A good linear relationship from 0.01 μM to 0.5 μM was obtained using differential pulse voltammetry. The sensitivity and detection limit (S/N = 3) were 23.69 μA μM−1 and 0.03 μM, respectively. The proposed assay was applied to detect triclosan in two personal hygiene products using standard addition method, and the results showed good recoveries that ranged from 96.6% to 101.5% and from 99.3% to 103.8% for a toothpaste sample and a hand wash sample, respectively. A reference HPLC-UV method was used to evaluate the proposed electroanalytical method, and a good agreement was achieved.

Simple Method for Preparing Customizable Pyrolyzed Photoresin Carbon Electrodes Using 3D Printing

We report an accessible fabrication procedure to prepare customizable pyrolyzed photoresin electrodes (PPE) for electroanalytical applications. A stereolithography 3D printer was used to pattern carbon containing photoresin on a quartz substrate before being pyrolyzed to yield a carbon electrode with X and Y dimensions ranging from mm to a minimum feature size of approximately 200 µm as determined by optical microscopy. Stylus profilometery was used to determine PPEs have an approximate step height of 600 nm. Atomic force microscopy was employed to examine the surface roughness of PPEs, which were found to have a rms roughness of approximately 25 nm. Cyclic voltammetry with hexaammineruthenium chloride was performed to examine the electrochemical behavior of the PPEs, which was consistent with the Randles-Sevcik equation and commercial glassy carbon electrodes. Hydrodynamic voltammetry in a microfluidic device was also demonstrated.

Analytical Applications of Electrochemically Pretreated Boron‐Doped Diamond Electrodes

AbstractThe several outstanding properties of boron‐doped diamond electrodes (BDDEs) have allowed their application for various purposes, among them electrochemical sensing. However, the electrochemical response of many redox species on BDDEs can be strongly dependent on whether their surfaces are predominantly hydrogen‐ (HT) or oxygen‐terminated (OT). Fortuitously, electrochemical pretreatments themselves can be used to enrichin situthe BDEE surface in one or the other type of termination. The surface of a cathodically pretreated BBDE (CPT‐BDDE) becomes enriched in HTs, whereas that of an anodically pretreated BDDE (APT‐BDEE) becomes enriched in OTs. Thus, when suitable, the electrochemical activity of a BDDE for a given analyte may be tuned by electrochemical pretreatments, yielding enhanced sensing properties. The main purpose of this review is the compilation and discussion of papers published after 2009 reporting on electroanalytical applications based on a CPT‐BDDE or an APT‐BDDE. Procedures to perform proper electrochemical pretreatments are also discussed.

Voltammetric characterization of boron-doped diamond electrodes for electroanalytical applications

The unique properties of boron-doped diamond make it a promising electrode material for electroanalytical applications, especially for stripping voltammetry. The boron-doped diamond (BDD) electrodes prepared by chemical vapor deposition (CVD) on alumina substrates were electrochemically characterized by cyclic voltammetry. The influence was investigated of the boron dopant concentration, surface termination as well as chemical surface treatment on the kinetics of the electrode reaction. A standard redox couple, ferro/ferricyanide in aqueous solution, was employed to determine important kinetic parameters (anodic transfer coefficient, diffusion coefficient, and electron transfer rate constants) of the reaction. The effect of surface conditions of the boron-doped diamond electrodes on the kinetics of the electrodeposition of bismuth film was investigated for electrochemical applications in which bismuth film electrodes are utilized. A favourable effect of the cleaning procedures was proved, especially for the oxygen plasma-treated BDD electrode with a higher content of boron in alkaline solution. The anodic current response was increased by 109% when compared with as-grown BDD. The effect of the quality of bismuth film on analytical performance of the voltammetric sensor was verified in simultaneous analysis of heavy metals (Pb, Cd and Zn) by anodic stripping voltammetry.

Photocatalytic, nitrite sensing and antibacterial studies of facile bio-synthesized nickel oxide nanoparticles

In the present work, Nickel oxide nanoparticles (NiO NPs) were synthesized using leaves extract of C. gigantea through a solution combustion method. The NiO NPs were characterized through analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The XRD results revealed rhombohedral structured crystallites with average size of 31 nm. SEM and TEM images indicate that the nanoparticles are agglomerated with an asymmetrical shape. The optical energy bandgap of 3.45 eV was estimated using UV-diffused reflectance spectroscopy (UV-DRS). The synthesized NiO NPs have shown superior photodegradation for methylene blue (MB) dye. Further, the antibacterial activity of the prepared nanoparticles was tested against E.coli and S.aureus bacterial strains. In addition, nanoparticles were utilized for electroanalytical applicability as a novel non-enzymatic sensor in the trace level quantification of nitrite. The proposed nitrite sensor showed wide linearity in the range 8–1700 μM and good stability with a lower detection limit of 1.2 μM. • Nickel oxide nanoparticles (NiO NPs) were synthesized using Calotropis gigantea through solution combustion method. • The prepared NPs were characterized using FT-IR, XRD, SEM, EDAX, HR-TEM and voltammetric techniques. • The NiO NPs showed good performance in degradation of MB dye and better antibacterial activity against E . coli and S . aureus bacterial strains. • The NiO NPs modified electrode showed the excellent electro catalytic behavior in the electrochemical sensing of nitrite with detection limit of 1.2 μM.

Synthesis of a Conductive Glassy System Based on Inorganic Oxides and Carbon Materials and Their Possible Electroanalytical Application

New materials based on V2O5, TeO2 and a combination of graphite, graphene oxide and multiwalled carbon nanotubes were developed and tested as potential electrochemical sensors. A mixture design with three components in combination with multi-response assays based on the desirability function was used as multivariate optimization for the system composition. The optimal sensor contains graphene oxide and multiwalled carbon in approximately equal amounts. The new sensors characterizations were performed with X-ray diffraction, differential scanning calorimetry, impedance spectroscopy and cyclic voltammetry. The main advantage of this electrodes are does not requires surface activation and exhibited a potential electroanalytical performance with different targeted analytes such as ascorbic acid, aspartame and lead.

Graphene oxide quantum dots immobilized on mesoporous silica: preparation, characterization and electroanalytical application

Because of its high surface area and combination of various functional groups, graphene oxide (GO) is currently one of the most actively studied materials for electroanalytical applications. It is not practical to utilize self-supported GO on its own and thus it is commonly integrated with different supporting carriers. Having a large lateral size, GO can only wrap the particles of the support and thus can significantly reduce the surface area of porous materials. To achieve synergy from the high surface area and polyfunctional nature of GO, and the rigid structure of a porous support, the lateral size of GO must essentially be decreased. Recently reported graphene oxide quantum dots (GOQDs) can fulfil this task. Here we report the successful preparation of an SiO2-GOQDs hybrid, where GOQDs have been incorporated into the mesoporous network of silica. The SiO2-GOQDs emit a strong luminescence with a band maximum at 404 nm. The Raman spectrum of SiO2-GOQDs shows two distinct peaks at 1585 cm−1 (G-peak) and 1372 cm−1 (D-peak), indicating the presence of a graphene ordered basal plane with aromatic sp2-domains and a disordered oxygen-containing structure. Covalent immobilization of GOQDs onto aminosilica via such randomly structured oxygen fragments was proven with the help of Fourier transform infrared spectroscopy, solid-state cross-polarization magic angle spinning 13C nuclear magnetic resonance, and X-ray photoelectron spectroscopy. SiO2-GOQDs were used as a modifier of a carbon paste electrode for differential pulse voltammetry determination of two antibiotics (sulfamethoxazole and trimethoprim) and two endocrine disruptors (diethylstilbestrol (DES) and estriol (EST)). The modified electrodes demonstrated a significant signal enhancement for EST (370%) and DES (760%), which was explained by a π–π stacking interaction between GOQDs and the aromatic system of the analytes.

Reagentless fabrication of a porous graphene-like electrochemical device from phenolic paper using laser-scribing

This study fabricated a portable, high-performance, and reagentless electrochemical devices using CO2 laser-scribing process, which allowed localized carbonization of a non-conductive and low-cost polymer platform, i.e., phenolic-paper. The carbonized material was extensively characterized by Raman spectroscopy, XPS, XRD, SEM, and electrochemical impedance spectroscopy. The carbon-based electrodes were obtained from the photothermal process induced by CO2 laser radiation and subsequently subjected to electrochemical treatment to fabricate a functional material with excellent conductivity and low charge-transfer resistance. Additionally, the laser-scribed electrodes presented a porous structure with graphene-like domains, thus indicating both potential for on-site electroanalytical applications and better performance than conventional carbon electrodes.

Cover Feature: (Electroanalysis 11/2019)

ElectroanalysisVolume 31, Issue 11 Cover PictureFree Access Cover Feature: (Electroanalysis 11/2019) First published: 12 November 2019 https://doi.org/10.1002/elan.201981101AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Electroanalysis covers all branches of electroanalytical chemistry, including both fundamental and application papers as well as reviews dealing with analytical voltammetry, potentiometry, new electrochemical sensors and detection schemes, nanoscale electrochemistry, advanced electromaterials, nanobioelectronics, point-of-care diagnostics, wearable sensors, and practical applications. Volume31, Issue11November 2019 RelatedInformation

Theranostic Applications of Carbon Nanomaterial Modified Sensors: A Promising Future

Electrochemistry has always provided analytical techniques characterized by instrumental simplicity, moderate cost and portability. Over the last decade the use of nanomaterials has had a great impact on biosensing. One major advantage of nanomaterials is their potential to be utilized as non-invasive diagnostic tools. Another is the capacity for combining multiple modalities within a single probe. Nanomaterials are also ideally suited to be applied as drug-delivery systems, which may facilitate the development of a new generation of theranostics with exquisitely sensitive chemical and biological sensing capabilities. Carbon based nanomaterials are the most widely used in electroanalytic and electrocatalytic sensing applications. A critical feature that has driven the impressive success of the use of carbon based nanomaterials for electroanalytical applications most likely relates to the ability of these nanomaterials to promote electron transfer in electrochemical reactions. A number of electrochemical strategies have been explored in the development of nanomaterials based electrochemical sensors for biomedical applications. Voltammetric techniques have been extremely useful in measuring blood levels, metabolites and the urinary excretion of drugs following low doses. Carbon nanomaterials offer unique advantages that span several domains, such as a high surface-to-volume ratio, high electrical conductivity, chemical stability, biocompatibility and robust mechanical strength. Thus, they are frequently incorporated as sensing elements. Carbon nanomaterials based sensors generally have higher sensitivities and lower detection limits than their conventional counterparts. The morphologies of carbon based nanomaterials constitute an additional critical factor that enables their functionality and stable operation in the design of efficient electrochemical sensors; all of which impart influences on their electron transport kinetics. Biosensors that are based on carbon nanotubes provide a significant avenue for the detection of biomolecules for in vivo and in vitro applications. Sensors that are based on carbon nanotubes provide a significant avenue for the detection of biomolecules for in vivo and in vitro applications. Efforts have been made in our group to develop new-fangled approaches for the electrochemical detection of non-steroidal anti-inflammatory drug; antiviral drug and natural alkaloid related to hepatocellular carcinoma. The proposed nanomaterial based sensors exhibited pronounced analytical performance and provided a new and powerful paradigm in terms of novel and augmented functionality that encompasses a wide variety of applications in clinical diagnostics and biological research. The developed electrochemical sensors comprised of novel nanomaterials had great potential for enhancing and superseding the capabilities of current molecular diagnostics by allowing rapid and highly accurate diagnoses, the integration of diagnostic and therapeutic capacities and the realization of personalized medicine.

Formation of 3-Dimensional Gold, Copper and Palladium Microelectrode Arrays for Enhanced Electrochemical Sensing Applications.

Microelectrodes offer higher current density and lower ohmic drop due to increased radial diffusion. They are beneficial for electroanalytical applications, particularly for the detection of analytes at trace concentrations. Microelectrodes can be fabricated as arrays to improve the current response, but are presently only commercially available with gold or platinum electrode surfaces, thus limiting the sensing of analytes that are more electroactive on other surfaces. In this work, gold (Au), copper (Cu), and palladium (Pd) are electrodeposited at two different potentials into the recessed holes of commercial microelectrode arrays to produce 3-dimensional (3D) spiky, dendritic or coral-like structures. The rough fractal structures that are produced afford enhanced electroactive surface area and increased radial diffusion due to the 3D nature, which drastically improves the sensitivity. 2,4,6-trinitrotoluene (TNT), carbon dioxide gas (CO2), and hydrogen gas (H2) were chosen as model analytes in room temperature ionic liquid solvents, to demonstrate improvements in the sensitivity of the modified microelectrode arrays, and, in some cases (e.g., for CO2 and H2), enhancements in the electrocatalytic ability. With the deposition of different materials, we have demonstrated enhanced sensitivity and electrocatalytic behaviour towards the chosen analytes.

Synthesis and characterization of tetra-ganciclovir cobalt (II) phthalocyanine for electroanalytical applications of AA/DA/UA

Cobalt (II) phthalocyanine embedded with ganciclovir units has been synthesized by a novel method using tetracarboxylic phthalocyanine reported for the first time. The synthesized dark green colored complexes were characterized by electronic spectroscopy, elemental analysis, FT-IR, MASS and XRD. Thermal stability study reveals that the newly synthesized complex was stable up to 300 °C and XRD patterns showed amorphous nature of the complex. In the present work, the synthesized complex was characterized by cyclic voltammetry and shows the redox behavior corresponding to central metal (Co+II/Co+I) of the complex. Three biomolecules are well-separated by their oxidation peaks in simultaneous determination predicting the potentials for (-128, 335, and 723 mV) with highly increasing current. The low detection limit of AA, DA, and UA were 0.33, 0.03 and 0.10 μmol by CV method and good responses of amperometric and DPV technique. The modified tetra substituted CoTGPc/GCE exhibit an excellent electrocatalytic activity, stability, high sensitivity, good linearity, and selectivity without losing its catalytic activity and proves to be a versatile chemical sensor for commercial pharmaceutical samples, vitamin C tablets, and dopamine injections.

Scanning Electrochemical Cell Microscopy (SECCM) Chronopotentiometry: Development and Applications in Electroanalysis and Electrocatalysis

Scanning electrochemical cell microscopy (SECCM) has been applied for nanoscale (electro)activity mapping in a range of electrochemical systems but so far has almost exclusively been performed in controlled-potential (amperometric/voltammetric) modes. Herein, we consider the use of SECCM operated in a controlled-current (galvanostatic or chronopotentiometric) mode, to synchronously obtain spatially resolved electrode potential (i.e., electrochemical activity) and topographical "maps". This technique is first applied, as proof of concept, to study the electrochemically reversible [Ru(NH3)6]3+/2+ electron transfer process at a glassy carbon electrode surface, where the experimental data are in good agreement with well-established chronopotentiometric theory under quasi-radial diffusion conditions. The [Ru(NH3)6]3+/2+ process has also been imaged at "aged" highly ordered pyrolytic graphite (HOPG), where apparently enhanced electrochemical activity is measured at the edge plane relative to the basal plane surface, consistent with potentiostatic measurements. Finally, chronopotentiometric SECCM has been employed to benchmark a promising electrocatalytic system, the hydrogen evolution reaction (HER) at molybdenum disulfide (MoS2), where higher electrocatalytic activity (i.e., lower overpotential at a current density of 2 mA cm-2) is observed at the edge plane compared to the basal plane surface. These results are in excellent agreement with previous controlled-potential SECCM studies, confirming the viability of the technique and thereby opening up new possibilities for the use of chronopotentiometric methods for quantitative electroanalysis at the nanoscale, with promising applications in energy storage (battery) studies, electrocatalyst benchmarking, and corrosion research.

Effect of thickness and additional elements on the filtering properties of a thin Nafion layer

Nafion is widely used as a filtering membrane in electroanalytical applications to improve selectivity towards cations. However, the role of the thickness of Nafion on its electroanalytical performance is poorly understood. Furthermore, Nafion is often modified with additional elements without characterizing their influence on Nafion's filtering properties. To understand in-depth these uncharacterized effects on Nafion, we approach these issues systematically by studying first (i) the role of Nafion film thickness on top of a well characterized tetrahedral amorphous carbon electrode and second (ii) introducing nanodiamonds into the same Nafion films with different thicknesses. With careful electrochemical and structural analyses, we show that already ultrathin Nafion film significantly reduces limiting currents of anionic species IrCl63−/4− and uric acid. With a thicker film (~3.6μm) the selective nature of Nafion is demonstrated as anionic species are completely filtered and enrichment of cationic species Ru(NH3)62+/3+ is achieved. However, diffusion within the film controls the overall kinetics of the cation reactions and the electrochemical performance of Nafion is heavily dependent on the width of the potential window used. In addition, we show that modifying Nafion with nanodiamonds increases permeability of both cationic and anionic species. Hence, Nafion's ability for selective detection of cations is greatly reduced. Interestingly, chemical effects were also observed between nanodiamonds and an inner sphere redox probe uric acid. Thus, additional elements in Nafion do not only affect the physical structure of the film, but may produce chemical changes as well. Based on the results presented here, we emphasize the importance of an in-depth investigation to understand the case specific effects of modified Nafion films to guarantee the reliability of the sensor devices in the final application.

Microfabrication and Characterization of Gold Nanoring Electrodes on Silicon Micro Pillar for Neurochemical Sensing

Nanoelectrodes provide unique size-dependent properties such as enhanced analyte transport, low charging currents and high signal-to-noise ratio (SNR), which allow them to be utilized as a sensitive detector in several areas of electrochemistry. In recent times, there is a tremendous interest in the use of nanoscale band, disk and hemispherical electrodes for novel electroanalytical applications. One major drawback is that they do not provide a 3D geometry that are more suitable for interrogating cells and tissues because of the difficulty in fabricating such nanoelectrodes onto to a 3D platform. Besides, they are bulky and lack multiplexing and multimodal capability. In this work, we report the fabrication and characterization of a gold nanoring nanoelectrode (Au NRE) that is 165±10 nm wide and micropatterned onto a 4.6±1 µm diameter 17.5±2.5 µm long silicon (Si) micropillar with an intervening 50 nm thick hafnium oxide insulating layer. The electrochemical behavior of the Au NRE was characterized by a steady-state cyclic voltammogram with extremely high SNR of 2500 and charging currents as small as 1.5±0.3 pA. A kinetically controlled voltammetric current response, which is unique to nanoscale electrodes, is indicated by a “semicircle spectrum” from the Nyquist plot. Suggested by circuit fitting of the electrochemical impedance spectra, the NRE geometry can be varied from inlaid to nanotrench with depths controllable by the etching process, which results in differing stead-state voltammetric current and interfacial properties in terms of charge transfer resistance, constant phase element and trench resistance values. The applicability of Au NREs to electrochemical sensing is demonstrated by detecting lead, a neurotoxin at 100 ppb levels. Also, by surface-modification with multi-walled carbon nanotubes, dopamine, a neurochemical implicated in various brain disorders, is detected at a sensitivity as low as 100 nM with 1000-fold selectivity versus common interferences.

Etched and non-etched polystyrene nanoballs coated with AuNPs on Indium Tin Oxide (ITO) electrode as H2O2 sensor

In electro-analytical applications, metallic nanoparticles (NPs) facilitate roughening of the conductive sensing interface and electrochemical signal amplification as a result of some metal NPs catalytic properties. In this study, natural lithography, termed as nanospheres lithography (NSL), was used to fabricate 5 nm thick AuNPs from thermal evaporation system on an Indium Tin Oxide (ITO) substrate patterned with polystyrene (PS) nanoballs (d=100 nm). The electrode substrate was characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and cyclic voltammetry (CV) and utilized as a sensor to measure H2O2. More prominent features were shown by the etched PS on the fabricated electrode that left AuNPs honeycomb-like pattern than the non-etched one. Higher oxidation peak was demonstrated by the etched electrode than non-etched electrode as recorded with cyclic voltammogram, as well as in H2O2 measurement. CV outcomes denoted higher surface area at the substrate with etched PS and resulted in a lower limit of detection (LOD) of H2O2 than the non-etched substrates.