Electrochemical Techniques Research Articles

Tethered heme domains in a triheme cytochrome allow for increased electron transport distances.

Decades of research describe myriad redox enzymes that contain cofactors arranged in tightly packed chains facilitating rapid and controlled intra-protein electron transfer. Many such enzymes participate in extracellular electron transfer (EET), a process which allows microorganisms to conserve energy in anoxic environments by exploiting mineral oxides and other extracellular substrates as terminal electron acceptors. In this work, we describe the properties of the triheme cytochrome PgcA from Geobacter sulfurreducens. PgcA has been shown to play an important role in EET but is unusual in containing three CXXCH heme binding motifs that are separated by repeated (PT)x motifs, suggested to enhance binding to mineral surfaces. Using a combination of structural, electrochemical, and biophysical techniques, we experimentally demonstrate that PgcA adopts numerous conformations stretching as far as 180 Å between the ends of domains I and III, without a tightly packed cofactor chain. Furthermore, we demonstrate a distinct role for its domain III as a mineral reductase that is recharged by domains I and II. These findings show PgcA to be the first of a new class of electron transfer proteins, with redox centers separated by some nanometers but tethered together by flexible linkers, facilitating electron transfer through a tethered diffusion mechanism rather than a fixed, closely packed electron transfer chain.

Nanomolar level detection of phosphodiesterase 5 inhibitor drug tadalafil based on halide perovskite@HNTs nanocomposite electrode

As halide perovskites have taken a central role in the evolution of semiconductor materials, they are setting new standards for performance and revolutionizing the energy sectors. Unfortunately, little light is shed on the material's electrochemical sensing capabilities. This work reports the synthesis and characterization of a novel double halide perovskite Cs2CaSnCl6 (HDP) integrated with halloysite nanotubes (HNTs) for the electrochemical detection of Tadalafil (TAD). HDP@HNTs nanocomposite is synthesized using a simple solvothermal method and is characterized using various techniques like SEM, TEM, UV-visible, FT-IR, TGA/DTA, XRD and BET analysis. The results obtained from these characterizations confirmed the successful formation of the nanocomposite, revealed the material's endurance to high temperatures and the availability of a large surface area for reaction. Electrochemical characterization techniques like cyclic voltammetry (CV) and linear sweep voltammetry (LSV) demonstrated a linear correlation with the concentrations of TAD. Computational analysis of the TAD structure optimization, molecular electrostatic potential (MEP) of TAD and calculations regarding the HOMO-LUMO molecular orbitals are all carried out using the DFT/B3LYP method. The HDP@HNTs sensor is capable of achieving the lowest detection limit of 1.68 nM and the limit of quantification of 5.09 nM. The material showcased a remarkable sensitivity of 0.0104 µA nM-1 cm-2 from all the electrochemical parameters. Its reliability and stable performance even in the presence of real samples makes it a promising material for sensing applications. Thus, the reported framework contributes to the advancement in the development of sensors and enhanced healthcare outcomes.

Target detection and simultaneous degradation of furazolidone by molecularly imprinted CoWO4/g-C3N4

In this study, a "Two birds with one stone" strategy was employed to concurrently address the challenges of electrochemical detection and photocatalytic degradation of the environmentally hazardous furazolidone (FRZ). An innovative molecularly imprinted CoWO4/g-C3N4 (i.e. MIP-CoWO4/g-C3N4) nanomaterials was constructed through a combination of hydrothermal and electrochemical polymerization techniques. The resulting MIP-CoWO4/g-C3N4 nanocomposites can be served as an exceptional sensing platform for FRZ detection, demonstrating low detection limit (2.61×10−13 mol L−1), considerable sensitivity (2.03 μA. nM−1. mm−2), excellent selectivity and decent stability. Meanwhile, the MIP-CoWO4/g-C3N4 nanocomposites exhibited remarkable photocatalytic efficiency for FRZ degradation (79.87 %). In addition, the systematic investigation into the impact of operational reaction parameters on both the electrocatalytic and photocatalytic reactions was conducted, elucidating the plausible mechanisms for both detecting and degrading FRZ. This research provides firm foundation for the development of multifunctional nanomaterials, further advancing the "integration of diagnosis and treatment" in environmental management and control.

Evaluation of 14-(p-tolyl)-14H-dibenzo[a,j]xanthene as a Highly Efficient Organic Corrosion Inhibitor for Mild Steel in 1 M HCl: Electrochemical, Theoretical, and Surface Characterization

Corrosion of mild steel, particularly in acidic environments such as hydrochloric acid (HCl), remains a critical issue due to its impact on material durability, economic costs, and safety concerns. This study introduces 14-(p-tolyl)-14H-dibenzo[a,j]xanthene (ZM5), a novel and highly effective organic corrosion inhibitor, to mitigate this challenge. Employing advanced electrochemical techniques: electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), we evaluated ZM5’s performance in a 1M HCl solution, revealing an impressive inhibition efficiency of 94.7%. Surface characterization using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) further confirmed the formation of a robust protective film on the steel surface, shedding light on ZM5’s adsorption mechanisms. Complementing the experimental findings, Density Functional Theory (DFT) simulations provided theoretical insights into the anti-corrosion mechanism of ZM5, aligning well with observed results. These findings underscore ZM5's potential as a highly promising corrosion inhibitor for industrial applications, effectively enhancing the corrosion resistance of mild steel in aggressive environments.

Graphene electrochemical biosensors combining effervescent solid-phase extraction (ESPE) for rapid, ultrasensitive, and simultaneous determination of DA, AA, and UA

Simultaneous monitoring of key metabolites like dopamine, ascorbic acid, and uric acid is essential for early disease diagnosis and evaluating treatment. Electrochemical techniques are increasingly used for precise, point-of-care testing (POCT) of these metabolites. Herein, a sample pretreatment method called effervescent solid-phase extraction (ESPE) was proposed for efficient enrichment of trace analytes for electrochemical detection. In an ESPE process, effervescent tablets made of gold nanoparticle-decorated graphene oxide (Au/GO) were first self-dispersed in a test solution to promote the enrichment of analytes on the Au/GO adsorbents, followed by the addition of flocculant effervescent tablets to cause Au/GO sheets to form self-assembled aggregates, which then can be efficiently collected by the foam electrodes. The entire sample pretreatment process operates without external power and takes only 5 min. With the assistance of the ESPE method, our electrochemical sensors achieve an ultralow detection limit for dopamine, ascorbic acid, and uric acid of 80 pM, 1.8 nM, and 460 pM, respectively, which are two to three orders of magnitude lower than the results obtained by the drop casting technique. The enhancement mechanism of our approach is based on increasing the contact probability with analytes through dynamic dispersion of the Au/GO adsorbents, in contrast to the static diffusion mechanism relied on Brownian motion. We also show that combining the ESPE solution kit with a portable micro-electrochemical workstation can attain the same detection level as HPLC in real urine samples. The proposed ESPE approach holds great promise for POCT applications in 2D material-based biosensors.

Relationships of ternary activities for the enhanced Cr(VI) removal by coupling nanoscale zerovalent iron with sulfidation and carboxymethyl cellulose

Nanoscale zerovalent iron (nZVI) has been extensively applied in water pollution control. However, the reactivity of nZVI toward contaminants is mainly limited by its corrosion and agglomeration. In this study, the nZVI modified by sulfidation coupled with carboxymethyl cellulose (CMC) (C-S-nZVI) was synthesized and characterized by TEM and electrochemical techniques. Taking Cr(VI) as the contaminant, it was found that the sulfidation could couple with CMC modification to not only enhance the reactivity of nZVI toward Cr(VI), but also regulate the sedimentation activity and corrosion activity of nZVI in water. Particularly, the optimal kobs (0.0816 min−1) obtained by the C-S-nZVIone-0.16 (i.e., one-step sulfidation and its S/Fe molar ratio was 0.16) was approximately 27.2 times higher than that by the nZVI (0.0030 min−1). Moreover, based on the correlation analysis of the ternary activities, this study confirmed that the reactivity of C-S-nZVI toward Cr(VI) was negatively correlated with its sedimentation activity (slope = −0.7623, R = 0.59) and corrosion activity (slope = −0.0171, R = 0.56), respectively. XPS and TEM results further revealed that CMC could couple with iron sulfides (FeSx) to enhance the mass transfer of Cr(VI) toward nZVI and subsequent electron transfer from Fe0 core to out, ultimately improving the reduction of Cr(VI) by nZVI. Overall, this study introduced a new evaluation method based on the ternary activity of nZVI, providing theoretical support for the practical application of nZVI-based technology.

Investigation of Corrosion Inhibition of Carbon Steel by Using Natural Iraqi Plum Tree Gum in a Saline Medium

In response to the growing interest in green chemistry and the adoption of environmentally friendly and cost-effective compounds in industrial and agricultural applications, this study focuses on exploring the potential of natural compounds. Specifically, the research investigates the corrosion inhibitory properties of Iraqi plum tree gum. The natural gum is characterized using Fourier transform infrared spectroscopy to identify its functional groups and atomic force microscopy (AFM) for further analysis. The electrochemical polarization technique was used to study corrosion measurements for carbon steel (C.S) in saline solution and in the presence of the inhibitor (Plum Tree Gum) in different concentration solutions. The findings revealed a positive correlation between the concentration of plum tree gum and the efficiency of the inhibitor, indicating that higher concentrations of the gum result in increased inhibitory effectiveness.

Electronically Weakly Coupled 4,4′‐Divinylazoarylenes‐Bridged Diruthenium Complexes Featuring Two Ru(CO)Cl(PiPr3)2 Entities

AbstractWe report here on four novel 4,4′‐divinylazoarylenes‐bridged diruthenium complexes featuring two Ru(CO)Cl(PiPr3)2 entities with a general formula of [{Ru(CO)Cl(PiPr3)2}2(μ‐{CH=CH−Ar}2‐N=N‐4,4′)]; Ar=C6H4; [1 azo], C6H3‐2‐Me; [2 azo], C6H3‐(Me)2‐2,6; [3 azo], and C6H2‐(iPr)2‐2,6; [4 azo]. Those five‐coordinated, square‐pyramidal, 16‐valence electrons (VEs) type‐complexes [1 azo]–[4 azo] were successfully synthesized by the stereo‐and regiospecific insertion of the Ru−H bond of the hydrido substrate HRu(CO)Cl(PiPr3)2 into the two terminal acetylenic bonds of the corresponding 4,4′‐diethynylated azoarylenes [L1]–[L4]. They were routinely characterized in their neutral state by traditional IR, UV/Vis and NMR spectroscopic techniques, and in their two‐closely accessible oxidized states by IR, UV/Vis/NIR spectroelectrochemistry along with electrochemical techniques as well as by (TD)‐DFT calculations. Detailed electrochemical studies on these complexes and IR, UV/Vis/NIR spectro(electro)scopic characterization of their oxidized forms along with (TD)‐DFT calculations revealed to massive 4,4′‐divinylazobenzene linker contributions to the two redox processes in addition to the noteworthy negligible electronic interaction “communication” between the two remote redox‐active end‐groups, rendering them as unique weakly coupled borderline class I/II MV systems in accordance with the Robin and Day classification. Incorporating the four bulky iPr substituents into the ortho‐positions of the 4,4′‐divinylazobenzene linker results to a significant decrease in the tendency of the co‐planarity of the bridge.

A three-components-based disposable electrochemical sensor for the detection of heavy metal ions in water

The development of an efficient sensor based on a novel three-components nanocomposite is presented for the detection of heavy metal ions (Cd2+ and Pb2+) in water. For the preparation of three-components nanocomposite surface, the polydopamine reduced graphene oxide (PyDA/RGO) composite was initially prepared by a one-step polymerization of dopamine (DA) on RGO followed by surface modification of the prepared composite with cysteine (Cys). The formation of three-components nanocomposite surface (i.e., Cys/PyDA/RGO) was initially confirmed through physical characterization techniques, including X-ray diffraction and infrared spectroscopy, whereas scanning electron microscopy revealed the surface morphology after each step of sensor fabrication. The electrochemical properties of the sensing platform were evaluated through electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy with an external ferri‐−/ferrocyanide redox probe. The prepared three-components nanocomposite on disposable pencil graphite electrode (Cys/PyDA/RGO/PGE) showed an improved charge transfer rate as compared to PyDA/RGO/PGE and bare PGE electrode. Targeted heavy metal ions were detected on the sensor surface using differential pulse voltammetry with greater sensitivity, showing detection limits of 0.77 and 1.13 ppb for Cd+2 and Pb+2 ions in citrate buffer solution, respectively. The sensor demonstrated comparable performance in the tap water samples.

Polyoxometalate/α-Fe2O3/polyaniline composite: Tailored approaches for high-performance supercapacitors

The need for portable, high-performance electronics that have high power or energy density has increased significantly in recent years. In this work, a composite material was coated on stainless steel that consists of polyoxometalate (POM)/α-Fe2O3/polyaniline (PANI) as an electrode material for a symmetric supercapacitor. α-Fe2O3 was prepared using starch as a template while PANI was electrodeposited. The physical and chemical characteristics of the modified electrodes were investigated via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic chargedischarge (GCD) experiments. In 1 M H2SO4, the composite had a specific capacitance of 528 F/g at a current density of 0.2 A/g. In addition, the composite exhibited a high energy density of 73.4 Wh kg−1 at a high-power density of 7.14 kW kg−1 and 91.62 % capacity retention after 10 cycles. The results show that POM/α-Fe2O3/PANI is a promising composite electrode for use as a supercapacitor electrode material.

Disruption Dynamics and Charge Transfer of a Single Attoliter Emulsion Droplet Revealed by Combined Fast-Scan Sinusoidal Voltammetry and Short Time Fourier Transform Analysis.

Single-entity electrochemistry has gained significant attention for the analysis of individual cells, nanoparticles, and droplets, which is leveraged by robust electrochemical techniques such as chronoamperometry and cyclic voltammetry (CV) to extract information about single entities, including size, kinetics, mass transport, etc. For an in-depth understanding such as dynamic interaction between the electrode and a single entity, the unconventional fast electrochemical technique is essential for time-resolved analysis. This fast experimental technique is unfortunately hindered by a substantial nonfaradaic response. In this work, we introduce fast-scan sinusoidal voltammetry (FSSV) combined with a short-time Fourier transform (STFT) for analyzing single emulsion droplets. Utilizing ultramicroelectrode and fast potential sweeps up to apparent 200 V/s, we achieved high temporal resolution (8 ms per voltammogram) to capture the current signals during droplet collisions. STFT analysis reveals the amplitude and phase changes, allowing for the accurate detection of collision events even in the absence of redox species. By adopting an algorithm of drift-free baseline subtraction, a conventional CV shape was obtained in FSSV. The reacted charge from the single-entity voltammogram at every 8 ms was also plotted. This method effectively addresses limitations in traditional techniques, providing insights into emulsion dynamics such as droplet contact and droplet breakdown.

Unravelling the effect of crystal lattice compression on the supercapacitive performance of hydrothermally grown nanostructured hollandite α-MnO2 induced by incremental growth time

Manganese oxide (α-MnO2) nanoparticles are highly recognised for their use in supercapacitor applications. This study demonstrates the successful synthesis of flower-like and nanorods hollandite α-MnO2 by a simple one-pot hydrothermal technique at various reaction times. The synthesised nanoparticles were characterised by various physicochemical and electrochemical characterisation techniques. The influence of the various reaction times on the structural and morphological properties was evaluated by X-ray diffraction (XRD) and scanning electron microscope. XRD patterns revealed that the synthesized MnO2 nanoparticles are tetragonal structures with crystallite sizes ranging from 13.69 to 20.37 nm estimated from the Williamson–Hall method. Moreover, the functional groups and surface area were examined by Fourier transform infrared spectroscopy and Bruner–Emmert–Teller, respectively. Furthermore, the compositional elements were studied by X-ray photoemission spectroscopy and energy-dispersive X-ray spectroscopy. Finally, the electrochemical performances were studied using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS). The GCD characteristics revealed that the optimised α-MnO2 has a good capacitive behaviour, which predicts the potential application in energy storage. Electrochemical studies revealed that the 3 h-MnO2 sample exhibited a superior electrochemical behaviour and demonstrated a high specific capacitance of 132 F/g at a current density of 1A/g.

A Novel PCR-Free Ultrasensitive GQD-Based Label-Free Electrochemical DNA Sensor for Sensitive and Rapid Detection of Francisella tularensis

Biological warfare agents are infectious microorganisms or toxins capable of harming or killing humans. Francisella tularensis is a potential bioterrorism agent that is highly infectious, even at very low doses. Biosensors for biological warfare agents are simple yet reliable point-of-care analytical tools. Developing highly sensitive, reliable, and cost-effective label-free DNA biosensors poses significant challenges, particularly when utilizing traditional techniques such as fluorescence, electrochemical methods, and others. These challenges arise primarily due to the need for labeling, enzymes, or complex modifications, which can complicate the design and implementation of biosensors. In this study, we fabricated Graphene Quantum dot (GQD)-functionalized biosensors for highly sensitive label-free DNA detection. GQDs were immobilized on the surface of screen-printed gold electrodes via mercaptoacetic acid with a thiol group. The single-stranded DNA (ssDNA) probe was also immobilized on GQDs through strong π−π interactions. The ssDNA probe can hybridize with the ssDNA target and form double-stranded DNA, leading to a decrease in the effect of GQD but a positive shift associated with the increase in DNA concentration. The specificity of the developed system was observed with different microorganism target DNAs and up to three-base mismatches in the target DNA, effectively distinguishing the target DNA. The response time for the target DNA molecule is approximately 1010 s (17 min). Experimental steps were monitored using UV/Vis spectroscopy, Atomic Force Microscopy (AFM), and electrochemical techniques to confirm the successful fabrication of the biosensor. The detection limit can reach 0.1 nM, which is two–five orders of magnitude lower than previously reported methods. The biosensor also exhibits a good linear range from 105 to 0.01 nM and has good specificity. The biosensor’s detection limit (LOD) was evaluated as 0.1 nM from the standard calibration curve, with a correlation coefficient of R2 = 0.9712, showing a good linear range and specificity. Here, we demonstrate a cost-effective, GQD-based SPGE/F. tularensis DNA test suitable for portable electrochemical devices. This application provides good perspectives for point-of-care portable electrochemical devices that integrate sample processing and detection into a single cartridge without requiring a PCR before detection. Based on these results, it can be concluded that this is the first enzyme-free electrochemical DNA biosensor developed for the rapid and sensitive detection of F. tularensis, leveraging the nanoenzyme and catalytic properties of GQDs.

Comprehensive investigation of novel synthesized thiophenytoin derivative (antiepileptic drug) as an environmentally friendly corrosion inhibitor for mild steel in 1 M HCl: Theoretical, electrochemical, and surface analysis perspectives

This study evaluates the potential of N-(2,6-dimethylphenyl)-2-(5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazol-2-yl)thio)acetamide (AM16), a novel thiophenytoin derivative used as an antiepileptic drug, as a corrosion inhibitor for mild steel in 1.0 M HCl. The research focuses on AM16’s adsorption behavior and corrosion inhibition efficiency. Electrochemical techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM), were employed to assess the inhibitor’s effectiveness. The results demonstrate that AM16 achieved a corrosion inhibition efficiency of 95.7 %, with its performance improving with increasing concentration. Polarization studies reveal that AM16 acts as a mixed-type inhibitor. The adsorption of AM16 on the steel surface was modeled using the Langmuir adsorption isotherm. Surface analysis via scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) confirmed the formation of a protective layer. Experimental findings were complemented by density functional theory (DFT)-based calculations. The combined theoretical, experimental, and analytical approaches affirm the efficacy of this molecule as a corrosion inhibitor, achieving a 95.7 % inhibition rate. Polarization studies reveal that the inhibitor acts as a mixed-type inhibitor. Thermodynamic parameters suggest that the molecule chemically adsorbs onto the steel surface, following the Langmuir isotherm.

Development of graphene oxide-based biosensing platforms for label-free bioelectronic detection of pathogenic microorganisms.

A novel electrochemical nanogenosensor devoted to clinical analysis is reported for label-free detection of pathogenic microorganisms in the present work. The designed biosensor is composed of graphene oxide-modified disposable pencil graphite electrodes as a sensing platform. Escherichia coli is used as a model case. A 5'-aminohexyl-linked 22-base sequence probe representing the E. coli amplicon is immobilized onto sensor surfaces via carbodiimide chemistry. Hybridization is performed with denatured PCR amplicons of the bacteria. Detection is realized by transduction with the electrochemical impedance spectrometry technique. The selectivity of the designed genosensor is measured using Mycobacterium tuberculosis and Klebsiella pneumoniae sequences. Outstanding sensitivity is achieved with this genosensor array platform with a detection limit of 102 nM. This platform offers promise for rapid, simple, and cost-effective detection of various pathogenic microorganisms.

Electrochemical sensor for vascular endothelial growth factor based on self-assembling DNA aptamer structure

Developing vascular endothelial growth factor (VEGF) protein is essential for early cancer diagnosis and cancer treatment monitoring. This study presents the design and characterisation of an electrochemical sensor utilising a self-assembling DNA aptamer structure for the sensitive and selective detection of VEGF. The aptamer structure comprises three different parts of single-stranded DNA that are assembled prior to integration into the sensor. Polypyrrole (Ppy)-based layers were deposited onto screen-printed carbon electrodes (SPCEs) using an electrochemical deposition technique, followed by the entrapment of a self-assembled DNA aptamer structure within electrochemically formed Ppy matrix ((DNA aptamer)/Ppy). The response to the sensor toward VEGF was measured by the pulsed amperometric detection (PAD), highlighting the enhanced performance of DNA aptamer/Ppy configuration compared to bare Ppy. The sensor exhibited high sensitivity, achieving a limit of detection (LOD) of 0.21 nM for VEGF. The interaction behaviour between VEGF in the solution and the immobilise DNA aptamer/Ppy-based structure was analysed using Langmuir isotherm model. The developed electrochemical biosensor in promising for in vitro applications in early cancer diagnostics and treatment monitoring, enabling rapid screening of patient samples.

Transforming Prussian Blue Analogues: The Future-Centric Pathway to Rise of Thin Layered Double Hydroxides for Superior Water Oxidation: An Overview

Prussian blue analogues (PBAs)[1–5] have exhibited great performance towards electrochemical water oxidation because of their high activity and stability. However, there were some challenges because of their limited surface area and less accessible active sites. Herein this work, we have explored the synthesis of a Prussian blue analogue-based thin layered double hydroxide (PBA-TLDH)[6–9] through a reconstruction method. The (PBA-TLDH) possessed high surface area and a large number of active sites for enhanced electrochemical water oxidation. These PBA-LDH materials were well characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and electrochemical techniques[1,7,10–12]. The PBA-TLDH materials had a well-defined thin layered structure with the PBAs uniformly distributed in the interlayer spaces of the LDHs. The PBA-LDH catalyst showed enhanced electrocatalytic activity towards water oxidation, with a very low overpotentials up to 240 mV and current density of 10 mA cm-2,[9,13–16] have been achieved which is significantly lower than that of the pristine PBAs. Moreover, these thin layered double hydroxides material showed excellent stability over large electrochemical cycle. This work provides a new strategy for the design and synthesis of highly active and stable electrocatalysts for water oxidation.

Electrochemical synthesis, physical properties and corrosion behavior of electropolymerized polyaniline films developed on 316L stainless steel

AbstractPolyaniline (PANI) films may be developed on metallic substrates by a variety of electrochemical techniques. In the present work, PANI films were electrodeposited on AISI 316L stainless steel substrates by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP) with the objective of comparing the efficacy of each method, based on the integrity of the developed films. Cyclic voltammetry and anodic polarization were used to determine optimal electrodeposition parameters for the development PANI films using the CA and CP methods. The structure and morphology of the coatings were characterized by scanning electron microscopy, energy‐dispersive x‐ray spectroscopy, Fourier‐transform infrared spectroscopy, and ultraviolet–visible spectroscopy. Among the evaluated techniques, CV led to the formation PANI films with the best homogeneity as well as the lowest number of defects, such as cracks or pores. Subsequently, the corrosion resistance of AISI 316L steels with and without PANI was compared in a physiological saline solution (0.9% NaCl). Potentiodynamic polarization tests indicated that the PANI‐coated samples exhibited lower corrosion current density values (0.012 vs. 0.018 μA/cm2) and lower passive current density values (0.04 vs. 0.06 μA/cm2) in comparison to the bare AISI 316L steel. Additionally, long‐term monitoring by electrochemical impedance spectroscopy revealed that PANI films consistently exhibited superior polarization resistance up to 32 days of exposure in the 0.9%NaCl solution (233,000 vs. 207,000 Ωcm2).

Solar Cells: Applications and Current Opinion

Due to the manufacturing process, silicon-based solar cells have conquered the marketplace, but their cost is not economic. As a result, thin-film manufacturing was done with low-cost, appealing materials generated using less expensive, scalable, and manufacturable procedures. The motivation behind this work is to develop low-cost, high-efficiency solar cells using chemical and electrochemical techniques. Thin film solar cell structure could be presented as glass, Cu structure, CdS window material, TCO, and CdTe absorber material. The absorber and window materials include layers such as CdS and CdTe, while Cu and TCO are the back and front contacts. By using CSS and chemical bath deposition (CBD), The usual method of making this structure is to grow window (CdS) and absorber (CdTe) materials. CBD is a batch method that generates enormous quantities of Cd-containing waste solutions each time, adding to the production process's high cost. Sputtering or PVD, including high vacuum conditions, is performed with back and front contacts. This research program focuses on developing an "all chemical-solar cell" structure. This study showed that CdS and CdTe materials may be employed and electrodeposited in thin-film solar cell systems, CBD and electroless techniques. Furthermore, the back and front contacts can be coated using the CdS electrolytic bath, which is utilized for seven months without being discarded, but the CBD bath lasts 2-3 days. The deposition rate of the thin films was about 50 - 100 times greater than reported values in the literature. The efficiency of the manufactured cells was between 1 and 6%, which was reduced by the duration of time. Twenty days after manufacturing a TCO, CdS, CdTe, the short-circuit current, Cu-Ag solar cell, and open-circuit voltage deposited by all chemical and electrochemical deposition techniques were 0.8 mA/cm2 and 8.8 mV, respectively. However, consistency and reproducibility remain unresolved. The growth of CdTe nanocrystalline thin film is one of the reasons it has been identified as having nanosized tracks. High-quality CdTe layers should be developed, or in cadmium solar cells, its layered structure is the form of a cadmium window and a zinc oxide buffer layer to increase the consistency of the solar cell efficiency.

Gold-enhanced aptasensors for highly sensitive dengue detection: a cost-effective approach

The reemergence of diseases such as Dengue has spurred the development of efficient biosensing devices. This study aims to establish a rapid, cost-effective, and efficient platform for Dengue detection. The surface of the sensor was constructed by sputtering gold onto fluorine-doped tin oxide thin films, that were previously deposited on glass substrates. Varied sputtering deposition times were used. Results obtained from X-Ray Diffraction analysis showed that the films with 4-minute deposition time had the best gold surface coverage and the best cost-benefit ratio for sensor fabrication. Subsequently, the gold thin films were functionalized with the co-immobilization of a self-organized monolayer of aptamers and 6-mercapto-1-hexanol (MCH). The monolayer was analysed using the electrochemical impedance spectroscopy technique, and the ratio of 1:25 (aptamer: total thiol) was determined for surface optimization. The performance of the aptasensor was tested for the detection of the non-structural protein 1 of Dengue serotype 4 (NS1-S4). A good sensitivity of 40.2 ± 3.7 % per decade and a low detection limit of 1.25 pg/mL were obtained. The development of this platform represents an advance in the fast fabrication of aptasensors for the detection of emerging diseases such as Dengue, contributing also to the miniaturization process of point-of-care devices.