Electrochemical Methods Research Articles

Structural evolution in S-vacancy-rich Co@Co9S8 during selective benzyl alcohol electrooxidation reaction

Electrooxidation of organics using electrons as oxidants is a clean approach to produce commodity chemicals. However, designing an electrocatalyst with superior performance at low cell voltage remains a challenge. In this study, a series of VS-Co@Co9S8 electrocatalysts were fabricated by thermal reduction method using MOFs as templates. The catalytic oxidation performance and reaction mechanism of such specimens for benzyl alcohol were comprehensively analyzed by electrochemical measurement method and ex-situ structure characterization. The results show that Co@Co9S8-30 M has a unique three-dimensional (3D) micro cubic structure with abundant S vacancy (VS). These features accelerate the electrons and substrate transfer as well as provide plentiful active sites for benzyl alcohol electrooxidation reaction (BAOR). Consequently, the Co@Co9S8-30 M presented outstanding catalytic activity. The overpotential of 10 mA cm−2 (η10) was only 265.4 mV for BAOR. The conversion rate and benzoic acid selectivity were achieved to 72% and 90%, respectively. Particularly, the formation rate of benzoic acid was 7.247 mmol·gcat.−1·h−1. Moreover, the Co@Co9S8-30 M exhibited superior durability over 135 h. The coordination number of octahedral metal sites in Co9S8 did not match the number of Co 3 d orbital electrons, resulting in the weakening of bonding strength between Co and S elements. Thus, the Co@Co9S8 was reconstructed to Co3O4@CoOOH. Based on this assessment, the Co3O4@CoOOH was the active site of BAOR. This work provides theoretical guidance for the design of Co-based catalysts.

Rapid and High-Density Antibody Immobilization Using Electropolymerization of Pyrrole for Highly Sensitive Immunoassay.

Polypyrrole (Ppy) is a biologically compatible polymer that is used as a matrix, in which drugs and enzymes can be incorporated by doping. Here, we suggest an inventive application of Ppy as a biorecognition film encapsulated with an antibody (Ab) as an alternative strategy for the on-site multistep functionalization of thiol-based self-assembled monolayers. The fabrication steps of the recognition films were followed by dropping pyrrole and Ab mixed solutions onto the electrode and obtaining a thin film by direct current electropolymerization. The efficiency of Ab immobilization was studied by using fluorescence microscopy and electrochemical (EC) methods. Finally, the Ab density was increased and immobilized in 1 min, and the sensing performance as an EC immunosensor was demonstrated using α-fetoprotein with a limit of detection of 3.13 pg/mL and sensing range from 1 pg/mL to 100 ng/mL. This study demonstrates the potential for electrochemical functionalization of biomolecules with high affinity and rapidity.

Electrochemical deposition and characterization of cuprous oxide crystallites on stainless substrates: Growth mechanism and morphological analysis

In this article, we present the growth process of cuprous oxide (Cu2O) crystallites on the stainless substrates from an aqueous cupric acetic solution under electrochemical deposition method. Copper acetate (Cu(Ac)2) aqueous solution was used as the electrolyte with the applied potential and reaction time for electrodeposition were varied in this study. Pure Cu2O crystallites of cubic phase with specific surface morphologies were observed under electrodeposited at certain temperature. The specific shape of crystallites electrodeposited at 25 °C is the structure with four identical pyramid-shaped leaves pointing outward and a pointing upward stamen in the middle. The crystal growth type can be classified as the branching growth through a surface diffusion mechanism based on the growth exponent (L ∝ t1/2). The growth of Cu2O crystal is suggested to be surface diffusion of adatoms in dendrite branching growth. A mechanism for the growth of Cu2O crystals under electrodeposition was proposed based on the XPS results. As the temperature increases, the morphology of Cu2O crystals under electrodeposition becomes thinner, but the shape does not change a lot.

Electrochemical Diffusion Study in Poly(Ethylene Glycol) Dimethacrylate-Based Hydrogels.

Hydrogels are of great importance for functionalizing sensors and microfluidics, and poly(ethylene glycol) dimethacrylate (PEG-DMA) is often used as a viscosifier for printable hydrogel precursor inks. In this study, 1-10 kDa PEG-DMA based hydrogels were characterized by gravimetric and electrochemical methods to investigate the diffusivity of small molecules and proteins. Swelling ratios (SRs) of 14.43-9.24, as well as mesh sizes ξ of 3.58-6.91 nm were calculated, and it was found that the SR correlates with the molar concentration of PEG-DMA in the ink (MCI) (SR = 0.1127 × MCI + 8.3256, R2 = 0.9692) and ξ correlates with the molecular weight (Mw) (ξ = 0.3382 × Mw + 3.638, R2 = 0.9451). To investigate the sensing properties, methylene blue (MB) and MB-conjugated proteins were measured on electrochemical sensors with and without hydrogel coating. It was found that on sensors with 10 kDa PEG-DMA hydrogel modification, the DPV peak currents were reduced to 92 % for MB, 73 % for MB-BSA, and 23 % for MB-IgG. To investigate the diffusion properties of MB(-conjugates) in hydrogels with 1-10 kDa PEG-DMA, diffusivity was calculated from the current equation. It was found that diffusivity increases with increasing ξ. Finally, the release of MB-BSA was detected after drying the MB-BSA-containing hydrogel, which is a promising result for the development of hydrogel-based reagent reservoirs for biosensing.

Thiol-ene Click Chemistry Synthesis of L-Cysteine-Grafted Graphene Oxide As a New Corrosion Inhibitor for Q235 Steel in Acidic Environment.

l-cysteine, as an eco-friendly and nontoxic corrosion inhibitor, was directly covalently linked to the carbon/carbon double bonds of the GO flakes by a thiol-ene click reaction to avoid decreasing the number of hydrophilic oxygen-containing polar functionalities. The corrosion inhibition performances of Cys-GO toward Q235 steel (QS) in diluted hydrochloric acid were studied by electrochemical methods. The corrosion was a charge transfer-controlled process, and Cys-GO manifested as a mixed-type corrosion inhibitor. The corrosion inhibition efficiency (η) for QS showed a first-increase-and-then-decrease trend with increasing Cys-GO concentrations. The optimum concentration of Cys-GO was 15 mg L-1, and the according η value was up to 90%. The Cys-GO adsorbed on the QS surface to form a protective barrier was responsible for the efficient corrosion inhibition. Langmuir adsorption isotherm model was fitted well with the experiment data, indicating a monolayer adsorption. Furthermore, the coordinate covalent bonds, π-back-donation effect, and electrostatic attraction were responsible for the Cys-GO adsorption on the QS surface.

Production and New Green Activation of Conductive 3D-Printed Cu/PLA Electrode: Its Performance in Hydrogen Evolution Reactions in Alkaline Media

In this study, Cu-polylactic acid (PLA) composite filaments were produced with an extruder and three-dimensional (3D) Cu/PLA electrodes were 3D printed with Fused Deposition Modelling (FDM) method. To improve the electrochemical performance of the 3D-Cu/PLA electrode, a novel electrochemical activation method, which differentiates from complex activation methods in the literature, was applied in 1 M KOH solution without using any solvent. Field emission scanning electron microscopy (FE-SEM), Energy-Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), and RAMAN techniques were used to characterize the 3D-Cu/PLA electrode before and after activation. The results showed that Cu particles were released after the degradation of PLA after activation. In addition, the thermal stability of the 3D electrode was demonstrated by the TGA technique. The performance of the 3D Cu/PLA electrode before and after activation in the hydrogen evolution reaction (HER) in 1M solution was measured using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cathodic polarization curves methods. The EIS results showed that the charge transfers resistance values of the 3D-Cu/PLA electrode in 1 M KOH decreased significantly after activation. Post-activation hydrogen content measurements of the 3D-Cu/PLA electrode after electrolysis at different potentials and energy efficiency tests at different current densities were also carried out. The results indicate that the electrocatalytic properties of 3D-Cu electrodes were improved for HER through the activation process.

Atomically Co-dispersed nitrogen-doped carbon for sensitive electrochemical immunoassay of breast cancer biomarker CA15-3.

The development of an ultrasensitive and precise measurement of a breast cancer biomarker (cancer antigen 15-3; CA15-3) in complex human serum is essential for the early diagnosis of cancer in groups of healthy populations and the treatment of patients. However, currently available testing technologies suffer from insufficient sensitivity toward CA15-3, which severely limits early large-scale screening of breast cancer patients. We report a versatile electrochemical immunoassay method based on atomically cobalt-dispersed nitrogen-doped carbon (Co-NC)-modified disposable screen-printed carbon electrode (SPCE) with alkaline phosphatase (ALP) and its metabolite, ascorbic acid 2-phosphate (AAP), as the electrochemical labeling and redox signaling unit for sensitive detection of low-abundance CA15-3. During electrochemical detection by differential pulse voltammetry (DPV), it was found that the Co-NC-SPCE electrode did not have a current signal response to the AAP substrate; however, it had an extremely favorable response current to ascorbic acid (AA). Based on the above principle, the target CA15-3-triggered immunoassay enriched ALP-catalyzed AAP produces a large amount of AA, resulting in a significant change in the system current signal, thereby realizing the highly sensitive detection of CA15-3. Under the optimal AAP substrate concentration and ALP catalysis time, the Co-NC-SPCE-based electrochemical immunoassay demonstrated a good DPV current for CA15-3 in the assay interval of 1.0 mU/mL to 10,000 mU/mL, with a calculated limit of detection of 0.38 mU/mL. Since Co-NC-SPCE has an excellent DPV current response to AA and employs split-type scheme, the constructed electrochemical immunoassay has the merits of high preciseness and anti-interference, and its clinical diagnostic results are comparable to those of commercial kits.

Water quality constraints H2O2 production in a dual-fiber photocatalytic reactor

In-situ hydrogen peroxide (H2O2) finds applications in disinfection and oxidation processes. Photoproduction of H2O2 from water and oxygen, avoids reliance upon organic chemicals, and potentially enables smaller-sized or lower-cost reactors than electrochemical methods. In ultrapure water, we previously demonstrated a novel dual-fiber system coupling a light emitting diode (LED) with a metal-organic framework (MOF) catalyst-coated optical fiber (POF-MIL-101(Fe)) and O2-based hollow-membrane fibers and achieved a remarkable H2O2 yield, 308 ± 1.4 mM h−1 catalyst-g−1. To enable H2O2 production anywhere we sought to understand the impacts of common water quality parameters. The production of H2O2 was not affected by added sodium, potassium, hydroxide, sulfate or nitrate ions. There was consistent performance over a wide pH range (4–10), maintaining a high production rate of 232 ± 3.5 mM h−1 catalyst-g−1 even at pH 10, a condition typically unfavorable for H2O2 photoproduction. Chloride ions produced hypochlorous acid, consuming in-situ produced H2O2. Phosphate adsorption on the iron-based MOF catalysts blocked H2O2 production. Inorganic carbon species inhibited H2O2 production due to in-situ formic acid. Encouraging results were obtained using atmospheric water (i.e., condensate), with rates reaching 288 ± 6.1 mM h−1 catalyst-g−1, comparable to ultrapure water. This underscores atmospheric water as a variable alternative, available in nearly all building air conditioning systems or could overcome geographical constraints, particularly in regions where obtaining pure water resources is challenging, offering a cost-effective solution. The dual-fiber reactor using atmospheric water enables high-efficiency H2O2 production anytime and anywhere.

Porous Prussian blue nanolayers formed in situ on Fe-MOFs-modified electrode surfaces by electrochemically triggered dual-templating effect for ultrasensitive detection of lead ions and Staphylococcus aureus

In this study, introducing Fe-MOFs as reactants to the electrode surface creates a novel mode for modulating interface performance that can lead to rapid enrichment of reactants in the proximity of electrodes by electrochemical-induced confinement effect. A facile, controllable, and room temperature electrochemical approach utilizes Fe-MOFs as nanotemplates to produce porous Prussian blue (PB) nanolayers on the electrode surfaces. Unlike conventional chemical conversion that needs a supply of exogenous acid regents, the electrochemical method creates a solid acidic condition in the oxygen evolution reaction cycle to release Fe3+ from the Fe-MOFs, improving conversion efficiency and electrochemical activity of PB. Furthermore, small oxygen bubbles generated by splitting H2O near the electrodes are also good templates, promoting the formation of porous structures that can increase effective surface area and mass-transfer efficiency. As a conceptional application, using Fe-MOFs as self-sacrificial tags, an ultrasensitive electrochemical platform with triple amplification is developed to detect Pb2+ and S. aureus based on DNAzyme-CHA cascade reaction. The designed platform shows low detection limits of 8.5 fM and 1 CFU/mL for Pb2+ and S. aureus, respectively. Moreover, the platform has high selectivity, stability and reproducibility, and also shows satisfactory recovery rates when validated using actual samples.

A Comparative Analysis of the Interaction between Donepezil and Albumin with and Without a ZnO/Chitosan Quantum Dot Nanocomposite

AbstractIn this study, a nanocomposite of zinc oxide (ZnO) nanoparticles and chitosan‐based carbon quantum dots (ZnO/chQDs) in the presence of bovine serum albumin (BSA) as a promising drug carrier candidate was synthesized and characterized. For this purpose, chitosan and citric acid were used for the synthesis of chQDs and donepezil (DNP) was selected as a model drug. The BSA binding properties of DNP were analyzed by FT‐IR and UV‐Vis techniques, electrochemical methods and molecular docking in the absence and presence of ZnO/chQDs. The thermodynamic parameters and binding constants of DNP with BSA were also evaluated by these methods. The changes in the structural properties of BSA in the presence of DNP, ZnO/chQDs and ZnO/chQDs‐DNP were monitored by ATR‐FTIR spectroscopy. Cyclic and differential pulse voltammetric techniques and electrochemical impedance spectroscopy were applied to investigate the interactions, using methylene blue in electrolyte solution as redox probe, and its redox behaviour was observed to explore the interactions. Molecular docking was carried out on the interaction of DNP with BSA in the absence and presence of the synthesized ZnO/chQDs, and the results were compared with those of the experimental observations. The experimental results were confirmed by molecular docking studies.

Platinum (II) Schiff Base Complexes and their Effects on the Inhibition of Amyloid β1–42 Aggregation

For synthesizing metal–organic molecules with pro‐drug properties to prevent the accumulation of amyloid beta (Aβ1–42), which is a feature of neurodegenerative Alzheimer's disease, two new Schiff bases with imine/amine donors 2‐([3,3‐diphenylalidene]amino)‐N,N‐dimethylethane‐1‐amine and N,N‐dimethyl‐2‐([quinolin‐4‐ylmethylene]amino)ethane‐1‐amine, as well as their novel Pt (II) complexes (I and II), were synthesized and characterized via Fourier transform infrared spectroscopy, 1H‐ and 13C‐nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, and elemental analyses. The spectroscopic data has shown that the ligands are coordinated to the central atom in a chelating manner.Furthermore, the interaction between these complexes and Aβ1–42 was investigated using the electrochemical methods, square wave voltammetry and pencil graphite electrode, while monitoring the changes in the oxidation signal of the Try residue in Aβ1–42.The ability of the compounds to inhibit Aβ1–42 aggregation was investigated using the human neuroblastoma cell line (SH‐SY5Y). Complex II could actively inhibit the aggregation of Aβ1–42 at a molar ratio of 1.0/1.0, and its Aβ1–42 aggregation kinetics were fluorometrically determined using thioflavin T.These results were supported by scanning electron microscopy and transmission electron microscopy analyses. Moreover, the interaction of complex II with Aβ1–16 was investigated via 1H‐NMR spectroscopy.As a result, it was observed that complex II was effective in inhibiting the aggregation of Aβ1–42 at a molar ratio of 1.0/1.0. This result shows that studies can be conducted on the effects of Schiff base‐Pt complexes as potential pro‐drugs on Alzheimer's disease.

Healing the structural defects of spinel MnFe2O4 to enhance the electrocatalytic activity for oxygen reduction reaction

Spinel metal oxides containing Mn, Co, or Fe (AB2O4, A/B = Mn/Fe/Co) are one of the most promising non-Pt electrocatalysts for oxygen reduction reaction (ORR) in alkaline conditions. However, the low conductivity of metal oxides and the poor intrinsic activities of transition metal sites lead to unsatisfactory ORR performance. In this study, eutectic molten salt (EMS) treatment is employed to reconstruct the atomic arrangement of MnFe2O4 electrocatalyst as a prototype for enhancing ORR performance. Comprehensive analyses by using XAFS, soft XAS, XPS, and electrochemical methods reveal that the EMS treatment reduces the oxygen vacancies and spinel inverse in MnFe2O4 effectively, which improves the electric conductivity and increases the population of more catalytically active Mn2+ sites with tetrahedral coordination. Moreover, the enhanced Mn-O interaction after EMS treatment is conducive to the adsorption and activation of O2, which promotes the first electron transfer step (generally considered as the rate-determining step) of the ORR process. As a result, the EMS treated MnFe2O4 catalyst delivers a positive shift of 40 mV in the ORR half-wave potential and a two-fold enhanced mass/specific activity. This work provides a convenient approach to manipulate the atomic architecture and local electronic structure of spinel oxides as ORR electrocatalysts and a comprehensive understanding of the structure-performance relationship from the molecular/atomic scale.

Probing the Electron Accepting Ability of Phosphaphenalenes.

Phosphaphenalenes, extended π conjugates with the incorporation of phosphorus, are attractive avenues towards molecular materials for the applications in organic electronics, but their electron accepting ability have not been investigated. In this study, we present systematic studies on the reductive behavior of a representative phosphaphenalene and its oxide by chemical and electrochemical methods. The chemical reduction of the phosphaphenalene by alkali metals reveals the facile P‒C bond cleavage to form phosphaphenalenide anion, which functions as a transfer block for structure modification on the phosphorus atom. In contrast, the pentavalent P-oxide reacts with one or two equivalents of elemental sodium to form stable radical anion and dianion salts, respectively.

Electrochemical Synthesis of Ferrate (VI): Factors Influencing Synthesis and Current Research Trends

Ferrate(VI) emerges as a multifaceted substance endowed with a substantial redox potential, showcasing considerable potential for utilization in realms such as battery materials and advancements in water treatment technologies. There are primarily three methods for preparing Ferrate(VI), including peroxide heating method, hypochlorite oxidation method and electrochemical synthesis method. This review centrally delves into the electrochemical synthesis of ferrate(VI), given its mild reaction conditions, emerges as a highly potent means to synthesize Ferrate(VI) with substantial potential for industrial applications.The intricacies of influencing factors, including anode materials, electrolyte composition, electrolyte additives, reaction temperature, current density, membranes (ion-exchange membranes), and reactor types, are meticulously detailed, all of which exert a discernible influence on the synthesis process. A comprehensive exposition of the current research landscape and prevailing trends in the electrochemical synthesis of ferrate(VI) is presented. However, the current discourse on the electrochemical synthesis of Ferrate(VI) remains insufficient. Addressing these issues not only demands the optimization of reaction conditions but also necessitates the exploration of novel methodologies. For instance, incorporating the contextual application of Ferrate(VI) and achieving in-situ synthesis for immediate utilization are pivotal directions for future research and development.

Electrochemical Monitoring of Real‐Time Vesicle Dynamics Induced by Tau in a Confined Nanopipette

The microtubule‐associated protein tau participates in neurotransmission regulation via its interaction with synaptic vesicles (SVs). The precise nature and mechanics of tau's engagement with SVs, especially regarding alterations in vesicle dynamics, remain a matter of discussion. We report an electrochemical method using a synapse‐mimicking nanopipette to monitor vesicle dynamics induced by tau. A model vesicle of ~30 nm is confined within a lipid‐modified nanopipette orifice with a comparable diameter to mimic the synaptic lipid environment. Both tau and phosphorylated tau (p‐tau) present two‐state dynamic behavior in this biomimetic system, showing typical ionic current oscillation, induced by lipid‐tau interaction. The results indicate that p‐tau has a stronger affinity to the lipid vesicles in the confined environment, blocking the vesicle movement to a higher degree. Taken together, this method bridges a gap for sensing synaptic vesicle dynamics in a confined lipid environment, mimicking vesicle movement near the synaptic membrane. These findings contribute to understanding how different types of tau protein regulate synaptic vesicle motility and to underlying its functional and pathological behaviours in disease.

Electrochemical Monitoring of Real-Time Vesicle Dynamics Induced by Tau in a Confined Nanopipette.

The microtubule-associated protein tau participates in neurotransmission regulation via its interaction with synaptic vesicles (SVs). The precise nature and mechanics of tau's engagement with SVs, especially regarding alterations in vesicle dynamics, remain a matter of discussion. We report an electrochemical method using a synapse-mimicking nanopipette to monitor vesicle dynamics induced by tau. A model vesicle of ~30 nm is confined within a lipid-modified nanopipette orifice with a comparable diameter to mimic the synaptic lipid environment. Both tau and phosphorylated tau (p-tau) present two-state dynamic behavior in this biomimetic system, showing typical ionic current oscillation, induced by lipid-tau interaction. The results indicate that p-tau has a stronger affinity to the lipid vesicles in the confined environment, blocking the vesicle movement to a higher degree. Taken together, this method bridges a gap for sensing synaptic vesicle dynamics in a confined lipid environment, mimicking vesicle movement near the synaptic membrane. These findings contribute to understanding how different types of tau protein regulate synaptic vesicle motility and to underlying its functional and pathological behaviours in disease.

Experimental study of capacity fading mechanism in multiple overdischarge on LiNi0.5Co0.2Mn0.3O2&LiMn2O4/graphite lithium-ion batteries

Batteries can be overdischarged in practical applications, which does not pose safety risks. However, overdischarge can have a significant impact on battery performance. In this work, LiNi0.5Co0.2Mn0.3O2 (NCM)&LiMn2O4 (LMO)/graphite batteries are used as the main body. The failure mechanism of the batteries under different temperatures (-10 °C, 25 °C, 45 °C) and different depth of discharge (DOD) (105% DOD and 110% DOD) is studied systematically through the electrochemical methods, scanning electron microscopy (SEM), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that the deep overdischarge and high temperature accelerate the degradation of electrolyte, separator and collector, and cause rupture and recombination of solid electrolyte interphase (SEI) film. These result in the loss of conductivity, active substances and lithium ions, in which the loss of lithium ions plays a dominant role. Moreover, the attenuation of positive active material mainly comes from NCM. Our research results are of great significance for researchers to understand the failure mechanism of lithium batteries under different conditions and can provide important guidance for the safe design of lithium-ion batteries.

Fabrication of Carbon Quantum Dots/Alq3 Layer for NO2 Gas Sensor

The gas sensors were prepared using carbon quantum dots (CQDs) using an electrochemical method after mixing the CQDs with Tris (8-hydroxyquinoline) aluminum (III) (Alq3) polymer. A spin coating technique was used to deposit CQDs/Alq3 composite film on glass substrates with a ratio of 1:1. The CQDs/Alq3 gas sensor showed a sensitivity of about 24٪ at a temperature of 300 ℃, and this was calculated after measuring the change in the resistance of the samples with a response time of 2 and 8sec recovery time. The sensor showed a good response for nitrogen dioxide (NO2) gas. However, the sensitivity, response time, and recovery time for the CQDs gas sensor when exposed to NO2 gas at 300 °C were 78%, 4s, and 129s, respectively. The results showed that the best sensor CQDs/Alq3 led to a reduction in the recovery time, which shows the importance of the Alq3 polymer in improving the properties of the gas sensor.

Corrosion Inhibition Properties of Corrosion Inhibitors to under-Deposit Corrosion of X65 Steel in CO2 Corrosion Conditions.

Under-deposit corrosion is widely present in the pipelines of oil and gas production, causing significant corrosion damage. In this paper, a novel electrochemical cathodic-polarization method was carried out to accelerate the formation of CaCO3 scale on a X65 steel surface in a simulated solution containing scaling ions. Subsequently, pre-scaled X65 steel was placed in a high temperature and pressure autoclave to conduct corrosion weight-loss experiments and in situ electrochemical measurements. The study mainly compared the corrosion inhibition behavior of four quaternary ammonium salt corrosion inhibitors, pyridinium quaternary salt (BPC), quinolinium quaternary salt (BQC), 8-hydroxyquinolinium quaternary salt (BHQ) and pyridinium (1-chloromethyl naphthalene) quaternary salt (1-CPN), in a simulated oilfield scale under corrosive conditions. The results of the weight-loss experiments demonstrated that the inhibition efficiencies of the corrosion inhibitors from high to low were as follows: 1-CPN < BHQ < BQC < BPC. The in situ electrochemical measurements showed that the immersion time and type of corrosion inhibitor had a pronounced influence on the corrosion and corrosion inhibition behavior of X65 steel with CaCO3 coating. It was also proved using both EIS and PC that 1-CPN shows the best inhibition performance in all. Lastly, the inhibition mechanism of corrosion inhibitors at under-deposit conditions was analyzed via a surface morphology observation of SEM.

Iodide based electrochemical gold quantification method for lateral flow assays

The lateral flow assay (LFA) is an ideal technology for at-home medical diagnostic tests due to its ease of use, cost-effectiveness, and rapid results. Despite these advantages, only few LFAs, such as the pregnancy and COVID-19 tests, have been translated from the laboratory to the homes of patients. To date, the medical applicability of LFAs is limited by the fact that they only provide yes/no answers unless combined with optical readers that are too expensive for at-home applications. Furthermore, LFAs are unable to compete with the state-of-the-art technologies in centralized laboratories in terms of detection limits. To address those shortcomings, we have developed an electrochemical readout procedure to enable quantitative and sensitive LFAs. This technique is based on a voltage-triggered in-situ dissolution of gold nanoparticles, the conventional label used to visualize target-specific signals on the test line in LFAs. Following the dissolution, the amount of gold is measured by electroplating onto an electrode and subsequent electrochemical quantification of the deposited gold. The measured current has a low noise, which achieves superior detection limits compared to optical techniques where background light scattering is limiting the readout performance. In addition, the hardware for the readout was developed to demonstrate translatability towards low-cost electronics.