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Screen-printed carbon electrode (SPCE) was examined as a transducer substrate for application in electrochemical sensors. Aqueous solutions of 0.1 M KCl and 0.1 M KCl + 5 mM K3[Fe(CN)6]/K4[Fe(CN)6] (redox solution) were prepared to simulate the environment of faradaic and non-faradaic sensing, respectively. The SPCE presented an irregular surface composed by two main carbon phases. Raman spectroscopy results revealed the presence of peaks around 1,580 cm−1 and 1,334 cm−1 related to the G and D bands corresponding to sp2 carbon atoms (graphite flakes) and a multitude of broad bands associable to amorphous sp3 carbon in the ink matrix. Conductive atomic force microscopy indicated that the irregular structure of the SPCE led to the heterogeneous distribution of the current over the surface and the electroactivity of this material was mainly attributed to the presence of graphite. Polarization curves and electrochemical impedance spectroscopy (EIS) revealed that the redox solution was more aggressive to the SPCE, despite this electrode was achieved a quasi-steady state for 1 h under the effect of a polarization potential in both electrolytes, which justifies its use as an electrochemical transducer in faradaic and non-faradaic devices.

Corrosion of steel-reinforced concrete exposed to marine environments could lead to structural catastrophic failure in service. Hence, the construction industry is seeking novel corrosion preventive methods that are effective, cheap, and non-toxic. In this regard, the inhibitive properties of sodium phosphate (Na3PO4) corrosion inhibitor have been investigated for carbon steel reinforcements in 0.6 M Cl− contaminated simulated concrete pore solution (SCPS). Different electrochemical testing has been utilized including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky plots to test Na3PO4 at different concentrations: 0.05, 0.1, 0.3, and 0.6 M. It was found that Na3PO4 adsorbs on the surface through a combined physicochemical adsorption process, thus creating insoluble protective ferric phosphate film (FePO4) and achieving an inhibition efficiency (IE) up to 91.7%. The formation of FePO4 was elucidated by means of Fourier-transform infrared spectroscopy (FT–IR) and X-ray photoelectron spectroscopy (XPS). Quantum chemical parameters using density functional theory (DFT) were obtained to further understand the chemical interactions at the interface. It was found that PO43− ions have a low energy gap (ΔEgap), hence facilitating their adsorption. Additionally, Mulliken population analysis showed that the oxygen atoms present in PO43− are strong nucleophiles, thus acting as adsorption sites.

Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using silicon nanoparticles as the active material. In this work, the comparison of the behavior and chemical composition of the Solid Electrolyte Interphase (SEI) was carried out between Si nanoparticles and carbon-coated Si nanoparticles (Si@C). A combination of two complementary analytical techniques, Electrochemical Impedance Spectroscopy and X-ray Photoelectron Spectroscopy (XPS), was used to determine the intrinsic characteristics of the SEI. It was demonstrated that the SEI on Si particles is more resistive than the SEI on the Si@C particles. XPS demonstrated that the interface on the Si particles contains more oxygen when not covered with carbon, which shows that a protective layer of carbon helps to reduce the number of inorganic components, leading to more resistive SEI. The combination of those two analytical techniques is implemented to highlight the features and evolution of interfaces in different battery technologies.

A new electrochemical immunosensor for cancer cell detection based on a specific interaction between the metastasis-related antigen of epithelial cell adhesion molecule (EpCAM) on the cell membrane and its monoclonal antibody (Anti-EpCAM) immobilized on a gold electrode has been developed. The amino-terminated polyamidoamine dendrimer (G6 PAMAM) was first covalently attached to the 3-mercaptopropionic acid (MPA)-functionalized gold electrode to obtain a thin film, and then completely carboxylated by succinic anhydride (SA). Next, the Anti-EpCAM was covalently bound with the G6 PAMAM to obtain a stable recognition layer. In the presence of the EpCAM expressing hepatocellular carcinomas cell line of HepG2, the specific immune recognition (Anti-EpCAM/EpCAM) led to an obvious change of the electron transfer ability. The properties of the layer-by-layer assembly process was examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The final determination of HepG2 cells was performed in the presence of the reversible [Fe(CN)6]3−/4− redox couple using impedance technique. Based on the advantages of PAMAM nanomaterial and immune reaction, a linear response to HepG2 cells ranging from 1 × 104 to 1 × 106 cells mL−1 with a calculated detection limit of 2.1 × 103 cells mL−1 was obtained. We expect this method can provide a potential tool for cancer cell monitoring and protein expression analysis.

Lithium-ion batteries are electrochemical energy storage devices that have enabled the electrification of transportation systems and large-scale grid energy storage. During their operational life cycle, batteries inevitably undergo aging, resulting in a gradual decline in their performance. In this paper, we equip readers with the tools to compute system-level performance metrics across the lifespan of a battery cell. These metrics are extracted from standardized reference performance tests, also known as diagnostic tests, conducted periodically during battery aging experiments. We analyze the diagnostic tests from a publicly available dataset (Pozzato et al. in Data Brief 41:107995, 2022 ) that consists of the capacity test, high pulse power characterization test, and electrochemical impedance spectroscopy. We provide detailed calculation methodologies and MATLAB ® scripts required to extract capacity, energy, state-of-charge, state-of-energy, open-circuit voltage, internal resistance, power, incremental capacity, and differential voltage. The MATLAB ® scripts developed to generate the plots in this paper have been made accessible to the public (Ha et al. in Mendeley Data, V3, 2023 ). The primary objective of this paper is to provide an accessible guide for undergraduate and graduate students, educators, and researchers interested in characterizing the performance and health metrics of batteries. Such characterizations are critical to the development of battery aging models that can be used to improve cycle life estimation and advance battery management system algorithms.

Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving their performance. To this end, a conventional mathematical and a physicochemical model were adapted. The impedance was measured by electrochemical impedance spectroscopy (EIS). An EC consisting of electrical elements was introduced for each modeling approach. The mathematical model was purely based on a best-fit method and utilized an EC with intuitive elements. In contrast, the physicochemical model was motivated by advanced theories and allowed meaningful associations with properties at the electrode, the electrolyte, and their interface. The physicochemical model showed a higher approximation ability (relative error of 3.7%) due to the interface impedance integration in a more complex circuit design. However, this model required more modeling and optimization effort. Moreover, the fitted parameters differed from the analytically calculated ones due to uncertainties in the SSC’s microscale configuration, which need further investigations. Nevertheless, the results show that the proposed physicochemical model is promising in simulating EIS data of SSCs with the additional advantage of utilizing well-reasoned property-based EC elements.

This review presents the basic characteristics of MXene, a novel 2D nanomaterial with many outstanding properties applicable to electrochemical sensing and biosensing. The second part deals with electrochemical impedance spectroscopy (EIS) and its beneficial features applicable to ultrasensitive electrochemical sensing and label-free biosensing. The main part of the review presents recent advances in the integration of MXene to design electrochemical interfaces. EIS was used to evaluate the effect of anodic potential on MXene and the effect of the MXene preparation route and for characterization of MXene grafted with polymers. It also included the application of EIS as the main transducing tool for antibody- and aptamer-based biosensors or biosensors integrating molecularly imprinted polymers.

It is well known that corrosion protection of pure Al is enormously improved by the formation of porous anodic oxide films and by pore sealing treatment. However, the effects of anodizing and pore sealing on corrosion protection for Al alloys are unclear, because the alloying elements included in Al alloys affect the structure of anodic oxide films. In the present study, porous anodic oxide films are formed on pure Al, 1050-, 3003- and 5052-Al alloys, and pore sealing was carried out in boiling water. Changes in the structure and corrosion protection ability of porous anodic oxide films on pure Al and the Al alloys by pore sealing, were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). SEM observation showed that anodic oxide films formed on pure Al have a smooth surface after pore sealing, and that cracks are formed in anodic oxide films on 1050-, 3003- and 5052-aluminum alloys, after pore sealing. Corrosion protection after pore sealing increased with anodizing time on pure Al, but only slightly increased with anodizing time on the Al alloys.

Globally, researchers have devoted consistent efforts to producing excellent coating properties since coating plays an essential role in enhancing electrochemical performance and surface quality. In this study, TiO2 nanoparticles in varying concentrations of 0.5, 1, 2, and 3 wt.% were added into the acrylic-epoxy polymeric matrix with 90:10 wt.% (90A:10E) ratio incorporated with 1 wt.% graphene, to fabricate graphene/TiO2 -based nanocomposite coating systems. Furthermore, the properties of the graphene/TiO2 composites were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), ultraviolet-visible (UV-Vis) spectroscopy, water contact angle (WCA) measurements, and cross-hatch test (CHT), respectively. Moreover, the field emission scanning electron microscope (FESEM) and the electrochemical impedance spectroscopy (EIS) tests were conducted to investigate the dispersibility and anticorrosion mechanism of the coatings. The EIS was observed by determining the breakpoint frequencies over a period of 90 days. The results revealed that the TiO2 nanoparticles were successfully decorated on the graphene surface by chemical bonds, which resulted in the graphene/TiO2 nanocomposite coatings exhibiting better dispersibility within the polymeric matrix. The WCA of the graphene/TiO2 coating increased along with the ratio of TiO2 to graphene, achieving the highest CA of 120.85° for 3 wt.% of TiO2. Excellent dispersion and uniform distribution of the TiO2 nanoparticles within the polymer matrix were shown up to 2 wt.% of TiO2 inclusion. Among the coating systems, throughout the immersion time, the graphene/TiO2 (1:1) coating system exhibited the best dispersibility and high impedance modulus values (Z0.01 Hz), exceeding 1010 Ω cm2.

Faradaic electrochemical impedance spectroscopy (f-EIS) in the presence of redox reagent, e.g., [Fe(CN)6]3−/4−, is widely used in biosensors owing to its high sensitivity. However, in sensors detecting amyloid beta (Aβ), the redox reagent can cause the aggregation of Aβ, which is a disturbance factor in accurate detection. Here, we propose an interdigitated microelectrode (IME) based f-EIS technique that can alleviate the aggregation of Aβ and achieve high sensitivity by buffer control. The proposed method was verified by analyzing three different EIS-based sensors: non-faradaic EIS (nf-EIS), f-EIS, and the proposed f-EIS with buffer control. We analyzed the equivalent circuits of nf-EIS and f-EIS sensors. The dominant factors of sensitivity were analyzed, and the impedance change rates via Aβ reaction was compared. We measured the sensitivity of the IME sensors based on nf-EIS, f-EIS, and the proposed f-EIS. The results demonstrate that the proposed EIS-based IME sensor can detect Aβ with a sensitivity of 7.40-fold and 10.93-fold higher than the nf-EIS and the f-EIS sensors, respectively.