Electrochemical impedance spectroscopy (EIS) is a powerful technique used for the analysis of interfacial properties related to bio-recognition events occurring at the electrode surface, such as ...antibody–antigen recognition, substrate–enzyme interaction, or whole cell capturing. Thus, EIS could be exploited in several important biomedical diagnosis and environmental applications. However, the EIS is one of the most complex electrochemical methods, therefore, this review introduced the basic concepts and the theoretical background of the impedimetric technique along with the state of the art of the impedimetric biosensors and the impact of nanomaterials on the EIS performance. The use of nanomaterials such as nanoparticles, nanotubes, nanowires, and nanocomposites provided catalytic activity, enhanced sensing elements immobilization, promoted faster electron transfer, and increased reliability and accuracy of the reported EIS sensors. Thus, the EIS was used for the effective quantitative and qualitative detections of pathogens, DNA, cancer-associated biomarkers, etc. Through this review article, intensive literature review is provided to highlight the impact of nanomaterials on enhancing the analytical features of impedimetric biosensors.
•Evolution of the corrosion product layer was studied with EIS.•Initially the surface behaves as a plain corroding electrode gradually blocked by scales.•OCP rise characteristic of ...“pseudo-passivation” is concomitant with diffusion limitation.•High frequency time constant associated with the corrosion product film.
In the following research, electrochemical and surface analysis techniques are used to define the main contributing factor to the protectiveness offered by a scale formed at high temperature and pH under CO2 saturated conditions. At 80 °C and pH 6.6, trace amounts of a magnetite (Fe3O4) phase was identified at certain locations beneath a more dominant iron carbonate (FeCO3) film. Furthermore, over time, the evolution of the corrosion product layer towards a very low porosity results in a “diffusion barrier” that is indicated by a positive shift in the open circuit potential and is considered key to corrosion protection.
Targeted strategies to overcome defects in organic semiconductors require insight into their identity and origin. Here the formation, nature, and location of defects is studied in PM6:Y6 organic ...solar cells by sensitive EQE measurements. Exposure of the active layer to ambient atmosphere and H2O‐saturated compressed air indicates that a trace constituent in ambient air causes the formation of defects. By exposing the active layer to O3‐enriched air, O3 is identified as the species creating defects in PM6:Y6 blends. Aging of complete inverted (n–i–p) configuration solar cells in H2O‐saturated compressed air also increases the defect response. This is attributed to a reduced band bending at the PM6:Y6 | MoO3 hole‐collecting contact, caused by a change in work function of MoO3 interacting with the H2O, which allows more defect states to be filled and available for photoexcitation. By measuring energy resolved‐electrochemical impedance spectroscopy and by fabricating semitransparent cells, regular architecture cells, and semitransparent cells with an optical spacer−mirror stack it is found that defects originate predominantly from PM6 and are located near the top electrode, independent of device polarity. Because O3 is omnipresent in ambient atmosphere, albeit in small amounts, it likely causes defects in many organic semiconductors exposed to ambient air.
Sensitive external quantum efficiency measurements combined with energy resolved‐electrochemical impedance spectroscopy reveal that ozone, and not water or oxygen, in ambient air is the origin of sub‐bandgap defects that occur in polymer donor–non‐fullerene acceptor organic solar cells. The defects are primarily located at the top side of the film and arise due to degradation of the polymer donor.
Distribution of relaxation times (DRT) analysis is a powerful assistant tool for electrochemical impedance spectroscopy (EIS) deconvolution. In the present work, electrode degradation is evaluated by ...estimation of polarization resistances using DRT analysis. Five or six DRT peaks are detected for anode-supported microtubular solid oxide fuel cells (SOFCs) at 600–650 °C. In a reduction-oxidation (redox) cycling test, the polarization resistance of charge transfer and ionic conduction processes in the anode increases due to the decrease in triple phase boundary (TPB) length. On the other hand, initial electrode degradation is also successfully evaluated using DRT analysis during a galvanostatic test. The rapid growth of nickel grains in the anode and the relatively slow growth of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) grains in the cathode are observed after the test, which corresponds with the increase in the polarization resistance of charge transfer and ionic conduction processes in the anode and that of oxygen surface exchange and diffusion processes in the cathode, respectively.
State-of-health (SOH) is crucial to the maintenance of various kinds of energy storage systems, including power batteries. Relevant research articles are mostly based on battery external information, ...such as current, voltage, and temperature, which are susceptible to fluctuation and ultimately affects the SOH estimation accuracy. In this article, to solve these problems, a fast impedance calculation-based battery SOH estimation method for lithium-ion battery is proposed from the perspective of electrochemical impedance spectroscopy (EIS). The relationship between EIS and state of charge and that between EIS and degraded capacity is first studied by experimental tests. Some impedance features called health factors effectively indicating battery aging states are selected. Second, an improved fast Fourier transform (FFT) utilizing the conversion relationship between the real and complex signals is proposed to realize online fast EIS acquisition. Compared with ordinary FFT, such treatments reduce computational complexity. Then, the SOH evaluation model is built by the extreme learning machine with regularization mechanism, further reducing the computational burden. The relationship between the health factors and aging capacity of batteries is established. Finally, an experimental bench is established. The results indicate that the estimated SOH can be obtained within 35 s for a four-cell series-connected battery pack and the estimation errors are less than 2%.
Present investigation deals with electrochemical determination of copper(II), lead(II) and mercury(II) ions, using ethylenediaminetetraacetic acid (EDTA) chelating ligand modified polyaniline (PANI) ...and singe walled carbon nanotubes (SWCNTs) based nanocomposite (PANI/SWNCTs). Stainless steel (SS) electrode was modified with PANI and SWCNTs based nanocomposite. PANI/SWCNTs nanocomposite was electrochemically synthesized using potential cycling technique. Further it was modified with EDTA in the presence of 1-ethyl-3(3-(dimethylamin propyl)carbodiimide (EDC) as activating agent, using dip coating technique at room temperature. The EDTA_PANI/SWCNTs/SS electrode was characterized by cyclic voltammetry in 0.5 M H2SO4, which was complemented with electrochemical impedance spectroscopy (EIS). AFM and SEM analysis was applied for the morphological studies of EDTA_PANI/SWCNTs nanocomposite structure. FTIR analysis was applied for the structural and compositional analysis of EDTA_PANI/SWCNTs nanocomposite. All the characterizations were performed before and after the modification of PANI/SWCNTs nanocomposite structure with chelating ligand. Differential pulse voltammetry (DPV) was used for the determination of Cu(II), Pb(II) and Hg(II) ion concentrations. Analytical characteristic such as selectivity and sensitivity of here above-mentioned metal ions was studied. The limit of detection the EDTA_PANI/SWCNTs/SS toward Cu(II), Pb(II) and Hg(II) was determined as 0.08 μM, 1.65 μM and 0.68 μM respectively.
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Electrochemical energy storage is critical for a range of applications spanning electrified transportation and grid energy storage, and there is a need to further improve both the active management ...and diagnostic capability of current battery management systems. Lithium-based battery chemistries have been favored for their high energy and power densities but require precise management to prevent premature degradation and failure. This work presents an efficient power converter (based on a switched-inductor ladder topology), instrumentation, and an embedded control platform that can provide both active balancing and real-time diagnostic capability through electrochemical impedance spectroscopy (EIS). A digital proportional-integral controller enforces sinusoidal reference signals from a direct digital synthesizer, enabling the power converter to perturb the cells and extract their impedance. Cell-level diagnostics allow for noninvasive measurement of physical electrochemical battery properties that can be used to assess the state of charge and state of health of a battery. A ladder converter prototype was implemented on a printed circuit board to perform EIS on two Panasonic 18650 cells in series. Experimental results showed balancing converter efficiency of 95%, and the accuracy of the prototype was validated through comparison to a state-of-the-art commercial benchtop system.
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