Electrochemical Oscillations Research Articles

Nanostructured bismuth phosphate-based asymmetric supercapacitor: electrochemical evaluation and oscillator application

Phosphate-based materials have received significant attention for various applications. In supercapacitors, metal phosphates exhibit high capacitance and superior rate performance. In this work, a wet chemical route was applied for the fabrication of aniline stabilized monoclinic bismuth phosphate (BPO) particles within the size range of 4–10 nm. The synthesized material was utilized as an active component for the application of a supercapacitor. The performances of the material were examined on a nickel foam for a three-electrode electrochemical cell. The material showed the maximum specific capacitance (CSP\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{SP}$$\\end{document}) value of 255 F.g−1 at the current density (CD) of 2 A.g−1. Further, an asymmetric supercapacitor (ASC) device was fabricated with BPO and single wall carbon nanotube (SWCNT) as negative and positive electrodes, respectively, which delivered a specific capacity (Qs)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(Qs)$$\\end{document} value of 1462 mAh.g−1 under the CD of 0.4 A.g−1 with the energy density (ED) and power density (PD) values of 2.2 Wh.kg−1 and 0.68 kW.kg−1, respectively. The device exhibited capacity retention and coulombic efficiency (CE) values of 84 and 95% at 0.9 A.g−1 for 10,000 galvanostatic charge–discharge (GCD) cycles. The ASC device generated a low-frequency waveform and has the potential to function as an oscillator.

Strong coupling yields abrupt synchronization transitions in coupled oscillators

Coupled oscillator networks often display transitions between qualitatively different phase-locked solutions—such as synchrony and rotating wave solutions—following perturbation or parameter variation. In the limit of weak coupling, these transitions can be understood in terms of commonly studied phase approximations. As the coupling strength increases, however, predicting the location and criticality of transition, whether continuous or discontinuous, from the phase dynamics may depend on the order of the phase approximation—or a phase description of the network dynamics that neglects amplitudes may become impossible altogether. Here we analyze synchronization transitions and their criticality systematically for varying coupling strength in theory and experiments with coupled electrochemical oscillators. First, we analyze bifurcations analysis of synchrony and splay states in an abstract phase model and discuss conditions under which synchronization transitions with different criticalities are possible. In particular, we show that such conditions can be understood by considering the relative contributions of higher harmonics to the phase dynamics. Second, we illustrate that transitions with different criticality indeed occur in experimental systems. Third, we highlight that the amplitude dynamics observed in the experiments can be captured in a numerical bifurcation analysis of delay-coupled oscillators. Our results showcase that reduced order phase models may miss important features that one would expect in the dynamics of the full system. Published by the American Physical Society 2024

Optimal phase-selective entrainment of electrochemical oscillators with different phase response curves.

We investigate the entrainment of electrochemical oscillators with different phase response curves (PRCs) using a global signal: the goal is to achieve the desired phase configuration using a minimum-power waveform. Establishing the desired phase relationships in a highly nonlinear networked system exhibiting significant heterogeneities, such as different conditions or parameters for the oscillators, presents a considerable challenge because different units respond differently to the common global entraining signal. In this work, we apply an optimal phase-selective entrainment technique in both a kinetic model and experiments involving electrochemical oscillators in achieving phase synchronized states. We estimate the PRCs of the oscillators at different circuit potentials and external resistance, and entrain pairs and small sets of four oscillators in various phase configurations. We show that for small PRC variations, phase assignment can be achieved using an averaged PRC in the control design. However, when the PRCs are sufficiently different, individual PRCs are needed to entrain the system with the expected phase relationships. The results show that oscillator assemblies with heterogeneous PRCs can be effectively entrained to desired phase configurations in practical settings. These findings open new avenues to applications in biological and engineered oscillator systems where synchronization patterns are essential for system performance.

Synchronization of two electrochemical oscillators in a closed bipolar cell

Synchronization of two electrochemical oscillators in a closed bipolar cell

Electrochemical oscillation behaviors of gold during its recovery from waste printed circuit boards through slurry electrolysis

Slurry electrolysis is an effective technology for recovering gold from waste printed circuit boards (WPCBs). However, electrochemical oscillation during the gold recovery process is a potential factor affecting power consumption. As a result, the potential oscillation behaviors of gold dissolution at a constant current were studied. These results showed that the periodic formation and dissolution of the Au-OH passive film on the anode induced electrochemical oscillation. The amplitude and frequency of electrochemical oscillation were affected by hydrochloric acid concentration, current intensity, electrode spacing, and sodium chloride concentration, among which the concentration of sodium chloride had a significant inhibitory effect. Under the following conditions: hydrochloric acid concentration of 8 mol/L, current of 0.03 A, and electrode spacing of 1.5 cm, the obtained maximum amplitude potential and frequency were 1.17 V and 0.56 Hz, respectively. The phase space reconstruction results showed that the systems evolved between the near-linear equilibrium region and the periodic oscillation region. Different factors induced two oscillation modes: top-down and bottom-up. The top-down and bottom-up oscillations induced by current intensity, hydrochloric acid concentration, and electrode spacing reduced the relative power consumption by 11.8, 17.2, and 11.8 %, respectively, and increased the relative power consumption by 14.3, 21.2, and 30.1 %, respectively. A critical value was obtained, which varied oscillation patterns and gained a region of lower power consumption. The addition of trisodium citrate and PVP can improve gold recovery rate and current efficiency by regulating process of electrochemical oscillation. This work will provide theoretical support for recovering valuable metals from WPCBs with reduced energy consumption by controlling the external conditions to switch the oscillation mode.

Quality control and evaluation of Black chokeberry (Aronia melanocarpa) by three-wavelength fusion fingerprinting and electrochemical fingerprinting combined with antioxidant activity analysis

In this study, Black chokeberry (Aronia melanocarpa) was used as an example to provide reference for improving the safety, efficacy and quality consistency of homologous foods. In this study, two quality markers (Q-markers) of 27 batches of Black chokeberry were determined using high performance liquid chromatography (HPLC), and there were some differences among the 27 samples. Origin B samples had the highest levels of Q-markers for S15, and origin C had lower than average levels overall. Samples were analyzed qualitatively and quantitatively by Systematic Quantitative Fingerprinting (SQFM). Subsequently, a three-wavelength fusion analysis (TWFP) was established on the chromatographic data to compensate for the lack of a single wavelength. Fourteen batches of TWFP samples were rated at Level 5 or above in the SQFM assessment, indicating that there is some variation in the content of samples from different origins. Principal component analysis (PCA) was used to observe the differences in chemical composition and content of TWFP samples. Subsequently, electrochemical fingerprinting (ECFP) was established and nine characteristic parameters were recorded, showing that the samples were suppressed for all electrochemical Belousov-Zhabotinsky oscillation systems (B-Z oscillation systems). Finally, antioxidant tests were performed using DPPH. The antioxidant capacity was predicted using Partial Least Squares (PLS) analysis with R2Y = 0.84, Q2 = 0.77, a good model fit and accurate prediction. The fingerprint-potency relationship between IC50-peak area showed that 17 of the 19 shared peaks were negatively correlated, indicating that 17 peaks contributed significantly to the antioxidant. The methods established in this study for the determination of TWFP and ECFP, as well as the spectral relationships with peak area and IC50, can be used for the quality inspection and antioxidant capacity test of Black chokeberry, which provides a new research direction for improving the quality standard of medicinal and foodstuffs.

Hyperchaotic power with wide current variation for efficient manganese electrodeposition

A practical hyperchaotic circuit has been designed, which has further been successfully applied to the manganese metal electrolysis system, replacing the traditional direct current power to alter the dynamic system of electrolysis process. The results illustrate that the hyperchaotic current can significantly suppress the electrochemical oscillation. Therefore, the growth of manganese (Mn) dendrites in the cathode can be significantly suppressed by the ultra − wide chaotic current fluctuation because of the regulation of electronic dynamic system. In addition, the distribution of manganese dendrites is quantified for the first time through image analysis, processing, and calculation. Besides, the hyperchaotic current can also considerably improve the current efficiency with 2 % increasing and reduce the energy consumption about 0.3 kW·h/kg simultaneously. It also demonstrates some advantages of chaotic current electrodeposition technology by conducting a larger-scale chaotic current electrolysis experiment.

Electrolyte design for the manipulation of gas bubble detachment during hydrogen evolution reaction

During electrochemical gas evolution reactions, the continuous and vigorous formation of gas bubbles hugely impacts the efficiency of the underlying electrochemical processes. In particular, enhancing the detachment of gas bubbles from the electrode surface has emerged as an effective strategy to improve reaction efficiency. In this study, we demonstrate that the detachment of H2 gas bubbles can be controlled by the electrolyte composition, which can be optimized. We employ a well-defined Pt microelectrode and utilize electrochemical oscillation analysis to elucidate the features of H2 gas bubble detachment. Our investigation explores how the behaviour of H2 gas bubbles responds to variations in electrolyte composition and concentration. The coalescence efficiency of electrochemically generated microbubbles, a critical factor determining the mode of H2 gas bubble detachment (random detachment vs. single H2 gas bubble detachment), is profoundly influenced by the electrolyte composition. Specifically, coalescence efficiency follows the Hofmeister series concerning anions and coalescence is consistently inhibited in the presence of alkali metal cations. Furthermore, we establish a comprehensive model that accounts for both thermal and solutal Marangoni effects, allowing us to rationalize the trend of detachment size and period of single H2 gas bubbles under various conditions.

Electrochemical oscillation during galvanostatic charging and discharging of Zr-modified Li4Ti5O12 in Li-ion batteries.

The electrochemical oscillation in Li-ion batteries has been reported for two-phase electrode materials of Li4Ti5O12 and LiCrTiO4, which is originated from the group-by-group phase transition in a multi-particle electrode. For both Li4Ti5O12 and LiCrTiO4, the electrochemical oscillation exhibits usually during charging, while rarely for discharging. Herein, a series of Zr-modified Li4Ti5O12 samples are prepared by using the spray-drying combined with high-temperature sintering method, and the electrochemical oscillation is observed during not only the charging process, but also the discharging process, which gradually grows up and then disappears by increasing the Li content. Compared with Li4Ti5O12, the specific capacity of Zr-modified Li4Ti5O12 decreases gradually by increasing the Zr/Ti ratio, owing to the impurity phases. According to the XRD, XPS and STEM results, the Zr element tends to accumulate on the surface to form ZrO2 nanoparticles, rather than dope into the bulk phase of Li4Ti5O12, which makes Li4Ti5O12 particles well dispersive. In contrast to the Li deficiency for only charging, the electrochemical oscillation during both charging and discharging should be attributed to the Li excess, but too much Li2TiO3 phase will suppress the electrochemical oscillation. Therefore, the Li excess can induce the electrochemical oscillation during both charging and discharging of Zr-modified Li4Ti5O12, which can be adopted to investigate the electrochemical oscillation of other materials in LIBs.

A New Approach of Electrolytic Metal Manganese with Lower Energy Consumption and Fewer Spherical Dendrites Based on a Hyperchaotic Circuit with Directly Offset Boosting

Electrolysis is an important way to produce manganese metal, but the low current efficiency and random growth of dendrites have always been challenging problems for enterprises. The lack of understanding of the dynamic system during the electrolysis process is the main reason for the accurate control of the electrolysis process. Based on this consideration, a new four-dimensional continuous hyperchaotic system with high Lyapunov exponents is designed. The amplitude control, frequency modulation, and offset boosting of the hyperchaotic system are obtained through the selection of feedback term. A circuit simulation and corresponding simplified circuit are established. In addition, the actual hyperchaotic circuit is applied to the manganese electrolysis process through the self-designed current amplification module (the amplification of [Formula: see text] signal is realized by the offset boosting control). The experimental results of the hyperchaotic electrolysis of metal manganese showed that the hyperchaotic current can delay the occurrence time of electrochemical oscillation, and reduce the generation of cathode metal manganese dendrites. Furthermore, the results show that the hyperchaotic current can enhance the current efficiency and reduce the energy consumption. Based on the new experiment, it is suggested that the formation of anodic porous structures, whose primary phase compositions were PbSO4, MnO2, and Mn2O3, is one factor for the occurrence of electrochemical oscillations, while the conversion between Mn[Formula: see text] and Mn[Formula: see text] is another main factor for the mutation of electrochemical signal (manganese autocatalysis).

A dual-clock-driven model of lymphatic muscle cell pacemaking to emulate knock-out of Ano1 or IP3R.

Lymphatic system defects are involved in a wide range of diseases, including obesity, cardiovascular disease, and neurological disorders, such as Alzheimer's disease. Fluid return through the lymphatic vascular system is primarily provided by contractions of muscle cells in the walls of lymphatic vessels, which are in turn driven by electrochemical oscillations that cause rhythmic action potentials and associated surges in intracellular calcium ion concentration. There is an incomplete understanding of the mechanisms involved in these repeated events, restricting the development of pharmacological treatments for dysfunction. Previously, we proposed a model where autonomous oscillations in the membrane potential (M-clock) drove passive oscillations in the calcium concentration (C-clock). In this paper, to model more accurately what is known about the underlying physiology, we extend this model to the case where the M-clock and the C-clock oscillators are both active but coupled together, thus both driving the action potentials. This extension results from modifications to the model's description of the IP3 receptor, a key C-clock mechanism. The synchronised dual-driving clock behaviour enables the model to match IP3 receptor knock-out data, thus resolving an issue with previous models. We also use phase-plane analysis to explain the mechanisms of coupling of the dual clocks. The model has the potential to help determine mechanisms and find targets for pharmacological treatment of some causes of lymphoedema.

Finding influential nodes in networks using pinning control: Centrality measures confirmed with electrochemical oscillators.

The spatiotemporal organization of networks of dynamical units can break down resulting in diseases (e.g., in the brain) or large-scale malfunctions (e.g., power grid blackouts). Re-establishment of function then requires identification of the optimal intervention site from which the network behavior is most efficiently re-stabilized. Here, we consider one such scenario with a network of units with oscillatory dynamics, which can be suppressed by sufficiently strong coupling and stabilizing a single unit, i.e., pinning control. We analyze the stability of the network with hyperbolas in the control gain vs coupling strength state space and identify the most influential node (MIN) as the node that requires the weakest coupling to stabilize the network in the limit of very strong control gain. A computationally efficient method, based on the Moore-Penrose pseudoinverse of the network Laplacian matrix, was found to be efficient in identifying the MIN. In addition, we have found that in some networks, the MIN relocates when the control gain is changed, and thus, different nodes are the most influential ones for weakly and strongly coupled networks. A control theoretic measure is proposed to identify networks with unique or relocating MINs. We have identified real-world networks with relocating MINs, such as social and power grid networks. The results were confirmed in experiments with networks of chemical reactions, where oscillations in the networks were effectively suppressed through the pinning of a single reaction site determined by the computational method.

Transitional cluster dynamics in a model for delay-coupled chemical oscillators.

Cluster synchronization is a fundamental phenomenon in systems of coupled oscillators. Here, we investigate clustering patterns that emerge in a unidirectional ring of four delay-coupled electrochemical oscillators. A voltage parameter in the experimental setup controls the onset of oscillations via a Hopf bifurcation. For a smaller voltage, the oscillators exhibit simple, so-called primary, clustering patterns, where all phase differences between each set of coupled oscillators are identical. However, upon increasing the voltage, secondary states, where phase differences differ, are detected, in addition to the primary states. Previous work on this system saw the development of a mathematical model that explained how the existence, stability, and common frequency of the experimentally observed cluster states could be accurately controlled by the delay time of the coupling. In this study, we revisit the mathematical model of the electrochemical oscillators in order to address open questions by means of bifurcation analysis. Our analysis reveals how the stable cluster states, corresponding to experimental observations, lose their stability via an assortment of bifurcation types. The analysis further reveals complex interconnectedness between branches of different cluster types. We find that each secondary state provides a continuous transition between certain primary states. These connections are explained by studying the phase space and parameter symmetries of the respective states. Furthermore, we show that it is only for a larger value of the voltage parameter that the branches of secondary states develop intervals of stability. For a smaller voltage, all the branches of secondary states are completely unstable and are, therefore, hidden to experimentalists.

The theoretical description for omeprazole electrochemical determination, assisted by the composite poly(1,2,4-triazole)-Ag2O2

Introduction: Omeprazole is one of the most used proton-blocking molecules applied in the gastric ulcer treatment. Its blocking effect is achieved by the presence of both acidic and basic nitrogen heteroatoms in its composition. Nevertheless, due to its collateral effects, which may be moderate to severe, the development of its electrochemical determination is really actual. Methods: In this work, we describe theoretically the possibility of omeprazole electrochemical determination, assisted by the composite, containing the silver (I, III) oxide as an active substance and the polymer of 1,2,4-triazolic derivative as a mediator. In this case, the omeprazole molecule is gradually oxidized yielding firstly phenolic and then quinonic derivative. The pyridinic nitrogen is oxidized later. Results: The electroanalytical process is described by a trivariant equation-set, analysis of which confirms the efficiency of the composite of poly(1,2,4-triazole) with Ag2O2. The electrochemical oscillations are also possible, being realized beyond the detection limit. Conclusion: The composite of poly(1,2,4-triazole) with Ag2O is suitable for omeprazole electrochemical determination both in vivo and in vitro.

Slow Manifolds for Stochastic Koper Models with Stable Lévy Noises

The Koper model is a vector field in which the differential equations describe the electrochemical oscillations appearing in diffusion processes. This work focuses on the understanding of the slow dynamics of a stochastic Koper model perturbed by stable Lévy noise. We establish the slow manifold for a stochastic Koper model with stable Lévy noise and verify exponential tracking properties. We also present two practical examples to demonstrate the analytical results with numerical simulations.

Quenching of oscillations via attenuated coupling for dissimilar electrochemical systems.

The coupled dynamics of two similar and disparate electrochemical cells oscillators are analyzed. For the similar case, the cells are intentionally operated at different system parameters such that they exhibit distinct oscillatory dynamics ranging from periodic to chaotic. It is observed that when such systems are subjected to an attenuated coupling, implemented bidirectionally, they undergo a mutual quenching of oscillations. The same holds true for the configuration wherein two entirely different electrochemical cells are coupled via bidirectional attenuated coupling. Therefore, the attenuated coupling protocol seems to be universally efficient in achieving oscillation suppression in coupled oscillators (similar or heterogeneous oscillators). The experimental observations were verified by numerical simulations using appropriate electrodissolution model systems. Our results indicate that quenching of oscillations via attenuated coupling is robust and therefore could be ubiquitous in coupled systems with a large spatial separation prone to transmission losses.

An organic artificial spiking neuron for in situ neuromorphic sensing and biointerfacing

The effective mimicry of neurons is key to the development of neuromorphic electronics. However, artificial neurons are not typically capable of operating in biological environments, which limits their ability to interface with biological components and to offer realistic neuronal emulation. Organic artificial neurons based on conventional circuit oscillators have been created, but they require many elements for their implementation. Here we report an organic artificial neuron that is based on a compact nonlinear electrochemical element. The artificial neuron can operate in a liquid and is sensitive to the concentration of biological species (such as dopamine or ions) in its surroundings. The system offers in situ operation and spiking behaviour in biologically relevant environments—including typical physiological and pathological concentration ranges (5–150 mM)—and with ion specificity. Small-amplitude (1–150 mV) electrochemical oscillations and noise in the electrolytic medium shape the neuronal dynamics, whereas changes in ionic (≥2% over the physiological baseline) and biomolecular (≥ 0.1 mM dopamine) concentrations modulate the neuronal excitability. We also create biohybrid interfaces in which an artificial neuron functions synergistically and in real time with epithelial cell biological membranes.

The Theoretical Description for Amavadin-Ion Electrochemical Determination in Amanita muscaria Mushroom Pulp and Extract by Galvanostatic Conducting Polymer Doping

The theoretical description for amavadin-ion electrochemical determination in mushroom pulp has been given for the first time. The correspondent mathematical model has been developed and analyzed by linear stability theory and bifurcation analysis, providing the theoretical investigation of the electrochemical behavior of the electroanalytical system. It has been shown that the system behavior in galvanostatic mode is more dynamic than in potentiostatic mode, which is reflected in the enhancement of the probability of the electrochemical oscillations due to the intense influence of chemical and electrochemical stages on both DEL and surface charge. Nevertheless, the system is efficient for electroanalysis or conducting polymer modification for electroanalytical purposes.

High performance liquid chromatography three-wavelength fusion fingerprint combined with electrochemical fingerprint and antioxidant method to evaluate the quality consistency of Mingmu Dihuang Pill

In this paper, three-wavelength fusion fingerprint (TWFFP) combined with electrochemical fingerprint (ECFP) and antioxidant methods were used to jointly explore the quality consistency of Mingmu Dihuang Pill (MMDHP). The TWFFP fully demonstrated the maximum ultraviolet absorption characteristics at multiple wavelengths, supplemented the defects brought by the single-wavelength evaluation. ECFP was established to analyze the characteristic parameters in more depth, and all samples had inhibitory effects on the electrochemical oscillation system. Using 2,2-diaza-bis(3-ethylbenzothiazole-6-sulfonic acid) antioxidant test, combined with ECFP, the fingerprint-efficacy relationship was established with the peak areas of the TWFFP. As a result, 15 of the 36 common peaks made important contributions to both efficacy relationships at the same time. The TWFFP and ECFP were evaluated by a systematically quantified fingerprint method, and the ability of HPLC and electrochemical to distinguish samples was discussed by hierarchical clustering analysis. Content percentage was introduced to calculate the relationship between marker components and macro quantitative similarity. The method of quantitative analysis of multi-components by single marker was explored to analyze the accuracy of evaluating the marker components. This study provided a comprehensive and reliable method for the quality consistency control of complex Traditional Chinese Medicine and its compound preparations.

Emergent hypernetworks in weakly coupled oscillators

Networks of weakly coupled oscillators had a profound impact on our understanding of complex systems. Studies on model reconstruction from data have shown prevalent contributions from hypernetworks with triplet and higher interactions among oscillators, in spite that such models were originally defined as oscillator networks with pairwise interactions. Here, we show that hypernetworks can spontaneously emerge even in the presence of pairwise albeit nonlinear coupling given certain triplet frequency resonance conditions. The results are demonstrated in experiments with electrochemical oscillators and in simulations with integrate-and-fire neurons. By developing a comprehensive theory, we uncover the mechanism for emergent hypernetworks by identifying appearing and forbidden frequency resonant conditions. Furthermore, it is shown that microscopic linear (difference) coupling among units results in coupled mean fields, which have sufficient nonlinearity to facilitate hypernetworks. Our findings shed light on the apparent abundance of hypernetworks and provide a constructive way to predict and engineer their emergence.