Convolutive modeling of cyclic voltammetry, AC-voltammetry, sine wave voltammetry and impedance spectroscopy with interfacial CPE behaviour and uncompensated ohmic resistances: A Unified Theory

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.

An innovative experimental and mathematical approach in electrochemical sensing for mapping a drug sensor landscape

Our study delves into the examination of an electrochemical sensor through both experimentation and mathematical analysis. The sensor demonstrates the ability to identify a specific antipsychotic medication, namely Chlorpromazine Hydrochloride (CPH), even at incredibly low concentrations, reaching the picomolar level. The identification process relies on the utilization of a Glassy Carbon Electrode (GCE) that has been modified with a ceria-doped zirconia (CeO2/ZrO2) nanocomposite. The nanocomposite was synthesized using the co-precipitation technique and extensively characterized through various analytical methods. It is crucial to detect the presence of CPH as an overdose can result in hyperactivity and severe bipolar disorders among both children and adults. The average size of the nanocomposite was estimated to be 10 nm. The electrode surface area after CeO2/ZrO2 modification of the GCE was found to be 0.059 cm2, which was significantly higher than the electrode surface area of the bare GCE (0.0307 cm2). The limit of detection and limit of quantification for CPH were calculated to be 99.3 pM and 3.010 nM, respectively, with the linear dynamic range of CPH detection found to be between 0.10 and 1.90 μM. The modified sensor electrode was tested on human urine samples with good recoveries and exhibited high selectivity, repeatability, reproducibility, and long-term stability. The experimental voltammograms and the simulated stochastic voltammograms exhibited a fair amount of agreement. Examination of the experimental findings alongside analytical and numerical solutions enables a comprehensive analysis of the factors influencing the outcome of electrochemical measurements. The precise findings can be leveraged for the development of efficient sensing devices for medical diagnostics and environmental monitoring.

High Corrosion Resistance of a Ti-Based Anode with Sn/Ti/Nb Ternary Metal Oxide Interlayers

Ti-based anodes are widely applied in water splitting, the chlor-alkali industry, hydrometallurgy, and organic compound electrochemical synthesis. However, the thickening passivation layer in Ti substrates in acidic electrolytes accelerates the deactivation of whole Ti-based anodes. In order to block the attack from the reactive oxygen species, a compact interlayer containing ternary metal oxides (SnO₂, TiO₂, and Nb₂O₅, STN) on Ti foil (denoted as Ti-STN) was prepared via a facile thermal-decomposition method. The SnO₂, TiO₂, and Nb₂O₅ components impose the mutual restriction of grain growth during the pyrolytic synthetic progress, which promotes the grain refinement of STN interlayers. Due to the compact and stable STN interlayers, the Ti-STN substrate and the Ti-STN-derived active anodes presented an enhanced corrosion resistance and prolonged service lives. Hence, we believe that the Ti-STN substrate and the grain-refinement method to resist electrochemical corrosion in this work offer new approaches for the development of industrial electrolysis and electrochemical energy conversion devices.