Differential capacitance and electrochemical impedance study of surfactant adsorption on polycrystalline Ni electrode

Abstract

The adsorption of neutral organophosphorous compounds on a charged polycrystalline Ni electrode is studied by differential capacitance and impedance measurements in methanol solutions. Analysis of capacitance measurements reveals that tributylphosphine oxide, tri(n)octylphosphine oxide, and triphenylphosphine follow Langmuir adsorption isotherm. Saturation capacitance C sat , potential of maximum adsorption E max , limiting surface concentration Γ max , and standard Gibbs energy of adsorption ΔG max o at E max are determined. The cathodic reduction of (NiOCH 3 ) ads film formed on Ni surface at positive potentials, introducing a faradaic contribution in addition to the electrostatic charging of the interface, is supported by linear sweep voltammetric and impedance measurements. High values of electrode coverage and strong depression of faradaic currents are attained, indicating that these adsorbates may be suitable as corrosion inhibitors.

Bifunctional Redox Mediator Supported by an Anionic Surfactant for Long-Cycle Li–O2 Batteries

“…As illustrated in Figure 4c, with increasing concentrations of SDS below its critical micelle concentration (CMC), the capacitance of the double electric layer is lower, which means the adsorbance of the surfactant SDS is higher. 51 Moreover, the potential at minimum capacitance means charge neutralization on the electrode surface, often called a PZC. 35,52 Therefore, the adsorption layer of SDS made a PZC shift to the positive direction, as illustrated, and the maximum of PZC is located at 3.6 V, close to the redox potential of PTIO when the concentration of SDS is up to 5 mM.…”

Synthesis of Schiff‐base cationic Gemini surfactant and the properties for inhibiting corrosion of Q235 carbon steel and printed circuit board

“…It is well known that when the absolute value of Δ G ads is less than 20, the corrosion inhibitor is physically adsorbed to the metal surface, and when greater than 40, the corrosion inhibitor is chemically adsorbed to the metal surface (Abd El‐Lateef & Khalaf, 2021). Therefore, the Δ G ads value of TMPA denotes that the physical and chemical adsorption are both carried out simultaneously on the metal surface (Anastopoulos et al, 2015; Hernandez et al, 2019; Mandavian et al, 2018).…”

Redoxless Electrochemical Capacitance Spectroscopy for Investigating Surfactant Adsorption on Screen-Printed Carbon Electrodes

“…Redoxless ECS is a direct method for determining interfacial capacitance without the need for a redox couple or molecule immobilization on the electrode surfaces. Therefore, redoxless ECS complements label-free sensors such as QCM and surface plasmon resonance (SPR) in exploring the physicochemical characteristics of modified layers on electrodes [37,38].…”

“…Various electrochemistry methods, such as galvanostatic cycling, cyclic voltammetry, and EIS, investigate the effect of surfactants on the carbon electrode capacitance [36]. Polycrystalline Ni electrode adsorption was assessed using differential capacitance at a constant 80 Hz frequency [37]. The sensitivity and resolution of QCMs and ellipsometers were evaluated using the model of adsorption for small-molecule surfactants [38].…”