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Experimental Methods for Electrolyte
Published in Hualin Zhan, Graphene-Electrolyte Interfaces, 2020
As described in section 4.2, the charge transfer process between the electrode and electrolyte is enhanced significantly when the Fermi level of the electrode is close to the electrochemical potential of the electrolyte. The Fermi level can be tuned by applying a potential across the electrode-electrolyte interface. This potential can be applied by employing two electrodes (i.e., working electrode and counter electrode) in the electrolyte. However, due to the intrinsic redox potential of the material of the counter electrode, it is difficult to find the actual potential on the working electrode. Therefore, it is common to introduce an additional electrode with a fixed redox potential to the experimental setup. This electrode is called reference electrode, and such a system is defined as three-electrode electrochemical cell. An internationally accepted reference electrode is the Standard Hydrogen Electrode (or Normal Hydrogen Electrode) formed by blowing hydrogen gas to the platinum electrode in the electrolyte. Due to the convenience in electrode fabrication, another commonly used reference electrode is silver-silver chloride (Ag/AgCl) electrode [Bard and Faulkner (2000)].
Electrochemistry
Published in W. John Rankin, Chemical Thermodynamics, 2019
A common form of the hydrogen electrode is shown in Figure 16.5. By convention for aqueous solutions ΔfG0(H+,aq,a=1)=0 at all temperatures (Section 12.3), and since ΔG0=−zFE0 the potential of the hydrogen electrode at 1 bar and aH+=1 is 0 Volts at all temperatures. By combining a standard hydrogen electrode with another electrode to form a cell, the potential of the other electrode will be the voltage of the cell measured at zero current. This voltage is the standard electrode potential for the other half-cell reaction.
Flexible and Stretchable Energy Storage
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Each half cell potential can be deduced from reduction reactions that are obtained with respect to a standard hydrogen electrode (SHE). Nevertheless, potential values in real case examples deviate from the standard value and follow potential plateaus with respect to variations of ionic concentration. The potential dependence on ionic concentration (more accurately activity), temperature of the oxidized and reduced species is generally governed by the Nernst equation.
Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system
Published in Science and Technology of Advanced Materials, 2018
Andrei Ionut Mardare, Cezarina Cela Mardare, Jan Philipp Kollender, Silvia Huber, Achim Walter Hassel
The Hf–Nb–Ta library was mapped microstructurally and crystallographically before anodic oxide formation using scanning electron microscopy (SEM) and scanning X-ray diffraction (XRD), respectively. To this end, a field emission Zeiss (Oberkochen, Germany) Gemini 1540 XB SEM (with 20 kV acceleration voltage and in-lens detection) and a Philips (Almela, The Netherlands) X’pert Pro XRD system operated in grazing incidence mode (0.4° angle, Cu-Kα source) were used. Volta potential mapping of the parent metal alloys was performed by an in-house developed scanning Kelvin probe (SKP) system (employing a SKP measuring head from Wicinski-Wicinski GbR, Erkrath, Germany) built into a customised climate stabilisation chamber. The SKP probe material was a NiCr alloy with a tip diameter of 300 µm. The vibration frequency was approximately 1 kHz and the mean tip–sample distance was set to 75 µm. The relative humidity inside the climatic chamber was 11 ± 1%, and the ambient temperature was 22 ± 1 °C. Before mapping, the potential of the system was calibrated with saturated aqueous solution of CuSO4 in a Cu crucible. All potentials are relative to the standard hydrogen electrode (SHE).
Comparison of electrochemical behaviour between La-free and La-containing CrMnFeNi HEA by Mott–Schottky analysis and EIS measurements
Published in Corrosion Engineering, Science and Technology, 2021
Yipu Sun, Aidong Lan, Xi Jin, Huijun Yang, Junwei Qiao
All electrochemical experiments were performed in 0.5 M H2SO4 (pH: 0.6) aqueous solution, which was prepared from the deionised water and analytical grade reagent, using a classical three-electrode arrangement by a CHI660E electrochemical measurement system. A Mercury sulphate reference electrode (MSE) electrode was employed as the reference electrode, a Pt plate electrode was used as the counter electrode, and the samples is the working electrode. The experiments were repeated at least three times to ensure the reproducibility of the results. The data of potentials reported were calibrated to the standard hydrogen electrode (SHE).