Search results for "Standard hydrogen electrode"
showing 9 items of 9 documents
Identification of passive layers on Co in Alkaline solutions by photocurrent spectroscopy
2005
The photoelectrochemical behavior of passive films on Co has been studied as a function of the polarizing voltage and electrolyte composition. Passive layers formed at 0 V (standard hydrogen electrode, SHE) in 0.1 M NaOH consisted of Co(OH) 2 , whose bandgap value has been found to be 1.85 eV. Higher bandgap values (2.75 eV) have been measured for passive films formed in borate buffer at 0 V (SHE), which are mainly consist of CoO. The Eg values have been related to the film composition on the basis of a correlation between the bandgap of passive films and the electronegativity of their constituents.
Measurement of the Md3+/Md2+ Reduction Potential Studied with Flow Electrolytic Chromatography
2013
The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By application of the appropriate potentials on the chromatography column, the more stable Md(3+) is reduced to Md(2+). The reduction potential of the Md(3+) + e(-) → Md(2+) couple was determined to be -0.16 ± 0.05 V versus a normal hydrogen electrode.
Computational Screening of Doped Graphene Electrodes for Alkaline CO2 Reduction
2020
The electrocatalytic CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) is considered as one of the most promising approaches to synthesizing carbonaceous fuels and chemicals without utilizing fossil resources. However, current technologies are still in the early phase focusing primarily on identifying optimal electrode materials and reaction conditions. Doped graphene-based materials are among the best CO<sub>2</sub>RR electrocatalysts and in the present work we have performed a computational screening study to identify suitable graphene catalysts for CO<sub>2</sub>RR to CO under alkaline conditions. Several types of modified-graphene frame…
Electrolyses model development for metal/electrolyte interface: Testing with microrespiration sensors
2011
Abstract Initial process of electrolysis is investigated using platinum and tungsten wires as hydrogen electrodes and inductive kickback voltage peak based power unit. Microelectrodes are used to determine concentrations of dissolved hydrogen and pH close to wire electrodes. It is observed that concentration of dissolved hydrogen increases faster on tungsten electrode as on platinum. Authors explain this fact with differences of hydrogen evolution reaction on both materials – inductive kickback voltage peak power unit is supplying very short voltage pulses with limited energy what is enough only for hydrogen adsorption on platinum electrode, but is sufficient for full hydrogen evolution rea…
Redox potentials and acidity constants from density functional theory based molecular dynamics.
2014
CONSPECTUS: All-atom methods treat solute and solvent at the same level of electronic structure theory and statistical mechanics. All-atom computation of acidity constants (pKa) and redox potentials is still a challenge. In this Account, we review such a method combining density functional theory based molecular dynamics (DFTMD) and free energy perturbation (FEP) methods. The key computational tool is a FEP based method for reversible insertion of a proton or electron in a periodic DFTMD model system. The free energy of insertion (work function) is computed by thermodynamic integration of vertical energy gaps obtained from total energy differences. The problem of the loss of a physical refe…
Variation of the Fermi level and the electrostatic force of a metallic nanoparticle upon colliding with an electrode.
2017
When a metallic nanoparticle (NP) comes in close contact with an electrode, its Fermi level equilibrates with that of the electrode if their separation is less than the cut-off distance for electron tunnelling. In the absence of chemical reactions in solution, the charge on the metallic nanoparticle is constant outside this range before or after the collision. However, the double layer capacitances of both the electrode and the NP are influenced by each other, varying as the function of distance. Because the charge on the nanoparticle is constant, the outer potential of the metallic NP and hence its Fermi level varies as the capacitance changes. This effect is more pronounced for small part…
Studies of the Phosphatization of Steel and its Corrosion Products
1986
The reaction of phosphoric acid with steel is a basic process in many technological procedures. A typical example is the pretreatment of steel surfaces for the application of coatings. The aim of the treatment is to clean the surface, to produce a homogeneousr tight, and smooth cover and to provide a reliable adhesion between the steel substrate and the coating. This example points out that the phase composition of the layer formed is of great interest, and that reactions with residues on the surface, such as oxides and corrosion products, have to be considered, too. The same holds for phosphate layers formed in order to modify the mechanical or corrosion behavior of steel surfaces. Because…
The Formal Redox Potential of the Ti(IV, III) Couple at 25 °C in 1 M HCl 2 M NaCl Medium
2007
The formal redox potential of the Ti(IV, III) couple has been determined at 25 degrees C in 1 M HCl, 2 M NaCl aqueous medium, by emf measurements of a junction-free cell with glass and mercury electrodes. Ti(III) and Ti(IV) concentrations were changed by controlled electrolysis. The mean value of the searched formal potential, in a large range of total titanium concentration, is 9 +/- 1 mV against the molar hydrogen electrode in the same ionic medium.
The formal redox potential of the Yb(III,II) Couple at 0°C in 3.22 molal NaCl medium
2004
Following our previous investigations on aqueous solutions of hypooxidized and iperoxidized species, we managed, by lowering the temperature of the solutions to 0 degrees C, to obtain, by electrochemical methods, Yb(II) and Yb(III) mixtures, enough stable to determine by a potentiometric method the formal redox potential of the Yb(IlI, II) couple. Its value, in a large range of total Ytterbium concentration, is -1233 +/- 3 mV against the molal hydrogen electrode in the 3.22 m NaCl medium.