Investigation of water electrolysis by spectral analysis. I. Influence of the current density

Abstract

The potential (or current) fluctuations observed under current (or potential) control during gas evolution were analysed by spectral analysis. The power spectral densities (psd) of these fluctuations were measured for hydrogen and oxygen evolution in acid and alkaline solutions at a platinum disk electrode of small diameter. Using a theoretical model, some parameters of the gas evolution were derived from the measured psd of the potential fluctuations, such as the average number of detached bubbles per time unit, the average radius of the detached bubbles and the gas evolution efficiency. The influence of the electrolysis current on these parameters was also investigated. The results of this first attempt at parameter derivation are discussed.

In-situ particle sizing at millimeter scale from electrochemical noise: simulation and experiments

“…Indeed, the presence of discrete entities (gas bubbles, oil droplets, solid particles…) near a working electrode generates fluctuations of current, potential, and also fluctuations of the electrolyte resistance (ER) between the reference electrode and the working electrode that are provoked by changes in the current distribution (screening effects) [21][22][23][24][25]. The analysis of the EN signals in both time and frequency domains allows a more precise identification of the elementary events at the origin of noise, which is not possible with classical electrochemical methods, such as impedance spectroscopy or cyclic voltammetry, that give information averaged in time and over the electrode surface.…”

“…The analysis of the EN signals in both time and frequency domains allows a more precise identification of the elementary events at the origin of noise, which is not possible with classical electrochemical methods, such as impedance spectroscopy or cyclic voltammetry, that give information averaged in time and over the electrode surface. This technique has been successfully applied to determine the size and departure rate of bubbles on a gas-evolving electrode [21][22], to determine the electrical charge exchanges between conductive beads and a current collector [23], to get a detailed view of the approach and residence of microcapsules close to the electrode during composite plating [24], or to characterize the composition of oil-brine mixtures in a flow-loop cell [25].…”

Influence of magnetic field on hydrogen reduction and co-reduction in the Cu/CuSO4 system

“…In particular, low-frequency noise varying with frequency f as 1/f 2 , was reported by Gabrielli and coworkers [16][17][18][19]. A model, treating bubbles departures as a sequence of random events, was used to explain the observed spectrum, and could reproduce some of these features [19].…”

“…In particular, low-frequency noise varying with frequency f as 1/f 2 , was reported by Gabrielli and coworkers [16][17][18][19]. A model, treating bubbles departures as a sequence of random events, was used to explain the observed spectrum, and could reproduce some of these features [19]. Steyer et al explained that the 1/f 2 noise spectrum is characteristic of a coalescence phenomenon [20], where an assembly of gas droplets grow on a substrate and coalesce when they touch according to the mass conservation rule.…”

Manipulating surface nanobubbles

“…Most studies have hitherto focused on mini-or micrometer sized bubbles, which are formed at and subsequently detach from the electrodes; see [20][21][22][23][24][25] and references therein. The formation of hydrogen microbubbles on a negative electrode has been witnessed by phase-contrast (a) 300 µm Figure 5.1: Phase-contrast microradiograph revealing the generation of micrometer sized hydrogen bubbles on an electrode that acts as cathode.…”