Potential drops due to an attached bubble on a gas-evolving electrode

Abstract

It is shown how the various components of the overpotential due to an attached bubble on an electrode can be separated and estimated. By considering the resistance increments due to the presence on the electrode surface of a bubble, obtained from impedance measurements, it is possible to determine the predominant potential distribution which controls the gas evolution. A relationship between the measured overpotential and the diameter of the bubble is established. The time evolution of the overpotential due to a growing bubble is modelled in the case of the limitation of the bubble growth by dissolved gas diffusion in the solution. In agreement with previous experimental results a linear time variation is found.

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

“…1. The steep potential jumps are related to the detachment of bubbles from the electrode, whereas the linear potential increase is due to the bubble growth, as shown in [9] from a theoretical calculation when there are a few bubbles on the electrode and when their growth is controlled by dissolved molecular gas diffusion. We must insist upon the fact that this linear potential increase is due to the growth of all the bubbles on the electrode, i.e.…”

“…In a previous paper [9] it has been shown that under current control the overpotential fluctuations, Aqohm and At/a, can be written in terms of resistance fluctuations At/ohm(t ) -----ARe(t)I (5) At/,(t) ---ARp(t)I (6) where Iis the electrolysis current and ARe and Agp are the fluctuating parts of the electrolyte resistance, Re, and the polarization resistance (low frequency limit of the impedance), Rp, which reduces to the charge transfer resistance R t when the reaction mechanism of dissolved molecular gas production is a simple charge transfer reaction. The impedance variation induced by the presence on the electrode surface of an insulating sphere simulating a bubble has been measured for an iron disk electrode in sulphuric acid close to the corrosion potential.…”

“…In other experimental conditions these latter effects can be predominant [10,11]. The total overpotential fluctuation is now expressed by At/t(t ) = At/ohm(t ) -t-At/a(/)…”

A Mass Transfer Study with Electrolytic Gas Production

“…As presented by (Gabrielli et al,1989), the first correspond the transient step or the bubble´s radius variation with time and its depend of the electrolyte density. During the bubble growth the second step can be limited by diffusion of the dissolved molecular gas in the solution or by the kinetics of the production of the gas.…”

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.…”