An experimental investigation of periodic and chaotic electrochemical oscillations in the anodic dissolution of copper in phosphoric acid

Abstract

The response of the current to an applied potential was monitored in an open electrochemical system consisting of a rotating copper disk as the working electrode, a calomel reference electrode, and a platinum counter electrode, all of which were in contact with a solution of 85% phosphoric acid. In addition to stable stationary states, the applied potential induced oscillatory states which were either periodic or chaotic. Transitions from a stationary state to sustained oscillations were found to take place either through a Hopf bifurcation or by way of a mechanism that gives rise to states possessing complex combinations of small and large amplitude oscillations (mixed-mode oscillations). Within the parameter ranges for which sustained oscillations occurred, we discovered sequences of period doubling bifurcations. Aperiodic oscillations were observed just beyond the limit at which a sequence terminated. Phase trajectories were constructed from time-series data for these aperiodic states from which we produced one-humped, one-dimensional maps. A trajectory was also constructed that closely resembled a homoclinic orbit. Mixed-mode oscillations were found which have the same properties as those previously observed in the Belousov–Zhabotinskii reaction. The production of copper was observed in this electrochemical system which suggests that the reaction of disproportionality may be part of a feedback mechanism that is responsible for the complex dynamical behavior.

Temporal Instabilities in Corrosion Processes

“…Among more recent reports, works by Glarum and Marshall [63,64], systematic investigations performed by Albahadily and Schell [65][66][67], and selected works of other researchers deserve a brief description here. In contrast to the Fe/H 2 SO 4 system, the anodic potentiodynamic voltammograms of Cu dissolution in 85% phosphoric acid, studied at the rotating Cu disk electrode, do not exhibit clear transition from the active to passive region, and in spite of that the current oscillations occur at the quasi-plateau of the anodic current (Fig.…”

Electrochemical Studies with Copper‐Based Alloys: Open‐Circuit Potential Oscillations in Alkaline Media

“…2~ As has been described in the literature, this oxidation to form Cu20 proceeds via a two-step mechanism involving the Cu~+ur~aoe species. 21 In open circuit the reactions involved are 2Cu ---> 2Cu~rf~o~ + 2e- [5] 1/2 02+H20+2e --->2OH [6] 2Cu + 1/2 02 + H20 ---> 2Cu~f,o~ + 2 OH- [7] 1. 2Cu~+u~aoe + 2 OH ~ Cu~O(s) + H20 [8] The cuprous oxide formed in alkaline medium, dissolves to form complexing species such as Cu~O2H-and Cu~O~-, according to Eq.…”

Effect of electrode surface area on chaotic attractor dimensions

“…Iron dissolution, particularly in acidic media, has been investigated by means of both experiments (Diem and Hudson, 1987;Newman, 1983, 1986a,b;Podesta et al, 1979;Li et al, 1990) and models (Franck and FitzHugh, 1961 ;Pearlstein and Johnson, 1990;Wang et al, 1990;Talbot et al, 1985). Copper electrodissolution has been studied in both phosphoric acids (Albahadily and Schell, 1988;Tsitsopoulos et al, 1987) and in acidic chloride solutions (Bassett and Hudson, 1988, 1989a,b, 1990, and nickel has also received some attention (Lev et al, 1988).…”

“…This current is a measure of the overall reaction rate on the electrode surface. In this manner, several types of interesting periodic and chaotic dynamic behavior have been found, such as period doubling to chaos (Albahadily and Schell, 1988), quasiperiodicity, Shil'nikov chaos, and period doubling of tori (Bassett and Hudson, 1989a, 1989b.…”