Long‐Lasting Oscillations in the Electro‐Oxidation of Formic Acid on PtSn Intermetallic Surfaces

Abstract

Even when in contact with virtually infinite reservoirs, natural and manmade oscillators typically drift in phase space on a time-scale considerably slower than that of the intrinsic oscillator. A ubiquitous example is the inexorable aging process experienced by all living systems. Typical electrocatalytic reactions under oscillatory conditions oscillate for only a few dozen stable cycles due to slow surface poisoning that ultimately results in destruction of the limit cycle. We report the observation of unprecedented long-lasting temporal oscillations in the electro-oxidation of formic acid on an ordered intermetallic PtSn phase. The introduction of Sn substantially increases the catalytic activity and retards the irreversible surface oxidation, which results in the stabilization of more than 2200 oscillatory cycles in about 40 h; a 30-40-fold stabilization with respect to the behavior of pure Pt surfaces. The dynamics were modeled and numerical simulations point to the surface processes underlying the high stability.

Voltage Inversion Caused by Self-organized Oscillations in a Direct Formic Acid Fuel Cell

“…These species react with CO ad via the Langmuir-Hinshelwood mechanism, releasing free sites which causes the anodic overpotential to decrease and the new cycle begins again [1] [9]. The emergence of oscillatory kinetics during the electro-oxidation of formic acid has been extensively studied with the aid of techniques such as infrared spectroscopy [12] and numerical modeling [13] [14]. Mota et al [15] have showed kinetic instabilities in a DFAFC using H 2 on the cathode instead of O 2 .…”

Coupled slow and fast surface dynamics in an electrocatalytic oscillator: Model and simulations

“…We believe this process to be responsible for the slow evolution. 8,9,11,12 Based on this reasoning, we have been able to design and test the concept of long-lasting electrochemical oscillators, 17,18 and an increase of about 30-40 times the number of oscillatory cycles was observed.…”

Ordered Intermetallic Nanostructured PtSb/C for Production of Energy and Chemicals

“…In addition, the synthesis of these phases as nanoparticles enables their application in real systems. Few studies have used ordered intermetallic phases as active material in electrochemical reactions, even though this type of nanoparticles presents promising performance [15][16][17][18][19][20][21]. In particular, ordered intermetallic PtSb constitutes a potential electrocatalyst for alcohol electrooxidation [17].…”