Challenges in Unravelling the Intrinsic Kinetics of Gas Reactions at Rotating Disk Electrodes by Koutecky–Levich Equation

Abstract

Rotating disk electrode (RDE) system is a widely applied technique for investigating the kinetics of these reactions limited by poor mass transfer, e.g., for reactions involving gaseous reactants of low concentration as a result of limited solubility. For irreversible reactions of apparent first-order kinetics, kinetic parameters such as the kinetic current and the rate constant are usually derived based on the Koutecky−Levich equation. In this Perspective, we will discuss several frequently encountered and important issues that may significantly reduce the accuracy of the kinetic analysis. We will focus on (i) variation or improper identification of the diffusion limiting current; (ii) deviation of the RDE system from the steady-state conditions; (iii) effect of catalyst loading; (iv) reactions with reactants of reaction order deviating from one; and (v) the mass transport limiting of more than one reactant. Possible origins of the error that affects the accuracy of the kinetic analysis will be discussed, and practical protocols to avoid such errors will be recommended.

Boosting Oxygen Reduction at Pt(111)|Proton Exchange Ionomer Interfaces through Tuning the Microenvironment Water Activity

“…To unveil how the intrinsic ORR activity changes with the introduction of proton exchange ionomer membrane as well as with the drying temperature, the kinetic current for ORR is estimated using the j – E curves and the Koutecky–Levich equation (Figure a). , From Figure a, a significant poisoning effect on the ORR by the sulfonate adsorbate can be observed. This effect is similar to that for the ORR at Pt(111) in 0.1 M HClO 4 + x M H 2 SO 4 (Figure S1c).…”

Molecular Catalysis Enables Fast Polyiodide Conversion for Exceptionally Long-Life Zinc–Iodine Batteries

“…Subsequently, the relationship between the rotation speed and current is derived from Figure f (Figure g). Calculating with the Koutecký–Levich equation, , the electron-transfer number for I 0 in Zn–I 2 batteries with Hemin catalyst is 0.758, which further demonstrates the conversion mechanism between I – and I 5 – .…”

Electrocatalysis of Oxygen Reduction on Te-Modified Platinum Stepped Crystal Surfaces

“…For that, it is necessary to understand the ORR mechanism and factors that affect ORR kinetics on the electrocatalysts . However, the complex catalyst structure in practical electrode materials limits the in-depth study of ORR kinetics. − Single-crystal electrodes with well-defined surfaces and a controlled atomic arrangement − are of great help in elucidating the reaction mechanism and unraveling the structure–activity relationship. Systematic studies of the platinum stepped surfaces with different terrace widths have provided rich information, such as the chemical properties of the electrode/electrolyte interface at the atomic level and how these properties affect its behavior. − The information gained from such studies has shed important insights into real electrocatalysts in PEMFCs. − …”