Linking electrocatalytic turnover to elementary step rates in hydrocarbon fuel oxidation

TL;DR

The paper shows how to improve propane fuel oxidation on platinum by understanding and resolving conflicts between different reaction steps.

Contribution

The study introduces a step-resolved method to link electrocatalytic turnover rates to individual reaction steps in propane oxidation.

Findings

Low propane oxidation activity on Pt is due to mismatched optimal potentials for adsorption, conversion, and CO oxidation.

Applying alternating potentials improves overall reaction rates by optimizing individual steps separately.

The step-resolved approach provides a framework for designing better electrocatalysts for complex reactions.

Abstract

Maximizing steady-state turnover rates is a central goal in electrocatalysis research, but improving one reaction step often impedes others. Navigating these trade-offs requires methods that systematically reveal how a single parameter change affects all key steps of a reaction mechanism. Here, we use electrochemical mass spectrometry to determine the potential-dependent rates of each principal step in propane oxidation on Pt and directly relate them to the steady-state turnover rate. Our analysis reveals that low steady-state activity arises from a mismatch between the optimal potentials for adsorption, conversion, and *CO oxidation. By applying alternating potentials to individually optimize adsorption and oxidation, we overcome this limitation and achieve rates exceeding those under constant-potential operation. This step-resolved approach clarifies how individual processes interact to govern overall activity and provides a framework for the rational design of electrocatalysts carrying out complex reactions at steady-state.

The electrocatalytic oxidation of propane fuel is slow on Pt. By analyzing the rate of its individual steps, the authors show that slow propane oxidation is caused by a mismatch between the electrode potentials that promote propane adsorption, conversion of intermediates, and oxidation to CO2.

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