Coupling Between Local and Global Oscillations in Palladium-Catalysed Methane Oxidation

TL;DR

This study explores how local and global oscillations in methane oxidation catalyzed by palladium nanoparticles are interconnected, revealing how gas flow influences dynamic modes and oscillatory behavior through thermal coupling and synchronization.

Contribution

It uncovers the mechanisms linking local facet reconstructions and global oscillations in Pd-catalyzed methane oxidation, highlighting the role of gas flow and thermal coupling in dynamic behavior.

Findings

Low gas flow causes local facet reconstruction without global oscillation.

High gas flow induces chaotic transformations leading to global oscillations.

Global oscillations are linked to thermal coupling and weak synchronization.

Abstract

The interplay between order and disorder is crucial across various fields, especially in understanding oscillatory phenomena. Periodic oscillations are frequently observed in heterogeneous catalysis, yet their underlying mechanisms need deeper exploration. Here, we investigate how periodic oscillations arise during methane oxidation catalysed by palladium nanoparticles (Pd NPs), utilizing a suite of complementary operando techniques across various spatial scales. We found that reaction intensity and collective dynamic modes can be tuned by the reactant gas-flow rate. At lower gas-flow rates, we observed periodic facet reconstruction of Pd NPs correlated with repeated bubbling behaviour at the Pd/PdO interface, without evident global oscillatory responses. Conversely, at higher gas-flow rates, Pd NPs undergo chaotic transformations between metallic and oxidized states, resulting in overall oscillation. Integrating our observations at different gas-flow rates, we attributed the emergence of global oscillation to thermal coupling regulated by gas flow and connected local and global dynamics through a weak synchronization mechanism. This work demonstrates the correlations between open surfaces and interfaces, chaos and regularity, and dissipative processes and coupling behaviour. Our findings offer critical insights into the complexity behind catalytic oscillations and provide guidance for modulating oscillatory behaviours in catalytic processes, with significant implications for both science and industry.