Mitigating Surface Deactivation for N2O Abatement Using Plasma Activated Co-reactants

Abstract

Catalyst deactivation by surface bound intermediates is a persistent challenge in plasma catalysis, often limiting conversion, product selectivity, and energy efficiency in chemical processes. In this study, we identify surface oxygen accumulation (O*) as the dominant deactivation mechanism in plasma assisted nitrous oxide (N₂O) decomposition and present a direct strategy to mitigate it. Using polycrystalline Cu/Al₂O₃ and Al₂O₃ catalysts under nonthermal plasma conditions, we show that Cu deactivates rapidly due to O* poisoning, as confirmed by time-resolved experiments and X-ray photoelectron spectroscopy (XPS). To counteract this, we introduce hydrogen based co-reactants (H₂ and CH₄) that remove surface O* by forming H₂O and CO₂, thereby regenerating active sites and restoring catalytic activity. This co-reactant approach enables efficient N₂O decomposition at ambient temperature and pressure, conditions where traditional thermal catalysis typically requires elevated temperatures (≥300 °C) and expensive noble metals. Co-reactant addition not only enhances conversion and halves energy cost, but also, when using CH₄, produces value added C₂ hydrocarbons. Density functional theory calculations support these findings, revealing that co-reactants open up more favorable reaction pathways for O* removal. These results highlight how plasma catalysis creates a multidimensional design space where plasma conditions, catalyst surface chemistry, and gas phase composition can be co-optimized. This flexibility enables the use of weakly binding, earth abundant catalysts like Cu, which are otherwise inactive under mild thermal conditions. These findings demonstrate how plasma assistance can augment heterogeneous catalysis, offering alternative avenues for efficient, low temperature transformations in both environmental remediation and synthetic applications.