Green Propylene Electrooxidation: Bridging Catalyst Design, Multi-Energy Coupling, and Reactor Engineering.

The selective electrooxidation of propylene to high-value oxygenates, such as propylene oxide (PO) and propylene glycol (PG), represents a sustainable alternative to conventional processes that suffer from severe corrosion, byproduct dependency, and safety risks. Despite recent progress in catalyst development and reaction engineering, the field continues to face critical challenges, including poor control over product selectivity, insufficient mass transfer efficiency, and a limited mechanistic understanding of reactive oxygen species generation and coupling with propylene activation. To address these issues, this review provides a systematic integration of recent advances, organizing the field along a progression from direct surface-mediated electrocatalysis, through halogen-mediated indirect oxidation in the electrolyte bulk, to multi-field-coupled tandem systems, with a focus on comparatively analyzing the catalytic performance and reaction mechanisms of different systems. Ultimately, we offer strategic perspectives for overcoming current bottlenecks. This review aims to provide both fundamental insights and practical guidelines for designing efficient, selective, and scalable electrocatalytic systems for green propylene oxidation.