Nonthermal Catalytic Origin in DC-Enhanced Dry Reforming of Methane Unveiled by Multimodal Operando Analyses

Catalytic dry reforming of methane (DRM) is a key reaction for the sustainable utilization of major greenhouse gases, CO₂ and CH₄. However, conventional DRM often suffers from severe catalyst deactivation due to high temperature requirements. Applying direct current (DC) to catalysts has emerged as a promising strategy to overcome these limitations, yet the underlying DC-enhanced catalytic mechanisms remain elusive. Here, we unveil the nonthermal catalytic origin of DC-applied DRM over Pd/CeO₂ through multimodal operando analyses. Spatially resolved operando infrared measurements revealed that key reaction intermediates specific to nonthermal DRM exclusively emerge on current-carrying regions of the catalyst surface under DC bias. Furthermore, operando infrared and visible absorption spectroscopy detected the trapped electrons and holes generated in CeO₂ during DC application and revealed a clear correlation between the density of injected charges and the DRM activity. Soft X-ray spectroscopic analysis uncovers an unconventional pathway of hole generation in nominally n-type CeO₂ under DC bias. These observations demonstrate that DC application induces distinct molecular and electronic species that promote CO₂ reduction and CH₄ oxidation in DRM via nonthermal pathways.