Does more carbon deposition necessarily lead to worse catalytic performance?

Conventional wisdom holds that higher carbon accumulation during reaction invariably deteriorates catalytic activity, yet emerging high-performance catalysts have demonstrated remarkable activity despite severe coke encapsulation, suggesting a complex interplay between carbon accumulation and catalytic behavior. Herein, we employ the coke-generating dry reforming of methane as a model system, utilizing the widely-used Ni/Ce_xZr_1-xO₂ (0 ≤ x ≤ 1) catalysts to investigate whether more carbon deposition necessarily leads to worse catalytic activity. The results demonstrated that the most active 0.6Ni/CeO₂ generated the most coke, with extensive formation of graphitic carbon that ultimately covered the entire catalyst. In contrast, the least active 0.6Ni/ZrO₂ exhibited minimal coke accumulation, due to an initial-stage complete coke coverage that passivated further carbon deposition. Our work reveals that catalytic activity can be partially preserved even with substantial coke, provided the deposited carbon dynamically migrates away from the active sites, thereby enabling the periodic re-exposure of catalytically active regions.