Oxygen Pumping Effect of Interfacial MoO _x Mitigates Coking in NiCo/CeO ₂ –Al ₂ O ₃ Catalysts for Dry Reforming of Methane

Non-noble Ni-based catalysts are highly active for dry reforming of methane (DRM) but suffer from severe carbon deposition. To address this challenge, we synthesized Mo-modified bimetallic NiCo/CeO 2 –Al 2 O 3 catalysts via sol–gel method. We have demonstrated that an optimal Mo/Ni atomic ratio of 0.15 balances the trade-off between activity and coking resistance, achieving a stable 65% CH 4 conversion at 700 °C over 100 h of DRM while maintaining superior coke resistance. Based on comprehensive experimental analyses, we propose that during DRM, surface and interfacial MoO x species act as the oxygen pump (MOP), generating reactive oxygen (O*) from CO 2 dissociation and channeling it to adjacent components. By creating an oxygen-rich local chemical environment, this mechanism concurrently passivates the metal surface and progressively shifts the CH 4 activation pathway from deep decomposition to oxidative dehydrogenation, enabling efficient carbon elimination at the cost of reduced activity. This work elucidates the oxygen pumping effect of interfacial MoO x, providing a practicable strategy for designing coking-resistant catalysts for DRM and other high-temperature processes.