Self-dispersed bimetallic NiRu nanoparticles on CeO₂ for CO₂ methanation

Redispersing bimetallic active nanoparticles in a heterogeneous catalyst can significantly improve metal utili-zation and catalytic performance, but it is very challenging. In this work, we report a feasible method to redisperse large bimetallic NiRu particles (30-40 nm) on the CeO2 support into small alloyed NiRu nanoparticles (3-5 nm) in an Ar gas atmosphere (NiRu/CeO2-Ar). During the high-temperature treatment, Ru metal in big bimetallic NiRu particles migrated to the surface of small alloyed nanoparticles because of the metal-phase separation, forming more Ni-Ru metal interfaces. As a result, NiRu/CeO2-Ar showed much better catalytic performance in CO2 methanation than the pristine catalyst (NiRu/CeO2) and the catalysts treated in air, H2, and reactant gases, respectively. Experimental and theoretical calculation results reveal that the newly generated Ni-Ru metal interfaces are conducive to the adsorption of CO2 and further direct dissociation into CO*, thus enhancing the catalytic performance. This work provides a reliable strategy to redisperse bimetallic NiRu nanoparticles into small ones with more intermetallic interfaces.