Nanoparticles-in-concavities as efficient nanocatalysts for carbon dioxide reforming of methane to hydrogen and syngas

Abstract

The synergy between ceria and loaded metal nanocrystals (NCs) greatly promotes the catalytic properties for many reactions. Nevertheless, the clear relevance of structures to properties in catalytic systems is hard to establish in that the catalysts studied either featured unstable microstructures or were too heterogeneous. Herein, we show both the facile tool of NC assembly to derive stable and efficient catalytic materials, in which the metal NCs are tailored in terms of their spatial positioning on the nanometer scale (i.e., entrapped in the internal concave ceria surface or deposited on the external convex ceria surface), and how to probe their structure–function relationship. The performance for producing renewable energy sources from hazardous greenhouse gases on a NCs-in-concavities structure is distinct from that on a NCs-on-convexities configuration, elucidating a pivotal impact by the spatial positioning. The current investigation suggests that there exists a clear relationship between the surface adsorbate bonding strength/type and the catalytic properties in reforming CO₂/CH₄ to hydrogen energy and syngas. Control over the bonding strength/type and activation mechanism of the adsorbates on the catalyst surfaces through changing the support surface curvature orientation is indicated to be a potential strategy for modulating the reaction activity. The insights focus on grasping the surface chemistry of the ceria surface curvature in optimizing the catalysts and can be enlightening for rationally exploring other state-of-the-art heterogeneous nanomaterials.