The investigation into catalysis of the surface or interface sites on the catalysts has long been the number one important task in catalytic science. However, the contribution of non-surface or non-interface sites in a catalyst to its catalytic performance remains unclear. This becomes even more challenging to unveil the mystery of the influence of internal vacancies/cages in a catalyst on the overall performance because of the difficulty of correlating the conventional characterization information with inner structure of a catalyst.
Yan Zhu’s group explore the first example of the contribution of internal vacancy in the Au24 cluster to the hydrogenation reaction of CO2. Au24 cluster with internal vacancy can mitigate sintering and exhibit high catalytic activity under relatively harsh reaction conditions, in contrast to the structurally similar Au25 cluster without internal vacancy. The internal vacancy in Au24 provides the cluster with much more structural flexibility, which may be crucial to resisting the aggregation of the cluster and further postponing the deactivation. Especially, the novel formation mechnism of dimethyl ether on the 24-atom gold catalyst can give chemical insight that is totally different from the conventional two-step mechanism comprising methanol synthesis via hydrogenation of CO2 and methanol dehydration to form dimethyl ether.The work tells the truth that the role of non-surface or non-interface sites in the catalysts must never be ignored in the catalytic reactions and further apparently impacts one’s understanding of the contributions of active sites on surface plus non-surface of a catalyst to the overall performance.
The work entitled “Structural Relaxation Enabled by Internal Vacancy Available in a 24-atom Gold Cluster Reinforces Catalytic Reactivity” has been published in Journal of the American Chemical Society (DOI:10.1021/jacs.9b07761).
