Stabilizing Active Metal Nanoclusters within Mesopores via an Inner Surface-Confinement Strategy

Mesoporous support-encapsulated fine-size metal nanoclusters hold great potential for catalytic applications by virtue of their high reactivity and fast mass transport kinetics but suffer greatly from particle aggregation and/or sintering, especially under high reaction temperatures. Here, we report an inner surface-confinement strategy to stabilize a variety of ultrafine metal nanoclusters (M = Pt, Pd, Ni, and Ag) inside mesoporous silica supports. The strategy is based on the selective N functionalization of the inner surface of mesopores, which not only assures the direct growth of ultrafine metal nanoclusters therein but also endows the active metal nanoclusters with excellent thermal stability via N-metal coordination. Remarkably, the mesopore-encapsulated N-coordinated Pt nanoclusters are particularly selective for making α,β-unsaturated alcohol, benefiting from their energetically favored reaction pathway for end-on binding α,β-unsaturated aldehyde reactants and heterolytic dissociation of hydrogen. The synthetic methodology is expected to provide new guidelines to improve the thermal stability of mesopore-encapsulated metal nanoclusters for superb catalysis.