Subnano-FeO_x Clusters Anchored in an Ultrathin Amorphous Al₂O₃ Nanosheet for Styrene Epoxidation

The development of low-cost, high-performance catalysts at the atomic level has drawn scientists’ attention due to the high atom efficiency, unique structure, and potentially high catalytic selectivity. Among the atomically tailored catalysts, nanoclusters are of particular interest because they represent an underexplored medium state between isolated single atoms and typical nanoparticles. In this study, we report a wet-chemistry approach to synthesize highly dispersed subnano-FeO_x clusters anchored on an ultrathin amorphous Al₂O₃ nanosheet (or Al₂O₃-FeO_x nanosheet) and its excellent catalytic performance for selective conversion of styrene to styrene oxide. The reasons for the high catalytic performance of the Al₂O₃-FeO_x nanosheet are 2-fold. One is that the unsaturated and amorphous nature of the Fe atoms in the subnano-FeO_x clusters promotes the adsorption of styrene onto the catalytic sites of FeO_x clusters for epoxidation. The other is that the amorphous Al₂O₃ nanosheet prevents the aggregation of catalytic FeO_x clusters during the epoxidation reaction because its defective structure immobilizes the FeO_x clusters.