Novel synthesis of Fe2O3–Pt ellipsoids coated by double-shelled La2O3 as a catalyst for the reduction of 4-nitrophenol

A facile strategy is reported for the fabrication of Pt-loaded core–shell nanocomposite ellipsoids (Fe 2 O 3 -Pt@DSL) consisting of ellipsoidal Fe 2 O 3 cores, double-layered La 2 O 3 shells and deposited Pt nanoparticles (NPs). The formation of the doubled-shelled structure uses Fe 2 O 3 -Pt@mSiO 2 as template sacrificial agent and it involves the re-deposition of silica and self-assembly of metal oxide units. The preparation methods of double-shelled metal oxides avoid repeated coating and etching and could be utilized to fabricate other shaped double-shelled composites. Characterization results indicated that the Fe 2 O 3 -Pt@DSL nanocomposites possessed mesoporous structure and tunable shell thickness. Moreover, due to the formation of Fe 2 O 3 and La 2 O 3 composites, Pt NPs can also be stabilized via deposition on chemically active oxides with a synergistic effect. Therefore, as a catalyst for the reduction of 4-nitrophenol, Fe 2 O 3 -Pt@DSL showed superior catalytic activity and reusability due to structural superiority and enhanced composite synergy. Finally, well-dispersed Pt NPs were encapsulated into the void between the shell layers to construct the Fe 2 O 3 -Pt@DSL-Pt catalyst.