Facile deposition of gold nanoparticles on core–shell Fe3O4@polydopamine as recyclable nanocatalyst

• Core–shell Fe3O4@PDA nanoparticles with tunable-shell thickness was developed.
• The application of Fe3O4@PDA as recyclable nanocatalyst support was presented.
• Deposition of Au NPs atop Fe3O4@PDA NPs with a high density was achieved.
• The nanocatalysts exhibited high catalytic performance with good stability.

A simple and green method for the controllable synthesis of core–shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs) with tunable shell thickness and their application as a recyclable nanocatalyst support is presented. Magnetite Fe3O4 NPs formed in a one-pot process by the hydrothermal approach with a diameter of ∼240 nm were coated with a polydopamine shell layer with a tunable thickness of 15–45 nm. The facile deposition of Au NPs atop Fe3O4@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The satellite nanocatalysts exhibited high catalytic performance for the reduction of p-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 8 times without detectible loss in activity. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core–shell NPs as a versatile platform for potential applications.

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