Spatially ensemble of polydopamine-protected-Au nanocrystals on Fe3O4@SiO2@γ-AlOOH microflower for improving catalytic performance

Abstract

Advanced nanocatalysts integrating with high activity and recyclability is one of the most important issues in heterogeneous catalysis. Magnetic hierarchical nanostructures comprising noble metal nanocrystals confined within a protecting penetrable shell will be favored as an efficient candidate toward robust catalytic reactions. This work reports a proof-of-concept magnetic separable nanocatalyst with the polydopamine (PDA)-confined-Au-nanocrystals assembled on the hierarchical surface of Fe3O4@SiO2@γ-AlOOH microflower (Fe3O4@SiO2@γ-AlOOH@Au/PDA). Because of the high surface area of γ-AlOOH hierarchical nanoarchitectures, the loading capacity and dispersity of Au nanocrystals are both improved. These magnetic microflowers present excellent catalytic efficiency and cycling performance in reduction of 4-nitrophenol to 4-aminophenol, which can be ascribed to the superior structure of catalyst. After 9 cycles, the activity of Fe3O4@SiO2@γ-AlOOH@Au/PDA maintains as high as 97.3% due to the protection of PDA shell. In comparison to the spherical Fe3O4@SiO2@Au/PDA, the as-prepared Fe3O4@SiO2@γ-AlOOH@Au/PDA microflowers exhibit quicker catalytic dynamic. The concept of hierarchical nanostructure and penetrable PDA protective layer will be instructive for fabricating high-performance nanocatalysts.