Silica-coated silver/gold composite nanoboxes having enhanced catalytic performances and reusability

• SiO2-coated Ag/Au nanoboxes were synthesized via galvanic replacement.
• The nanoboxes catalyze the degradation of 4-nitrophenol efficiently.
• The catalytic reaction occurs on the inner and the outer surfaces of the nanoboxes.
• Catalytic performances were sustained after being recycled repeatedly.

SiO2-coated Ag/Au composite hollow nanoboxes, Ag0.7Au0.3@SiO2 core–shell nanocomposites, having high catalytic performances and enhanced catalytic reusability have been fabricated via a galvanic replacement reaction of SiO2-coated silver nanocubes. Compared with SiO2-coated Ag nanocubes, SiO2-coated Ag/Au composite nanoboxes have been found to catalyze the degradation of 4-nitrophenol more rapidly in the presence of NaBH4 due to fast diffusion. In contrast to bare Ag/Au composite nanoboxes, SiO2-coated Ag/Au composite nanoboxes can be recycled continuously for the catalytic degradation of 4-nitrophenol in the presence of NaBH4. We consider that silica coating enhances the stability of Ag/Au composite nanoboxes enormously by blocking the dissolution and aggregation of nanoparticles thoroughly.

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