Water-soluble Au nanocages for enzyme-free H2O2 sensor and 4-nitrophenol reduction†
Abstract
In this paper, water-soluble, high yield and quality, quasi-spherical Au nanocages have been successfully prepared via a galvanic replacement reaction with HAuCl4 in water at room temperature, where monodisperse, quasi-spherical Ag nanocrystals are used as sacrificial templates. Quasi-spherical Au nanocages were employed as both an enzyme-free electrochemical sensor and in catalytic application, which showed superior performance compared to solid and nanocrystals with other structures. In the enzyme-free H2O2 detection, the quasi-spherical Au nanocages based biosensor exhibited long linearity, a low detection limit, high stability and good selectivity. The enzyme-free H2O2 sensor also exhibited excellent selectivity for H2O2 in comparison to other normally co-existing electroactive species, such as ascorbic acid, uric acid and glucose. Furthermore, Au nanocages were also found to serve as a more effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 than Au nanocrystals with other structures. The reduction has an activity parameter of 4000 sā1 gā1, which is also significantly higher than other Au or Ag based nanomaterials in previous research.