Fabrication of hierarchical β-Bi2O3/AuAg microspheres for sensitive, selective and rapid detection of environment pollutants by surface-enhanced Raman spectroscopy

Abstract

In this paper, we report a novel surface-enhanced Raman spectroscopy (SERS) substrate based on hierarchical β-Bi₂O₃/Au₂Ag₂ microspheres for rapid, sensitive and selective detection of environment pollutants including o-dianisidine (o-diASD) and Hg²⁺ in environmental samples. The sheet-like β-Bi₂O₃ not only provides large specific surface areas for adsorption of molecules and AuAg, but also emerges as semiconductor matrix with chemical enhancement combined with AuAg with electromagnetic enhancement, making promising SERS activity. Particularly, the β-Bi₂O₃/Au₂Ag₂ shows high SERS performance for 4-mercaptobenzoic acid and TMB with minimum detectable concentration of 0.1 μg/L with enhancement factor of 3.1 × 10⁷ and 6.3 × 10⁷, respectively. The density functional theory simulations were further adopted to explain the high SERS activity and selectivity for o-diASD and TMB. Finally, the β-Bi₂O₃/Au₂Ag₂ was applied to direct detection of o-diASD, and indirect detection of Hg²⁺ by TMB marking in environmental samples. The linearity range of 0.5-200.0 and 0.2-500.0 μg/L with limit of detection of 0.2 and 0.07 μg/L for o-diASD and Hg²⁺ ions can be achieved, respectively. This method provides a novel strategy in designing and fabricating SERS substrates with high performance for rapid, sensitive and accurate analysis of environmental pollutants.

Keywords: AuAg; DFT simulations; Environment pollutants; Surface-enhanced Raman spectroscopy; β-Bi(2)O(3).