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Here, we report a novel AuAg nanoalloy embedded sheet-like β-Bi 2 O 3 (β-Bi 2 O 3 /Au 2 Ag 2) hierarchical microsphere for rapid, sensitive and selective detection of environment pollutants including o -dianisidine (o -diASD) and Hg2+ ions in environmental samples. [Display omitted] • The sheet-like β-Bi 2 O 3 /Au 2 Ag 2 was synthesized by in-situ reduction method. • High SERS activity originates from synergistic effect of AuAg and β-Bi 2 O 3. • Good selectivity, stability and repeatability for SERS analysis. • The practical applications were achieved for analysis of environment pollutants. In this paper, we report a novel surface-enhanced Raman spectroscopy (SERS) substrate based on hierarchical β-Bi 2 O 3 /Au 2 Ag 2 microspheres for rapid, sensitive and selective detection of environment pollutants including o -dianisidine (o -diASD) and Hg2+ in environmental samples. The sheet-like β-Bi 2 O 3 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-Bi 2 O 3 /Au 2 Ag 2 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-Bi 2 O 3 /Au 2 Ag 2 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. [ABSTRACT FROM AUTHOR]

Here, we report a hexagonal boron nitride/AuAg nanoalloys hybrids membrane (h-BN/AuAg) as solid surface-enhanced Raman spectroscopy (SERS) substrate for sensitive SERS detection. The AuAg nanoalloys were in-situ grown on h-BN by chemical reduction method. Then the h-BN/AuAg membrane was fabricated by simple filtration of h-BN/AuAg nanoalloys hybrids (h-BN/AuAg NAHs). The possible enhancement mechanism including electromagnetic mechanisms (EM) and chemical mechanisms (CM) were illustrated by finite-difference time-domain (FDTD) and density functional theory (DFT) simulation in detail. The proposed SERS method demonstrated high sensitivity, satisfied selectivity, good repeatability and reproducibility for the SERS detection of melamine in liquid milk samples. [Display omitted] • 1. The membrane-based SERS substrate was prepared by simple filtration procedure. • 2. The optimized SERS activity can be obtained by tuning with Au/Ag ratio. • 3. The h-BN/Au 1 Ag 3 provide analytical enhancement factor at 3.6 × 108 level. • 4. Good relationship between SERS intensity and melamine concentrations was obtained. In this work, a hexagonal boron nitride (h-BN)/AuAg nanoalloy hybrids (NAHs) was synthesized to fabricate h-BN/Au 1 Ag 3 membrane as a solid surface-enhanced Raman spectroscopy (SERS) substrate for sensitive SERS detection of melamine. The AuAg nanoalloys were in situ grown on h-BN by chemical reduction method, and the Au/Ag molar ratio was tuned to achieve optimal SERS performance. After the SERS performance of h-BN/AuAg NAHs with different Au/Ag ratios was analyzed, h-BN/Au 1 Ag 3 NAHs were chosen for SERS analysis. The h-BN/Au 1 Ag 3 membrane can be obtained through simple filtration of h-BN/Au 1 Ag 3 NAHs on chromatographic paper. As expected, the solid SERS substrates of h-BN/Au 1 Ag 3 membrane were uniform and demonstrated good selectivity, repeatability and reproducibility for SERS detection of melamine. The results demonstrate that h-BN/Au 1 Ag 3 membrane exhibited high SERS activity for 4-mercaptobenzoic acid (4-MBA) with limit of detection (LOD) at 1.0 ng L−1, and its analytical enhancement factor (AEF) reached 3.6 × 108. The possible enhancement mechanism, including electromagnetic mechanisms (EM) and chemical mechanisms (CM) were illustrated by finite-difference time-domain (FDTD) and density functional theory (DFT) simulations in detail, respectively. The concentration of melamine in the 0.05–5.0 mg L−1 range showed good linear relationship (R2 = 0.9940) with SERS intensity with LOD of 0.01 mg L−1. Finally, the recoveries of melamine in liquid milk samples are 87.7–105.7% with relative standard deviations (RSDs) in range of 0.6–2.6%, providing precise safety evaluation of melamine in milk samples. [ABSTRACT FROM AUTHOR]