ZnGa₂O₄ Nanorod Arrays Decorated with Ag Nanoparticles as Surface‐Enhanced Raman‐Scattering Substrates for Melamine Detection

Abstract

The availability of sensitive, reproducible, and stable substrates is critically important for surface‐enhanced Raman spectroscopy (SERS)‐based applications, but it presently remains a challenge. In this work, well‐aligned zinc gallate (ZnGa2O4) nanorod arrays grown on a Si substrate by chemical vapor deposition were used as templates to fabricate SERS substrates by deposition of Ag nanoparticles onto the ZnGa2O4 nanorod surfaces. The coverage of the Ag nanoparticles on the ZnGa2O4 nanorod surfaces was easily controlled by varying the amount of AgNO3. SERS measurements showed that the number density of Ag nanoparticles on the ZnGa2O4 nanorod surfaces had a great effect on SERS activity. The SERS signals collected by point‐to‐point and SERS mapping images showed that as‐prepared SERS substrates exhibited good spatial uniformity and reproducibility. Detection of melamine molecules at low concentrations (1.0×10−7 M) was used as an example to show the possible application of such a substrate. In addition, the effect of benzoic acid on the detection of melamine was also investigated. It was found that the SERS signal intensity of melamine decreased greatly as the concentration of benzoic acid was increased.

Synthesis of Hollow BiVO4/Ag Composite Microspheres and Their Photocatalytic and Surface‐Enhanced Raman Scattering Properties

“…[50,51] The strong and mediumstrong Ramanb ands at 1648, 1575, 1510, 1361, 1310, 1187, 774, and 611cm À 1 are assigned to the xanthene ring stretch, ethylamine group wag, and carbon-oxygen stretch of R6G. [52] The SERS response of the BiVO 4 /Ag composite microspheres was studied with increasing nominal surfacec overage of R6G molecules. Figure 5B shows the typical SERS spectra of R6G with variousc oncentrations ranging from 1.0 10 À8 to 1.0 10 À13 m.T he Ramanp eaks remained clearly observable even as the concentration of R6G solution was decreased to 1.0 10 À12 m.T he SERS enhancement factors (EFs) for R6G adsorbed on the BiVO 4 /Ag composite microspheres were calculated according to the equation [53] EF = (I SERS /I bulk )(N bulk /N surface ), in which I SERS and I bulk denote the integrated intensities for the 1510 cm À1 band of the 1.0 nm R6G adsorbed on the BiVO 4 /Ag composite microspheres and 1.0 mm R6G on glass, respectively,a nd N SERS and N bulk represent the corresponding numberso f R6G molecules excited by the laser beam.…”

Review on Nanomaterial-Based Melamine Detection

“…Notably, in the main stream these reports displayed complications in their optimization along with the great recoveries and linearity in melamine detection, as summarized in Table 3. The majority of nanowires/nanorods/nanotubes-based composite arrays engaged in melamine detection were attributed to the SERS effect of the substrate fabricated and subjected to the analysis [197][198][199][202][203][204][205][206][207][208]210,211,[213][214][215][216][217]. In contrast, some tactics, such as fluorescence [196], electrochemical [200,201], electrochemiluminescence (ECL) [209], and voltammetry [212] were also employed in the discriminative assay of melamine.…”

Urchin-like m -LaVO 4 and m -LaVO 4 /Ag microspheres: Synthesis and characterization

“…Recently, the assembly of noble metal nanoparticles on semiconductor structures such as nanospheres, [7,8] rods, [9,10] tubes, [11,12] wires, [13,14] fibers, [15,16] and sheets [17] has raised great interest. These hybrid nanostructures can combine the unique mechanical and electronic properties of the semiconductor structures with the size-and shape-dependent optical properties of noble metal nanoparticles.…”