Ag-modified CuO cavity arrays as a SERS-electrochemical dual signal platform for thiram detection.

Rapid and sensitive determination of pesticide residues in fruits and vegetables is critical for human health and ecosystems. This paper used an Ag-modified CuO sphere-cavity array (CuO@Ag) electrode as a thiram SERS/electrochemical dual readout detection platform. Numerous Raman "hotspots" generated by uniformly distributed silver nanoparticles, charge transfer at the CuO@Ag interface, and the formation of Ag-thiram complexes contribute to the significant enhancement of this SERS substrate, which results in excellent SERS performance with an enhancement factor up to 1.42 × 106. When using SERS as the readout technique, the linear range of the substrate for thiram detection was 0.05-20 nM with a detection limit (LOD) of up to 0.0067 nM. Meanwhile, a correlation between the value of change in current density and thiram concentration was established due to the formation of stable complexes of thiram with Cu2+ generated at specific potentials. The linear range of electrochemical detection was 0.05-20.0 µM, and the detection limit was 0.0167 µM. The newly devised dual-readout sensor offers notable sensitivity and stability. The two signal readout methods complement each other in terms of linear range and detection limit, making it a convenient tool for assessing thiram residue levels in agro-food. At the same time, the combination of commercially available portable equipment makes on-site monitoring possible.

Synthesis and Growth Mechanism of SiS2 Rods.

The SiS2 rods exhibit a significant anisotropy property applied in a special field such as in the one of all-solid-state lithium-ion batteries and so on. In this work, the orthorhombic SiS2 rods with high chemical/phase purity were prepared by an elemental method, either through a boiling or a steaming process, at 1023-1073 K for 3 h and under the saturated S-vapor pressure (2.57-3.83 MPa) in a closed sealed-tube system. The composition, crystal structure, morphology, and growth mechanism were investigated. Results showed that the growth orientation of SiS2 along the <0 0 1> is intrinsically governed by the crystal structure motif. It could exist in both processes and the latter tends to show in macroscopic morphology. Using the pressure-temperature diagram, structure refinement, pole figures, image analyses, and so forth, factors influencing the purity and growth of SiS2 rods were concluded from the thermodynamics and kinetics viewpoints.