Hypersensitive SERS sensor of various types of herbicide enabled by tri elements surface alloying nanoparticles

Abstract

Herein, a specific type of tri_elements SERS chemical sensor was created by the ion reduction process of the as-prepared porous silicon (PSi) substrate in a mixed solution of volumetric ratio (1:1:1) of metal solutions of gold, silver, and palladium of concentrations of 1 mM. The synthesized tri_elements SERS chemical sensor effectively detected two types of herbicide, atrazine and diuron, at ultra-low concentrations, less than the maximum amount permitted globally. The as-prepared porous Si was created via laser-stimulate etching (LSE) process by (60 mW/cm²) laser power density, (5 mA/cm²) current density, and (12 min) etching time. The created tri_elements SERS chemical sensor was inspected at various herbicide concentrations from 5 × 10^–5 to 5 × 10^–8 M. The results of the fabricated tri_elements sensor with a cauliflower-shaped surface alloy configuration showed an excellent Raman enhancement factor of about 4.2 × 10⁶ and 4 × 10⁶ with the lowest detection limit of about 3 × 10^–11 M and (2 × 10^–11 M) and an excellent reproducibility of minimum variation of about 2.9% and 3.1% for diuron and atrazine respectively. The density of hot spot sites and the aggregated tri-metallic nanoparticles’ size and shape are the leading causes of the sensors’ hypersensitivity.