Electrochemical fabrication of pyramid-shape silver microstructure as effective and reusable SERS substrate

Abstract

The high sensitivity and reproducibility are significant for the routine Surface-enhanced Raman Scattering (SERS) detection. Here, the pyramid-shape silver microstructures has been successfully synthesized using a facile electrochemical deposition method and the reaction with a two-indium tin oxides (ITO) electrode system is carried out by potentiostatic method, where only silver nitrate (AgNO3) and poly (methyl methacrylate) (PMMA) nanospheres are introduced to control the reaction process. Meanwhile, PMMA nanospheres as morphology controlled reagents are used to lead Ag units to grow in the form of pyramid-shape. The prepared pyramid-shape silver microstructures possesses high SERS activity with an average enhancement factor (EF) of 9.1 × 105, which is superior or close to some individual Ag or Au microstructures and Ag composite materials. In addition, an excellent reproducibility is achieved resulting from a relative standard deviation of 7.9%, 8.5%, 7.3%, and 8.7% measured by four Raman shifts of R6G at 612, 772, 1363, and 1650 cm−1, respectively, which is much lower than those of the commonly used SERS substrates. Importantly, the as-prepared pyramid-shape silver microstructures have been evolved as a sensitive SERS substrate for the detection of trace amounts of rhodamine 6G (R6G) and 3-mercaptopropionic acid (3MPA) down to nanomolar and millimolar concentration with excellent recyclability. Therefore, this work offers a simple way to prepare pyramid-shape silver microstructures as an effective SERS substrate and make the SERS more practicable.