Electrochemically programmed evolution of 3-dimensional Ag-microstructure dictating dramatic Raman amplification for sensitive detection of molecules

Surface-enhanced Raman scattering (SERS), as a commonly utilized non-destructive analytical technique, has been widely applied in chemical and environmental fields to identify the trace amounts of analytes. However, instability and low reusability of substrate remains an unresolved challenge. In accordance with the necessity for effective SERS-substrate, we have directly deposited 3-dimensional Ag microstructures on glassy carbon surface through programmed electrodeposition varying the electrode potential in a particular sequence; and thereby morphology-controlled Agdeposits such as densely packed microflake structure and sparsely scattered micro-skein structure are eventually developed. Interestingly, morphological properties of as-prepared Ag-deposits have a big influence on Raman signal enhancement; the SERS activities are highly dependent on the presence of protruded sharp edge on metallic surface that led to enlargement of surface area. When using microflake Ag-deposit as a SERS substrate, enhancement factors of 5.2 x 107 and 3.0 x 106 are achieved for 4-ATP and thiram, respectively. The SERS performances are better and comparable to those of previously reported Ag-based substrates. In addition, Ag-deposit exhibited highly reproducible SERS signals, which implies a homogeneous distribution of active sites responsible for signal enhancement. This work thus opens a new strategic dimension preparing an efficient SERS substrate by a programmed electrochemical deposition process.

Automated summary

This study successfully deposited 3-dimensional silver microstructures on a glassy carbon surface using programmed electrodeposition. The morphology-controlled silver deposits showed enhanced Raman signals and exhibited good reproducibility.