Electrochemical deposition of Rh as an active UV-SERS substrate

The transition metal Rh is highly active in surface-enhanced Raman scattering (SERS) under ultraviolet activation. The electrochemical deposition behavior of Rh³⁺ on Au electrode was studied using cyclic voltammetry (CV) and a layer of Rh was prepared on Au substrate by constant potential step method. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemical method were employed to characterize the Rh layer. The experimental results show that a uniform Rh layer has been obtained on Au surface. Electrochemical measurements demonstrate that the resulting Rh layer exhibits the same electrochemical properties as those of bulk Rh in sulfuric solution. The rough Rh substrate was prepared by using the following strategy:firstly, a rough Au substrate was prepared by electrochemical method, and then a layer of Rh was electrochemically deposited on the rough Au surface. The obtained Rh film has the roughness similar to that of Au substrate and exhibits good SERS activity when using pyridine as the probe molecule.