Thiourea adsorption on a Pt surface as detected by electrochemical methods and surface-enhanced Raman spectroscopy

The adsorption behavior of thiourea (TU) on a roughened Pt electrode was investigated by combining electrochemical methods and surface-enhanced Raman spectroscopy. It was found that TU could be dissociated on a roughened Pt surface at the open circuit potential to form a surface sulfide. The dissociation process can be effectively suppressed if the electrode is immersed into the solution with its potential controlled at a negative value. Using these tactics, we are able to perform a surface-enhanced Raman spectroscopy (SERS) study of the adsorption behavior of TU on Pt. The SERS results reveal that TU is adsorbed through its sulfur atom in a tilted way and the orientation changes with the applied potential. The study points out the importance of controlling the electrode potential properly upon immersion of the electrode into the solution.