Investigating Rhodanine film formation on roughened Cu surfaces with electrochemical impedance spectroscopy and surface-enhanced Raman scattering spectroscopy

• Time dependent film formation was monitored by Impedance and Raman Spectroscopy.
• Two loops in the Nyquist plot are found on rough surfaces and are related to film growth.
• Raman spectra intensity decreases with time, an effect attributed to film formation.

The inhibitory effect of Rhodanine (RD) on copper in acidic media has been investigated by electrochemical impedance spectroscopy (EIS) and surface-enhance Raman scattering (SERS) spectroscopy. Roughened copper was used for EIS experiments to better compare with SERS results. The EIS results show two loops in the Nyquist plot, one of which is associated with protective film growth on the rough surface after 1 h. The SERS spectra showed a marked decrease in intensity after 1 h, which is attributed to formation of thick films opaque to the laser. The film thickness after 2 h was determined to be ∼200 nm from atomic force microscopy (AFM).