Effect of Argon Plasma Treatment on Surface-Enhanced Raman Spectroscopy of Polypyrrole Deposited on Electrochemically Roughened Gold Substrates

Abstract

In this work, polypyrrole (PPy) films were electrodeposited on electrochemically roughened gold substrates modified by argon plasma treatment. First, a gold substrate was roughened by a triangular-wave oxidation-reduction cycle (ORC) in an aqueous solution containing 0.1 N HCl. Then the roughened gold substrate was further treated by argon plasma. Encouragingly, the surface-enhanced Raman scattering (SERS) spectroscopy of polypyrrole electrodeposited on this roughened gold substrate modified by argon plasma treatment exhibits a higher intensity by 8-fold, as compared with the SERS of PPy electrodeposited on an unmodified roughened gold substrate. Meanwhile, the electropolymerization for pyrrole monomers occurring on the modified roughened gold substrate is easier. Also, the nucleation and growth of electropolymerization of pyrrole monomers on the modified and unmodified gold substrates are different.

Improved surfaced-enhanced Raman scattering based on electrochemically roughened silver substrates modified through argon plasma treatment

“…1(a) demonstrates the typical features of a rough surface, consistent with Liu's study [42], but with a certain degree of coalescence of the Ag grains (10-100 nm in size) and hills (100-300 nm in size) with each Ag grain remaining clearly distinguishable, demonstrating the presence of microstructures <100 nm in size [7,40,43]. The two substrates (Liu's and ours) possess different surface morphologies because of the lower power of the plasma employed in this study [38,39].…”

“…While holding the potential at the cathodic vertex, the roughened Ag electrode was removed from the solution, rinsed thoroughly with deionized water, and dried in a vacuum dryer prior to subsequent treatment. Finally, the roughened Ag substrate was further treated with Ar plasma, typically by mounting it in a PD-2 plasma system (Samco, Kyoto) in which the discharge was excited by a radio frequency (RF) generator at 13.56 MHz at an Ar gas pressure of 50 mTorr and a power of 25 W for a duration of 5 min, to provide what we call herein the "modified roughened Ag substrate" [38,39].…”

“…Both of these plasmas were capable of removing the SAMs from the Au surfaces within 60 s; the hydrogen plasma pro- To the best of our knowledge, combining several roughening methods to obtain metal substrates suitable for SERS studies has not yet been investigated in great detail. In previous studies, we developed a new SERS-active Au substrate that we roughened through the use of both triangular-wave ORCs and plasma treatments under various preparation conditions [38,39]. Because the SERS technique requires the presence of structural features having dimensions of 10-100 nm on the surfaces [7,40] for plasma treatment to be an effective cleaning procedure it is necessary that it removes some roughened substrates from the surface without destroying all of the critical microstructures.…”

Improved surface-enhanced Raman scattering based on Ag–Au bimetals prepared by galvanic replacement reactions

“…Another important application based on the SP phenomena is surface-enhanced Raman scattering (SERS) [3,4]. In collecting Raman signals of organic compounds that are present in a system at very low concentration levels, SERS spectroscopy was employed to enhance the detection [5,6].…”

“…As shown in our previous studies [32,33], we prepared electrochemically roughened Au substrates modified by underpotentially deposited silver and copper to further successfully improve the SERS spectroscopies of electrodeposited polypyrrole (PPy). By combining the technologies of oxidation-reduction cycles (ORCs) and plasmas treatments in roughening metal substrates, we also developed a SERSactive Au substrate to enhance the SERS spectrum of deposited PPy [3]. In this work, electrochemically roughened Ag substrates with Ag-Au bimetals synthesized via galvanic replacement of Ag with Au were first prepared.…”