The adsorption of benzylamine on a polycrystalline gold electrode: A combined spectroelectrochemical study

Authors:

• Teresa Renata Łuczak,
• Maria Bełtowska-Brzezinska,
• Michael Bron,
• Rudolf Holze

Abstract

The adsorption of benzylamine on a polycrystalline gold electrode from aqueous solutions of KClO₄ and HClO₄ has been studied using differential capacitance measurements (tensammetry) and in situ surface enhanced Raman scattering (SERS). Differences in adsorption parameters of benzylamine adsorbed from neutral solutions at θ < 0.3 and θ > 0.7 can be explained on the basis of the reorientation of adsorbate molecules. Values of the free enthalpy of adsorption ΔG⁰_ad = -40.0 kJ · mol^-1 and the interaction coefficient a = - 1 at θ < 0.3 and ΔG⁰_ad = -24.3 kJ · mol^-1 with a = 0.55 at θ > 0.7 were obtained. SERS results indicate an edge-on adsorption of benzylamine from KClO₄ solution, with a small contribution from molecules adsorbed flat on the gold surface. For benzylamine adsorbed on gold from acidic solution an end-on orientation of molecules with an interaction via the amino group is concluded.