Details

Autor(en) / Beteiligte

• Hoogvliet, J.C.
• van Bennekom, W.P.

Titel

Gold thin-film electrodes: an EQCM study of the influence of chromium and titanium adhesion layers on the response

Ist Teil von

• Electrochimica acta, 2001-11, Vol.47 (4), p.599-611

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2001

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• The effect of the adhesion layer between gold films and quartz on the response of an electrochemical quartz crystal microbalance (EQCM) has been investigated in 0.1 M HClO 4 and in 0.1 M phosphate buffer pH 7.4. Cyclic voltammetry (CV) was applied in an anodic potential range, with polished and unpolished crystals, provided with a Cr or Ti adhesion layer. Crystals with Cr undercoatings showed—in HClO 4 and in buffer—oxidation currents and frequency shifts due to dissolution of Cr in a potential range in which gold oxidation also takes place. This led to loss of resonance of the crystal and/or to an increase in surface roughness. The deleterious effects of Cr are most pronounced with unpolished crystals. Crystals with Ti undercoatings neither showed a sign of oxidation or dissolution of adhesion metal, nor a significant increase in surface roughness upon repeated cycling, probably due to passivation of Ti by a thin oxide film, and its resistance to dissolution. The small positive frequency shifts observed upon repeated cycling in stirred solutions of HClO 4 and phosphate buffer, with unpolished crystals in particular, are most likely due to dissolution of gold. The oxygen chemisorption on gold in HClO 4 and in buffer, and the enhanced dissolution of gold in the presence of small concentrations (0.5 mM) of chloride in HClO 4, could be very well studied with Ti-coated crystals. For applications in the anodic potential range (extending into the region of oxygen chemisorption on gold), crystals with Cr adhesion layers should not be used.