A SPECTROELECTROCHEMICAL STUDY OF CHEMISORPTION, ANODIC POLYMERIZATION AND DEGRADATION OF SALICYLIC-ACID ON CONDUCTOR AND TIO2 SURFACES

In situ uv-vis and SNIFTIR spectroscopy and their combination with electrochemical techniques have been used for investigation of interaction of salicylic acid (SA) with various forms of TiO2 (pyrolyzed layers of TiO2 and a collodial solution of TiO2 Q-particles). For comparison, conductor electrodes (Pt, Au, Glassy carbon and F-doped SnO2) have been used. SA (0.01-0.1M aqueous or acetonitrile solutions) is chemisorbed on TiO2 surfaces through its carboxylic group forming C-T complexes with TiO2. Electrochemical oxidation of SA on conductor electrodes leads to a formation of an insulating layer due to anodic polymerization. A similar polymerization process has been observed on illuminated TiO2. Besides that, SA undergoes a photoanodic degradation on TiO2 where formic acid as one of intermediates has been identified.