IN-SITU IR SPECTROSCOPIC CHARACTERIZATION OF SURFACE OXIDE SPECIES ONGLASSY-CARBON ELECTRODES

The surface oxide species produced by electrochemical pretreatment of a glassy carbon electrode were characterized using in situ Fourier tra nsform IR spectroscopy and electrochemical techniques in aqueous (H2O) and deuterated water (D2O) solutions. This study presents the first i n situ IR evidence of the surface oxide species on glassy carbon elect rodes in aqueous solution. The results showed that the potential-depen dent frequency shift is about 30 cm-1 V-1 for quinone-like species in deuterated water. There is a distinctive potential dependence for carb oxylic-like species. We also investigated the effect of potential chan ges on the surface composition (i.e. transformation between quinone an d hydroquinone etc.). On the basis of the reflectance theory of the su rface film on a moderate-adsorption substrate, the origin of the chang es in the spectral band and potential-dependent relationship are discu ssed. The open-circuit potential decay results implied that the acid-b ase behaviour is similar to that of graphite oxide.