Ellipsometric, Electrochemical, and Elemental Characterization of the Surface Phase Produced on Glassy Carbon Electrodes by Electrochemical Activation

Ellipsometry was used to monitor the In situ growth of a fllm on a glassy carbon electrode, whlch was electrochemlcally anodized at 1.8 V In 0.1 M H,SO,. The layer grew contlnuously In an uninhlblted fashion wlth constant optical constants to a thlckness of at least 925 nm. I t was nearly transparent at wavelengths of 545 and 632.8 nm. X-ray and elemental analysls of bulk quantltles of the phase Indicate that It Is an amorphous form of graphlte oxlde. Comblned elllpsometrlc and electrochemical measurements show that the phase activates the surface and that deactivation occurs upon extennslve reductlon of the layer. The electrode actlvlty, as monitored by the voltammetrlc response In dilute solutlons of catechol, hydroquhne, and 2,3-dlcyanohydroqulnone, varled wlth the extent of reductlon of the layer.