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Semiintegral Analysis in Cyclic Voltammetry: Determination of Surface Excess and Concentration In the Presence of Weak Adsorption and Thin Films Michael S. F r e d and Anna Brajter-Totb* Department of Chemistry, University of Florida, Gainesville, Florida 3261 1-2046 (Received: March 6, 1992; In Final Form: July 30, 1992) Semiintegral analysis is used as an effective method for determining surface coverage (Le., initial surface excess, r*)from voltammetry in the presence of weak adsorption. Both *'I and bulk concentration (e) can be determined from the semiintegration of a single voltammogram. The approach is illustrated using p-benzoquinone (pBQ)where the adsorption and diffusion response are indistinguishable,characteristicof weak adsorption. A surface ex- of 3 nmol/cm2was determined via semiintegration and confirmed using chronocoulometry. Advantages and disadvantages of the method relative to chronocoulometry are discussed. The semiintegralanalysis approach is extended to cases where the elwtrcdc surface is covered by a thin film where the thickness is sufficiently small so that mass transfer within the Nm is not significant (Le., thickness
