Reversibility-Dependent Photovoltammetric Behavior of Electroactive Compounds on a CdS-Graphene Hybrid Film Electrode.

Photovoltammetric behaviors of irreversible, quasi-reversible and reversible electrochemical systems represented by 2,4-dichlorophenol (DCP), hydroquinone (HQ) and K3 [Fe(CN)6 ], respectively, were investigated on a CdS-graphene hybrid film electrode. The cyclic voltammetric (CV) curves of HQ and K3 [Fe(CN)6 ] showing a pair of redox peaks became sigmoidal in shape under visible light irradiation. In contrast, the CV curve shape of DCP showing an oxidation peak was not changed under photoirradiation, although the oxidation peak current was enhanced by the photoelectrocatalysis. Thus, the reversibility-dependent photovoltammetric behaviors were observed. Furthermore, it was demonstrated that the photovoltammetric curve shapes were not changed by pH and intensity of light source, but were tunable with scan rate and concentration of reactants depending on the reversibility of the electrochemical reactions.