Photocurrent Response of Polyaniline Film Electrode

Publisher Website
Google Scholar
Abstract
The photoelectrochemical behavior of polyaniline (PA) film was investigated in acidic aqueous solutions. In the presence of NO3− in the solutions, a large cathodic photocurrent was observed at lower potentials than 0.1 V vs. Ag/AgCl. The dependence of the current quantum efficiency at −0.1 V on the wavelength of light indicated that the photocurrent was due to the absorption of ultraviolet light by the reduced film of PA. The variations in potential and spectrum of the reduced film under open-circuit conditions confirmed the transformation of PA from a reduced state to a radical cation state with the ultraviolet irradiation. In conclusion, the cathodic photocurrent at −0.1 V could result from the photo-induced oxidation of the reduced PA film by NO3−. A film resistance-potential relationship was examined in connection with the pH dependence of the photoresponse of PA. The potential giving a minimum resistance at a given pH shifted to lower potentials with increasing pH. It can be presumed that a maximum in the photocurrent–pH curve arises from the increase in the ease of oxidation of the reduced film with an increase in pH.