Photocatalytic Electron and Proton Pumping across Conducting Polymer Films Loaded with Semiconductor Particles

Polyaniline and polyanion-doped polypyrrole films were demonstrated to have preferential permeability for ions, especially for protons. Transport of electrons and ions through these conducting polymer films was also demonstrated by utilizing the difference of electrochemical potentials of the solutions placed across the films. On the basis of these properties of the conducting polymer films, photocatalytic electron- and proton-pumping systems were constructed, in which conducting polymer films loaded with titanium dioxide or cadmium sulfide particles on one side of the film surfaces were utilized. By photoirradiation of the semiconductor particles, 2-propanol was oxidized on the semiconductor particles and iron(III) ions were reduced on the other surface of the conducting polymer films. Along with the electrochemical reactions, electrons and ions were cotransported across the conducting films. Protons were concluded to be the chief ionic carrier under the acidic conditions.