Porphyrin 'Mille-Feuilles' photo-electrodes

A porphyrin ‘‘Mille-Feuilles” photo-electrode is fabricated layer-by-layer by deposition of anionic [zinc meso-tetrakis(p-sulfonato phenyl) porphyrin]4- (ZnTPPS4−) and positively charged polypeptides on a 11-mercaptoundecanoic acid-modified gold electrode to form a photoactive film. This work demonstrates that it is possible to form 3D structures having regularly spaced layers of redox molecules. UV–visible spectra of the multilayer films display the characteristic absorption bands of the porphyrins and the absorbance increases linearly with the number of bilayers. The cyclic voltammetric response of the films in contact with 1,2-dichloroethane (DCE) varies from that of a modified electrode to that of a supported liquid film. Under illumination, a large photocurrent response for oxygen reduction with a maximum for a 5-bilayer film is observed.