Photosensitized Effect of Water Soluble Porphyrins in Photochemical Cell Using an n-type Semicondoctor

Abstract

Using an n-type semiconductor(SnO
or In₂O₃) and a platinum electrode, photoelectrochemical study was carried out in water containing tetrakis(4-sulfophenyl)porphyrin as photosensitizer and L-ascorbic acid as electron donor. Under photoirradiation, photocurrent was observed, as a result of electron injection into the semiconductor electrode. Zn, Mn and metal free porphyrins were investigated, but photoreduction of them occurred. Subsequetly, porphyrin was immobilized on the surface of In₂O₃ electrode by poly(vinyl alcohol) cinnamate. As the result, porphyrin was protected from decomposition to a certain degree, and stabilization of photocurrent was observed. It was found that Zn and Mn porphyrins were particularly effective photocatalysts.