A composite of p-type poly(3-hexylthiophene-2,5-diyl) (P3HT) and n-type phenyl-C-61-butyric-acid-methyl ester (PCBM) was prepared and first applied to a photoelectrode in the water phase. The composite formed on a base electrode exhibited only photoanodic characteristics in the presence of an electron donor. Based on a microscopic image, the p/n composite formed at the substrate side and most of the P3HT maldistributed near the surface were responsible for the specified charge transfer. Supporting this morphology, the photoanodic characteristics were further enhanced by the combination of p-type zinc phthalocyanine (oxidation catalyst working in the dark) with the composite surface. (c) 2012 Elsevier B.V. All rights reserved.