A microwater vertical bar butyronitrile (W vertical bar BCN) interface was used to study the effect of the interfacial chemical polarization on the efficiency of the visible-light induced water oxidation reaction (WOR) by the electron acceptor/ photosensitizer TTF/TTF(center dot+)self-assembled on the surface of Co3O4 microparticles, acting as redox electrocatalysts. The polarized W|BCN interface acts as a selective platform for the separation of the products of the photoreaction, TTF and protons, which has a strong positive effect on the efficiency of the WOR. The resulting cobalt oxide-organic microwire junction is as efficient as its Pt analog.