Unassisted Water Splitting from Bipolar Pt∕Dye-Sensitized TiO[sub 2] Photoelectrode Arrays

Direct photodecomposition of water to yield hydrogen and oxygen was achieved with bipolar photoelectrode panels, capable of vectorial electron transfer. This novel photoelectrochemical cell, which can overcome the problems of the location of the semiconductor bandedges relative to the water decomposition energy level and the requirement of dye and semiconductor stability during water decomposition in aqueous solution, splits water directly upon illumination without any additional energy input. The maximum hydrogen evolution efficiency of this system, based on the short-circuit current, was 3.7%.