Photoelectrochemical Tandem Cell with Bipolar Dye-Sensitized Electrodes for Vectorial Electron Transfer for Water Splitting

Direct water electrolysis was achieved with a novel monolithic photoelectrochemical cell. Bipolar W O 3 ∕ Pt and dye-sensitized Ti O 2 ∕ Pt semiconductor panels, capable of vectorial electron transfer, have been used for water splitting to yield hydrogen and oxygen; light is the only energy input. The hydrogen production efficiency of this tandem cell, based on the short-circuit current, was ∼ 1.9 % and the maximum hydrogen production efficiency was ∼ 2.5 % when 0.2 V positive bias was applied. When a concentrated LiCl aqueous solution was used as an electrolyte, valuable chlorine was obtained instead of oxygen. The maximum yielding efficiency of hydrogen and chlorine was ∼ 1.8 % .