Solar hydrogen production by water splitting using TiO2 based photoelectrodes

摘要

Photoelectrochemical water splitting into H2 and O2 was investigated using TiO2 based photoelectrodes. First, influence of photoelectorde structure on water splitting was studied through photocurrent observation. Solar energy conversion efficiency to H2 (STH) of mesoporous TiO2 photoelectode, composed of anatase TiO2 particles of 20nm in diameter, with 10μ thickness on FTO glass was 0.32% under 0.4V vs RHE, producing 0.39mA/cm2. The quantum efficiency of water splitting at 360nm was 27%. Then, visible light absorbing mesoporous N-doped and S-doped anatase TiO2 photoelectrodes were studied. Visible light absorbing properties of these photoelectrodes were dramatically decreased with increasing calcination temperature to 550°C. However, photocurrent such as 1μA/cm2 was observed under 0.94V vs RHE and visible light irradiation using 300W-Xe lamp with 410nm cut off filter. Overall photocurrent of N-doped and S-doped TiO2 photoelectrode was about 1/5 to 1/10 of that of non-doped TiO2 photoelectrodes. Finally, solar hydrogen production by a tandem cell, composed of a mesoporous TiO2 based photoelectrode, a Pt wire electrode and a Black dye-sensitized solar cell, was studied. STH of a non-doped TiO2 photoelectrode system was 0.53% but STH of a S-doped TiO2 photoelectrode system was 0.15%, which was 1/3 lower than that of a non-doped TiO2 photoelectrodes.