One chip photovoltaic water electrolysis device

We fabricated a photovoltaic water electrolysis device in which whole electrolyzing parts were formed on one chip. This was made by attaching the Co–Mo and the Fe–Ni–O electrodes for hydrogen and oxygen evolution, respectively, on the a-Si solar cell. Water electrolysis could be conducted simply by dipping and irradiating the device in electrolyte. The device was durable for more than 18 h electrolysis by irradiation in the KOH electrolyte at pH 13 at a conversion efficiency from solar to hydrogen energy of 2.5%.