(Invited) Nitride Photocatalyst to Produce Clean Hydrogen from Water without Extra Bias

Nitride semiconductors are attractive materials as clean energy devices. Nitride photocatalysts are possible to produce “clean hydrogen” from water using light energy. The nitride photoelectrode was immersed into a 1-M NaOH electrolyte with a Pt counterelectrode. There is no chemical bias which is caused by different pH solutions. Furthermore there is no extra bias between the nitride photoelectrode and Pt. A Xe lamp with 100 mW/cm² was used as a light source. The energy conversion efficiency from light energy to H₂ chemical energy was calculated using the Gibbs energy of H₂ combustion (-237.13 kJ/mol). The energy conversion efficiency for GaN photocatalyst was 1.4%. Continuous hydrogen generation was confirmed for 500 hours.