Fabrication of efficient TaON and Ta3N5 photoanodes for water splitting under visible light irradiation

Efficient TaON and Ta3N5 photoanodes for water splitting were fabricated on conducting glass support (FTO). A necking treatment, which forms effective contacts between TaON (or Ta3N5) particles, afforded a significant increase in the photocurrent. Furthermore, loading of IrO2 center dot nH(2)O nanoparticles as a cocatalyst for water oxidation improved the photocurrent of the TaON (or Ta3N5) photoanode. The incident photon to charge carrier efficiencies (IPCEs) of the TaON and Ta3N5 photoanodes were calculated to be ca. 76% at 400 nm and ca. 31% at 500 nm, respectively, at 1.15 V vs. reversible hydrogen electrode (RHE) in aqueous Na2SO4 solution. Overall water splitting into H-2 and O-2 under visible light was demonstrated using an IrO2 center dot nH(2)O-loaded TaON (or Ta3N5) photoanode combined with a Pt electrode under an externally applied bias (TaON: > 0.6 V, Ta3N5: > 1.0 V).