Utilization of Perovskite-Type Oxynitride La_0.5Sr_0.5Ta_0.5Ti_0.5O₂N as an O₂-Evolving Photocatalyst in Z-Scheme Water Splitting

The particulate Z-scheme water splitting system involving a perovskite-type oxynitride as an O2-evolving photocatalyst has been first demonstrated using La0.5Sr0.5Ta0.5Ti0.5O2N accompanied by Ru-loaded SrTiO3:Rh and [Co(bpy)3]3+/2+ (bpy = 2,2′-bipyridine) as a H2-evolving photocatalyst and an electron mediator, respectively. O2 evolution was negligible when the bare oxynitride was employed. A Pt cocatalyst deposited on La0.5Sr0.5Ta0.5Ti0.5O2N promoted the reduction of [Co(bpy)3]3+ due to capturing electrons, resulting in an enhancement of O2 evolution. It has also been discovered that the [Co(bpy)3]3+/2+ electron mediator suppresses water formation over Pt particles.