Ta3N5 thin-film photoelectrodes were prepared using a reactive sputtering technique, and their properties for photoelectrochemical water splitting under visible light were investigated. The crystal phases of the films were dependent on the sputtering conditions, such as the N 2/O2 ratio of the sputtering atmosphere and the substrate temperature (Ts). Single-phase Ta3N5 films were obtained by sputtering at N2/O2 = 30 and Ts = 1013 K with post-annealing in an NH3 flow. The Ta3N 5 photoelectrodes had an anodic photoresponse in water photoelectrolysis, although the photocurrent rapidly decreased because of self-oxidation of the photoanode by photogenerated holes. However, modification of the NH3-treated Ta3N5 films with IrO 2 promoted the oxidation of water and suppressed the self-oxidation of Ta3N5.
- Surface modification
- Water splitting