Enhanced optical and electronic properties of a solar light-responsive photocatalyst for efficient hydrogen evolution by SrTiO3/TiO2 nanotube combination

• Versatile SrTiO3/TiO2 nanotube composite was prepared by hydrothermal method.
• The detailed formation mechanism of SrTiO3/TiO2 nanotube was provided.
• Using SrTiO3/TiO2 nanotube as the internal layer material facilitated e− delivery.
• Multi-junction photocatalyst also exhibited excellent visible light response.
• The optimal H2 evolution rate of multi-junction photocatalyst was 3513 μmol/h/g.

Strontium titanate/titanium dioxide nanotube composite (SrTiO3/TiO2 nanotube) exhibiting electronic delivery and visible light response was prepared by a facile hydrothermal method. Versatile multi-junction photocatalysts composed of SrTiO3/TiO2 nanotube, N-doped TiO2, and platinum (Pt) as the internal, middle, and outer layer materials, respectively, were successfully developed in this study. The excellent electronic delivery of TiO2 nanotube and redox potential differences among N-doped TiO2, SrTiO3, and TiO2 nanotube facilitated the migration of photogenerated electrons from the bulk to the surface of the multi-junction photocatalysts, resulting in retarded charge recombination rates and increased H2 evolution rates. Moreover, because of their redox potential difference, the TiO2 nanotube and N-doped TiO2 could also provide their conduction band to accept excited electrons from the valence band of SrTiO3, leading to better visible light response. The optimal H2 evolution rate (3513 μmol/h/g) was achieved under simulated sunlight irradiation when the SrTiO3/TiO2 nanotube weight ratio and the Pt coating amount of the multi-junction photocatalyst were controlled to 5 wt.% and 0.2 wt.%, respectively.

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