Expediting photocarrier separation in Ta₃N₅@CaTaO₂N heterostructures with seamless interfaces for photocatalytic water oxidation under visible light

The separation of photocarriers (e^- and h⁺) is of critical importance in initiating efficient catalytic reactions over semiconductor-based photocatalysts. Although heterostructures have been frequently built to separate photocarriers, the lack of proper heterogeneous interfaces greatly limits their efficacies. Here, we show that excellent heterogeneous interfaces can be built for in situ fabricated Ta₃N₅ @CaTaO₂N heterostructures. These interfaces are characterized by perfectly matching (020) crystal facets of Ta₃N₅ and CaTaO₂N, offering ideal channels for charge transportation. As revealed by both experimental and theoretical analysis, these seamless interfaces enable rapid spatial photocarrier separation, which in turn, contribute to exceptional photocatalytic activity. Under optimal conditions, Ta₃N₅ @CaTaO₂N heterostructures achieve apparent quantum efficiency as high as 14.52% at 420 ± 20 nm for O₂-evolution, substantially surpassing Ta₃N₅, CaTaO₂N, and their mixtures. These results not only justify the importance of heterogeneous interfaces for photocarrier separation but also invigorate more attention upon heterostructures towards efficient solar water splitting.