All-Solid-State Z-scheme Ta3N5/Bi/CaTaO2N photocatalyst transformed from perovskite CaBi2Ta2O9 for efficient overall water splitting

Building up of all-solid-state Z-scheme system is vital to enhance the photoexcited charge separation and avoid the backward reactions for photocatalytic water splitting. However, coupling two individual photocatalysts with an electron mediator by a one-pot strategy is still a challenge. Here, an all-solid-state Z-scheme Ta3N5/Bi/CaTaO2N photocatalyst is successfully fabricated for the first time through a simple one-step nitridation approach. Density functional theory calculation and experimental results prove that CaTaO2N and Ta3N5 are employed as a H2-evolving and an O2-evolving photocatalyst, respectively. In-situ formed metallic Bi acts as an electron mediator for charge transfer between Ta3N5 and CaTaO2N, facilitating an improvement of the photogenerated charge separation efficiency. Therefore, in the absence of a sacrificial agent, Ta3N5/Bi/CaTaO2N exhibits an excellent photocatalytic overall water splitting performance under visible light irradiation. Meanwhile, an apparent quantum efficiency as high as 0.42% at 420 ± 15 nm is achieved, which surpasses most of the reported tantalum-based (oxy) nitrides photocatalysts. This work provides a new strategy for fabricating highly efficient and stable all-solid-state Z-scheme photocatalyst for solar energy conversion.