Density Functional Theory Investigation of Direct Zscheme Cadmium Oxide /Blue Phosphorene Heterojunction

The urgent need for renewable energy solutions has driven research into advanced photocatalysts capable of efficiently harnessing solar energy. Z-scheme heterojunctions, known for their excellent charge separation and redox capabilities, have emerged as promising candidates. In this study, we constructed a two-dimensional Z-scheme heterojunction based on cadmium oxide (CdO) and blue phosphorene (BlueP). Using state-of-the-art density functional theory (DFT) simulations, we systematically investigated the structural, electronic, and photocatalytic properties of this heterojunction. The projected band (PBAND) structure reveals that the heterojunction exhibits a staggered band alignment. Specifically, the conduction band minimum (CBM) of CdO is lower than that of BlueP, while the valence band maximum (VBM) of BlueP is higher than that of CdO. This unique band structure enables an efficient transfer and recombination of photogenerated excitons between the CBM of CdO and the VBM of BlueP, while maintaining more reductive photoexcited electrons in the CBM of BlueP and more oxidative holes in the VBM of CdO layer. Moreover, the charge density distribution analysis demonstrates an interfacial built-in electric field from BlueP to CdO layer, further accelerating the exciton separation and migration. Consequently, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CdO} / \text{BlueP} \quad$</tex> Z-scheme heterojunction demonstrated enhanced charge separation efficiency and prolonged carrier lifetimes, which are essential for high photocatalytic activity. Our study highlights the potential of this material for advanced photocatalytic applications and provides a foundation for further exploration of two-dimensional Z-scheme heterojunctions in the pursuit of renewable energy solutions.