Two-dimensional Janus AgBiP2X3X3′ (X, X′ = S, Se, Te): Efficient intrinsic electric field regulatory strategy for photocatalytic overall water-splitting

Exploring highly efficient catalysts that utilize visible light for water-splitting shows immense potential in addressing energy and environmental challenges. However, most photocatalysts are faced with challenges such as low carrier migration ability, high carrier recombination rate, and insufficient driving force for water-splitting reactions. Here, based on the two-dimensional (2D) AgBiP2X6 (X = S, Se, Te) structures, we construct Janus AgBiP2X3X3′ (X, X′ = S, Se, Te) monolayers and theoretically investigate their photocatalytic performance. The results indicate that the Janus method effectively regulate the energy band structure and intrinsic electric field (EF) of the materials. The Janus AgBiP2S3Te3 structure possesses an optimal band gap and band edge position in comparison to AgBiP2X6. Among all the investigated materials, AgBiP2S3Te3 possesses the largest intrinsic EF. The vertical intrinsic EF in Janus AgBiP2S3Te3 facilitates spatial separation of photogenerated electrons and holes, allowing hydrogen evolution reaction (HER) to take place on its top surface and oxygen evolution reaction (OER) to occur on its bottom surface, thereby effectively preventing carrier recombination. The limiting potentials for OER and HER reactions are significantly reduced. The OER can proceeds spontaneously under neutral conditions. The Gibbs free energy change (ΔG) of the HER is 0.075 eV under acidic conditions at pH = 0, which closely approaches the optimal value of 0. Simultaneously, the Janus AgBiP2S3Te3 exhibits kinetic and thermal stability, suitable appfavorableropriate electron and hole mobility, and excellent visible light absorption capability. Our work not only predict a series of new 2D materials, but also paves a strategy for improving the photocatalytic properties of 2D ferroelectric materials.