Thermodynamic stability and electronic structure properties of the Bi2WO6 (001) surface: first principle calculation

Abstract In this work, using a density functional theory (DFT)-based thermodynamic approach, we studied the stability of possible termination structures for the (0 0 1) surface of Bi2WO6. The Bi-W-O surface phase diagrams of the various surface terminations are constructed by obtained surface Gibbs free energies. We find that the five terminations of Bi2WO6 (0 0 1) surface can be stabilized under certain thermodynamic equilibrium conditions, though their stability is different significantly. Moreover, based on a hybrid functional, we calculate the five categories of surface termination's surface electronic structures. It is found that there are fat bands of the surface states in O W termination, which can contribute to visible light absorption. Therefore, an enhanced optical absorption in the visible light region is predicted in the O W termination. Furthermore, work functions are remarkably distinct for various surface terminations. This suggests that the direct Z-scheme heterostructure of Bi2WO6-based can be controlled by obtaining the thermodynamically preferred surface termination under suitable conditions. These results may help explore intrinsic properties for Bi2WO6 surfaces, providing a useful strategy for experimental studies of Bi2WO6-based photocatalyst in the future.