First principles calculation of the ZnV₂O₆(001) surface terminations: the thermodynamic stability and electronic...

We have investigated the surface structure and relative stability of ZnV₂O₆(001) using a thermodynamic technique based on density functional theory (DFT). We built Zn-V-O surface phase diagrams of various surface terminations using the obtained surface Gibbs free energy. In this study, we selected nine different surface terminations along the (001) crystal plane to elucidate that the E, G, H, and I terminations (as shown in Table 1) are the most stable configurations. We found that although their stability varies widely, the four terminations on the ZnV₂O₆(001) surface can be stabilized under specific thermodynamic equilibrium circumstances. Furthermore, we calculated the surface electronic structures of the four surface terminations and found that there are surface states conducive to visible light absorption at the G, H, and I terminations. The different termination structures are significant in improving the range and intensity of light absorption of ZnV₂O₆ in specific regions. The fact that the work functions fluctuate significantly for different surface terminations suggests that the work function of ZnV₂O₆ can be changed to increase photocatalytic activity by achieving thermodynamically favored surface terminations under appropriate conditions. The obtained surface phase diagram will further lay a foundation for the study of the ZnV₂O₆ surface. These results may help to explore the inherent properties of the ZnV₂O₆ surface and provide useful strategies for future experimental research on ZnV₂O₆-based photocatalysts.