LAUSR

Abstract PtSe2 monolayer is previously predicted to be a two-dimensional water-splitting photocatalyst. However, the weak van der Waals (vdW) interaction between H2O and the basal surface of PtSe2 significantly undermines its photocatalytic water-splitting activities. In this work, we explore the possibility of various intrinsic defects of PtSe2 in remedying this deficiency on the basis of first-principles calculations. It is interesting to find that the introduction of Pt@Se, Se@Pt, and Se interstitial defect not only fully retain the water redox abilities of pure PtSe2 and realize spatial separation of photogenerated electrons and holes, but also can extend optical absorption range and absorption coefficients. Moreover, introduction of the three kinds of defects increase the initial weak vdW interactions between H2O and the PtSe2 surface to different extent. In particular, Pt@Se anti-site defect transform the initial weak vdW to strong chemical interaction between H2O and PtSe2 surface, and function as active reaction site. These insights demonstrate that introduction of intrinsic defects, especially the Pt@Se anti-site defect, are effective means for improving the photocatalytic water-splitting activities of PtSe2 monolayer.