Transition Metal-Functionalized Janus MoSSe Monolayer: A Magnetic and Efficient Single-Atom Photocatalyst for Water Splitting Applications

Janus MoSSe monolayers are recently proposed as a potential water-splitting photocatalyst. However, the weak van der Waals (vdW) interaction between water molecules and the surfaces of MoSSe significantly inhibits the photocatalytic efficiency. On the basis of first-principles calculations, in this work, we explore the possibility of single-atom functionalization in remedying this deficiency of MoSSe. Specifically, we investigate the single atom adsorption effects of first row Sc-Zn transition metal (TM) elements on the interaction mechanism between the water molecule and MoSSe and on the other intrinsic properties of MoSSe as a water-splitting photocatalyst. It is found that all the TMs except Zn can adsorb strongly and chemically on both S and Se sides of MoSSe, and the initial weak vdW interaction between H2O and pure MoSSe is successfully transformed into strong chemical interactions in the TM-modified MoSSe, where TMs play the role of very active sites for photo-catalyzing water-splitting. Additionally, other intrinsic properties of MoSSe, such as intrinsic dipole and optical absorption, are further improved by proper TM adsorption, suggesting higher solar conversion efficiency. Astonishingly, all the TM-modified MoSSe except for Ni are magnetic, rendering them magnetic photocatalysts; this is not only beneficial for efficient recycling of the photocatalysts but also suggests potential applications of them in spintronics. Our work demonstrates the potential role of single-atom functionalization technology in improving and enriching the intrinsic properties of two-dimensional monolayer materials for photocatalytic and electronic applications.