Prediction of Co and Ru nanocluster morphology on 2D MoS(2) from interaction energies

Layered materials, such as MoS(2), have a wide range of potential applications due to the properties of a single layer, which often differ from the bulk material. They are of particular interest as ultrathin diffusion barriers in semiconductor device interconnects and as supports for low-dimensional metal catalysts. Understanding the interaction between metals and the MoS(2) monolayer is of great importance when selecting systems for specific applications. In previous studies the focus has been largely on the strength of the interaction between a single atom or a nanoparticle of a range of metals, which has created a significant knowledge gap in understanding thin film nucleation on 2D materials. In this paper, we present a density functional theory (DFT) study of the adsorption of small Co and Ru structures, with up to four atoms, on a monolayer of MoS(2). We explore how the metal–substrate and metal–metal interactions contribute to the stability of metal clusters on MoS(2), and how these interactions change in the presence of a sulfur vacancy, to develop insight to allow for a prediction of thin film morphology. The strength of interaction between the metals and MoS(2) is in the order Co > Ru. The competition between metal–substrate and metal–metal interaction allows us to conclude that 2D structures should be preferred for Co on MoS(2), while Ru prefers 3D structures on MoS(2). However, the presence of a sulfur vacancy decreases the metal–metal interaction, indicating that with controlled surface modification 2D Ru structures could be achieved. Based on this understanding, we propose Co on MoS(2) as a suitable candidate for advanced interconnects, while Ru on MoS(2) is more suited to catalysis applications.