Understanding the Structural, Electrical, and Optical Properties of Monolayer h-phase RuO2 Nanosheets: A Combined Experimental and Computational Study

Abstract: The structural, electrical, and optical properties of monolayer ruthenium oxide (RuO2) nanosheets (NSs) fabricated using chemical exfoliation of layered three-dimensional forms of K- and Na-intercalated RuO2 are studied systematically via experimental and computational methods. Monolayer RuO2 NSs is identified to have distorted h-MX2 structures. This is the first observation of a RuO2 NS structure that is not similar to the t-MX2 structure of the RuO2 layers in the parent materials and does not have hexagonal symmetry. These distorted h-MX2 RuO2 NSs are shown to have optical transparencies superior to that of graphene, thereby predicting the feasibility of applying RuO2 NSs to flexible transparent electrodes. In addition, it is demonstrated that the semiconducting band structures of RuO2 NSs can be manipulated to be semi-metallic by adjusting the crystal structure, which is related to band-gap engineering. This finding indicates that the RuO2 NSs can be used in a variety of applications, such as flexible transparent electrodes, atomic layer devices, and optoelectronic devices.