Induced exfoliation by growing Cu1.96S nanoparticles on the edge defect sites of MoS2 and enhancing photothermal conversion

Abstract

The composite structures may integrate advantages of each species and afford new functionalized materials with fascinating properties for specific applications. In this study, a novel approach is proposed to prepare MoS2/Cu1.96S composite structures through shear-assisted exfoliation and edge-defect-assisted exfoliation. A simple relationship between the edge defect of MoS2 flakes, the growth of Cu1.96S and facilitating the exfoliation of MoS2 is proposed and supported by the experimental results. The shear-assisted exfoliation process facilitates the exfoliation of MoS2, which enables the growth of Cu1.96S at the edge defect sites of MoS2 flakes. As Cu1.96S forms at these sites, further exfoliation of MoS2 occurs, obtaining MoS2/Cu1.96S composite structures. The adsorption behavior of Cu atoms at different edge defect sites of MoS2 flakes is studied using density functional theory, and a growth model is proposed to explain the exfoliation mechanism of MoS2 flakes. Moreover, the prepared MoS2/Cu1.96S composite structures show higher photothermal conversion efficiency than MoS2 flakes. This improvement is attributed to lattice vibration arising from phonon emission and a pronounced extinction band caused by the collective oscillation of free holes induced by copper vacancies. This finding opens a new pathway towards for advanced fabrications of complex or composite structures.