Controllable Growth of MoS2 on Au Foils and Its Application in Hydrogen Evolution

Controllable synthesis of monolayer MoS2 on metal substrates is the basic premise for exploring the intrinsic electronic structure, some novel physical properties, and engineering its application in hydrogen evolution reaction (HER). In recent years, we have been working on low-pressure chemical vapor deposition (LPCVD) growth of monolayer MoS2 on Au foils, with the domain size can be tuned from several hundred nanometers to dozens of microns. By introducing H-2 as carrier gas, we have synthesized large domain monolayer MoS2 triangular flakes on Au foils, with the edge length approaching to ca. 81 mu m. By using low-energy electron microscopy/diffraction (LEEM/LEED) method, the crystal orientations and domain boundaries of monolayer MoS2 flakes directly on Au foils are further on-site identified. Of particular interest, the nanosized MoS2 flakes on Au foils are proven to be excellent electrocatalysts for HER, featured by a rather low Tafel slope (ca. 61 mV/dec) and a relative high exchange current density (ca. 38.1 mu A/cm(2)). In this review, we summarized controllable growth and on-site domain boundary imaging of monolayer MoS2 on Au foils and its application in HER together with a brief discussion on the future directions, challenges and opportunities in this research area.