Transition metal dichalcogenide monolayers have attracted extensive attention because of their rich physical and chemical properties and wide applications. In this work, we systematically investigate the electronic properties of tin dichalcogenide monolayers (SnX2, X = S, Se, and Te) and the effects of hydrogenation and tension by first-principles calculations based on the density-functional theory. We find that a pure SnX2 monolayer can be an intrinsic semiconductor or metal depending on the Sn–X bonding state. Hydrogenation can transfer its conductivity from a narrow-band semiconductor or a metal to wide-band semiconductor. We further show that a monolayer with a tunable band gap and even metallic characteristics can be achieved by applying tension. We predict that these tin-based dichalcogenide monolayers with controllable multi-functions may be employed in nanodevices and sensors.
