Low-dimensional semiconducting materials with moderate band gap as well as high carrier mobility are highly sought for future microelectronics.By means of the hybrid density functional theory computations,we predicted that a novel two-dimensional(2D)Ⅳ-Ⅵ material,namely germanium monosulfide(GeS)monolayer,is a rather desirable candidate.According to our computations,GeS monolayer is semiconducting with an indirect band gap of 2.34 eV,which can be effectively tuned by employing an external strain.Remarkably,GeS monolayer has an electron mobility of 3680 cm2/Vs,which is much higher than that of MoS2 monolayer.Our computations also revealed that GeS monolayer is a stable structure and can be obtained by exfoliation or mechanical cleavage techniques.These findings render GeS monolayer a promising 2D material for applications in future microelectronic,and call for more research attentions on 2D Ⅳ-Ⅵ materials.