Anisotropic and High-Mobility C3S Monolayer as a Photocatalyst for Water Splitting

Taking into account the high conductivity and stability of carbon materials, such as graphene, and the strong polar covalent bonding character of main-group compounds, we explore potential 2D materials in the C–S binary system through first-principles structure search calculations. Herein, a hitherto unknown semiconducting C3S monolayer is identified, consisting of well-known n-biphenyl and S atom linked benzenes, exhibiting an obvious direction-dependent atomic arrangement. Thus, it exhibits anisotropic mechanical properties and carrier mobility. Its electron mobility reaches 2.14 × 104 cm2 V–1 s–1 in the b direction, along which n-biphenyl units are arranged, and is much higher than that in the well-used MoS2 monolayer and black phosphorus. Meanwhile, the C3S monolayer has high optical absorption coefficients (105 cm–1), high thermal and dynamical stabilities, and a moderate ability to split water. All these desirable properties make the C3S monolayer a promising candidate for applications in novel optoelectronic devices.