Two-Dimensional CuTe2X (X = Cl, Br, and I): Potential Photocatalysts for Water Splitting under the Visible/Infrared Light

Exploring new two-dimensional (2D) materials with excellent light absorption ability is important for efficient photocatalytic water splitting. In this work, we systematically studied the mechanical, electronic, and optical properties of an unexplored class of 2D material (CuTe2Cl, CuTe2Br, and CuTe2I monolayers) by density functional theory (DFT) calculations. We find that CuTe2X monolayers with great thermal and dynamic stability can be easily exfoliated from their bulk phases. CuTe2X monolayers possess band gaps of 1.7-1.8 eV and their band edge positions bestride the water oxidation and reduction potential. Moreover, they exhibit extraordinary light harvesting ability in both visible and near-infrared regions. Thus, CuTe2X monolayers would be promising photocatalysts for water splitting. In addition, their strain-tunable electronic structure can further improve their photocatalytic capability. Our work not only expands the family of 2D materials but also highlights new interesting materials for solar hydrogen production.