Two-dimensional TiNBr as photocatalyst for overall water splitting

Two-dimensional (2D) Janus materials gain increasing attention as water splitting photocatalysts for hydrogen production. We use first-principles calculations to predict a stable 2D Janus $T$-TiNBr structure, with strong near-ultraviolet sunlight absorption and band edges that align favorably with the water redox potentials for oxygen and hydrogen evolution. We show that the optical and electronic properties of $T$-TiNBr can be modulated to a certain extend by applying external uniaxial strain. Explicit calculations of the redox reactions reveal that solar-driven water splitting is viable at the N-side of $T$-TiNBr, while the Br-side requires modifications such as vacancy creation, the application of an external potential, or adjustment of the pH conditions.