2D indium-VA semiconductors: Promising photocatalysts with intrinsic electric fields for water splitting

Exploration of two-dimensional (2D) semiconductors with intrinsic electric fields for photocatalytic applications has recently attracted great attention due to their prospective ability to inhibit the recombination of photo-generated carriers. Herein, employing first-principles calculations, we report a new group of 2D semiconductors, monolayer indium-VA (ML-InXs; X = P, As, and Sb), with intrinsic dipole as potential photocatalysts for water splitting. We systematically investigated the geometry, electronics and optics of ML-InXs, and identified their excellent structural stability, suitable band gaps, appropriate band edge positions, outstanding carrier transport and wide range of light absorption, which make them excellent photocatalysts for water splitting. More importantly, the electric field induced by the intrinsic dipole in ML-InXs would suppress the recombination of photogenerated electron-hole pairs, greatly enhancing the energy conversion efficiency during the photocatalytic reaction. In addition, we find that strain engineering can effectively tune the band gap and light absorption of ML-InXs and significantly enhance their solar-to-hydrogen efficiency for water splitting. Our results provide fundamental insight into the 2D photocatalysts with an intrinsic electric field and shed light on future design and modification of superior photo-catalysts for water splitting and other important chemical reactions.