Janus Chromium Dichalcogenide Monolayers with Low Carrier Recombination for Photocatalytic Overall Water-Splitting under Infrared Light

Photocatalytic overall water-splitting is known as one of most promising methods to alleviate energy crisis. Searching for stable and efficient photocatalysts plays a critical role in this process. Here, we propose a novel class of Janus chromium dichalcogenide (CrXY, X/Y = S, Se, and Te) monolayers serving as efficient photocatalysts for overall water-splitting under infrared light irradiation. We reveal that these Janus monolayers harbor an intrinsic dipole, which promotes the spatial separation of photogenerated carriers. More significantly, these systems exhibit suitable band gaps as well as band edge positions, enabling preeminent infrared optical absorption and high carrier mobility. Furthermore, the nonradiative recombination of photo induced charge carriers in CrXY monolayers is evaluated based on time domain density functional theory. The obtained long-lived excited carriers ns) are even comparable with that in transition-metal dichalcogenide heterostructures, which benefits for the photocatalytic reaction with high efficiency. Our results provide a new guidance for designing brand new photocatalytic systems with broad optical absorption and low carrier recombination.