Stable photocatalysts with excellent optical adsorption and low reaction barrier are the key for the water splitting. Here, we find that a two-dimensional Janus WSSe monolayer possesses the compelling photocatalytic properties from density functional theory simulations, which can be well modulated with strain deformation. Comprehensive investigations indicate that the Janus material not only exhibits strong optical absorbance in the visible spectrum, suitable band edge potentials, high carrier separation, and transfer efficiency but also has adequate driving forces of photoexcited carrier for water redox reaction and good resistance against photoinduced corrosion. Janus WSSe is therefore predicted to be a promising photocatalyst for water splitting. Moreover, we also find that tensile strains could further improve the photocatalytic performance for water splitting by effectively increasing the energy conversion efficiency and reducing the exciton binding energy. Our results not only predict a photocatalyst, which can utilize the visible light for overall water splitting, but also propose an effective path to extend the absorption spectra and raise the photocatalytic efficiency.

Photocatalytic water splitting is a promising technology to solve the energy crisis and provide renewable and clean energies. Recently, although numerous 2D materials have been proposed as the photocatalytic candidates, the strategies to effectively modulate photocatalytic reactions and conversion efficiency are still lacking. Herein, based on first-principles calculations, we show that the photocatalytic activities and energy conversion efficiency can be well tuned by ferroelectric–paraelectric phase transition of a AgBiP2Se6 monolayer. It is found that the AgBiP2Se6 monolayer has a higher potential and driving forces of photogenerated holes for water oxidation in the ferroelectric phase, but higher corresponding values of photogenerated electrons for the hydrogen reduction reaction in the paraelectric phase. Besides, the solar-to-hydrogen energy conversion efficiency is also tunable with the phase transition; it is up to 10.04% at the ferroelectric phase due to the better carrier utilization, but only 6.66% at the paraelectric phase. Moreover, the exciton binding energy is always smaller in the paraelectric state than that in the ferroelectric state, indicating that the ferroelectric switch could also make a directional adjustment to the photoexcited carrier separation. Our theoretical investigation not only reveals the importance of ferroelectric polarization on water splitting, but also opens an avenue to modify the photocatalytic properties of 2D ferroelectric materials via a ferroelectric switch.

Due to the presence of intrinsic polarization, Janus MoSSe is proposed as an ideal material for controllable ultrahigh-sensitive sensors.

Toxic gas detection and capture are two important topics, which are highly related with human health and environments. Recently, theoretical simulations based on first‐principles calculations have suggested two‐dimensional (2D) materials to be as ideal candidates for gas sensing and capturing due to the large surface–volume ratio and reactive surface. Starting from graphene, which was firstly proposed for 2D gas sensing, the family currently has been extended to transition metal dichalcogenides, phosphorene, silicene, germanene, MXene, and so on. In this review, we give a comprehensive overview of recent progress in computational investigations of 2D gas sensing/capture materials. We then offer perspectives on possible directions for further fundamental exploration of gas sensor and caption based on 2D materials, which are expected to offer tremendous new opportunities for future research and development. This article is categorized under: Structure and Mechanism > Computational Materials Science