Two-dimensional MgAl2S4 as potential photocatalyst for water splitting and strategies to boost its performance

Exploring novel 2D water-splitting photocatalysts and finding strategies to boost their efficiency are important tasks in nowadays energy industry. Here, employing first-principle calculations, we predicted a novel 2D material, MgAl 2 S 4 monolayer, and studied its potential applications in photocatalytic water splitting. 2D MgAl 2 S 4 is noble-metal-free and possesses great thermal and dynamical stability. The cleavage energy is around 16 meV/Å 2 which is even lower than graphene, indicating the high feasibility for experimental fabrications. The band edge positions and the optical absorption spectra indicate the pristine MgAl 2 S 4 monolayer can work as a photocatalyst upon ultraviolet irradiation. Its high electron mobility around 745 cm 2 v -1 s −1 and high conduction band minimum (CBM) position suggest a strong reduction ability. Furthermore, the oxidation ability and light absorbance can be significantly enhanced by a small tensile strain. The complementary marriage of MgAl 2 S 4 and SnSe 2 monolayers can form a direct z-scheme heterostructure, which can fully utilize the photocatalytic potential of both components.