Understanding the thermodynamic, dynamic, bonding, and electrocatalytic properties of low-dimensional MgPSe 3 .

The study of novel two-dimensional structures for potential applications in photocatalysis or in optoelectronics is a challenging task. In this work, first-principles calculations have been carried out to explore the properties of the two-dimensional perovskite-based MgPSe 3 . Dynamic and mechanical analyses confirm the stability of this low-dimensional material. Our calculated Raman frequencies are in good agreement with previous studies. Furthermore, a topological bonding analysis, based on the electron localization function, indicates a covalent and ionic character for the P-Se and Mg-Se bonds, respectively. From a reactivity point of view, water interacts poorly with MgPSe 3 and its associative interaction is physisorbed and governed by weak interactions. Consequently, the low dissociative energy of H 2 O molecules affects the reaction taking place on the surface of the material, making it unfavorable for both hydrogen and oxygen evolution reactions. However, the computed electronic properties show that MgPSe 3 is a promising material for optoelectronic applications.