PdSeO₃ Monolayer: Promising Inorganic 2D Photocatalyst for Direct Overall Water Splitting Without Using Sacrificial Reagents and Cocatalysts

Abstract

Direct production of H₂ from photocatalytic water splitting is a potential solution to environmental pollution and energy crisis, and tremendous efforts have been made to seek efficient photocatalysts that can split pure water (pH = 7) under visible light irradiation. Herein, by means of systematic density functional theory (DFT) computations, we demonstrated that the two-dimensional (2D) PdSeO₃ monolayer is a promising candidate. The mechanical exfoliation of PdSeO₃ monolayer from its bulk phase is experimentally feasible due to the rather small cleavage energy of ∼0.42 J/m². Remarkably, PdSeO₃ monolayer is semiconducting with a moderate indirect band gap of 2.84 eV, and its valence and conduction bands perfectly engulf the redox potentials of water. In particular, water oxidation and hydrogen reduction half reactions can both occur readily on the different active sites of PdSeO₃ monolayer under the potentials solely provided by photogenerated electrons and holes. As PdSeO₃ monolayer also has rather pronounced optical absorption in the visible and ultraviolet regions of the solar spectrum, it could be utilized as a highly efficient photocatalyst for splitting pure water into H₂ and O₂ in a stoichiometric amount of 2:1 without using sacrificial reagents or cocatalysts.