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

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.