Controlled Synthesis and Phase Transition Mechanisms of Palladium Selenide: A First-Principles Study.

Abstract

Using density functional theory, we carefully calculated the relative stability of monolayer, few-layer, and cluster structures with Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃-phase. We found that the stability of Penta PdSe₂ increases with the number of layers. The Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃ monolayers are all semiconducting, with band gaps of 1.77, 0.81, and 0.65 eV, respectively. The formation energy of palladium selenide clusters with different phase structures is calculated, considering the cluster size, stoichiometry, and chemical environment. Under typical experimental conditions, Pd₂Se₃ phase clusters are found to be dominant, having the lowest formation energy among all of the phases considered, with this dominance increasing as cluster size grows. Adjusting the Pd-Se ratio in the environment allows for controlled synthesis of specific palladium selenide phases, providing theoretical insights into the nucleation mechanisms of PdSe₂ and other transition metal chalcogenides.