In this study, we investigated Janus and alloy structures of PtXnY(2-n) (X,Y=S,Se,Te; 0≤n≤2) materials on the basis of first-principles plane-wave simulations. Using cluster expansion theory for studying alloys of PtXnY(2-n) monolayers at various concentrations, for half coverage (n=1), our results indicated that Janus type structures are not energetically the most favorable for PtXY monolayers, however they are dynamically and thermally stable. In order to distinguish Janus PtXY structures, we reported the Raman active modes and compared them with bare PtX2 monolayers. Calculated electronic band gap values using hybrid functionals are on-par with available experimental data. It is also reported that spin-orbit coupling significantly modified the electronic band structure of PtXY monolayers. Due to the electronegativity differences of different chalcogen atoms on each surfaces of Janus PtXY structures, the arising dipole moment significantly modified the band alignments on both surfaces. We found that hydrogen evolution and oxygen reduction happen on different surfaces and applied strain enhanced the catalytic activity. Our results indicated that due to their intrinsic dipole moments and band gaps, Janus PtXY monolayers are the perfect candidates for water splitting reactions.

Exploring PtXnY(2-n) (X, Y= S, Se and Te ; 0≤n≤2) monolayers: Is Janus PtXY the most favorable one?

2019 Spring National Meeting

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