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IPM
30
YEARS OLD

“School of Nano-Sciences”

Paper   IPM / Nano-Sciences / 15802
   School of Nano Science
  Title: Two-dimensional SiX2 (X=P,As) as a promissing photocatalyst for water splitting: a computational study
  Author(s):
1 . Fazel Shojaei
2 . Bohayra Mortazavi
3 . Xiaoying Zhuang
4 . Maryam Azizi
  Status: Submitted
  Journal:
  Year: 2019
  Supported by: IPM
  Abstract:
Photocatalytic hydrogen production via water splitting over two dimensional (2D) materials as light absorber semiconductor is a promising solution to the energy crisis and environmental pollutions. By using density functional theory computations, we introduced SiX2 (X = P, As) monolayers in pentagonal and orthorhombic phases to be promising light absorber semiconductors for water splitting. The monolayers exhibit good dynamic and thermal stability. They have small cleavage energies of in the range of 0.31 J/m2 to 0.39 J/m2 , comparable to that of graphene, indicating their feasible experimental exfoliation. All the monolayers are semiconductors with indirect band gaps of 2.65 eV for penta-SiP2, 2.35eV for penta-SiAs2, 1.89 eV for rec-SiAs2, and a direct band gap of 2.21 eV for rec-SiP2 systems. The materials show relatively large interlayer quantum confinement effects, resulting in smaller band gap values for bilayer structures. We observed a huge difference between the mobilities of electrons and holes in penta-SiP2 and rec-SiAs2 monolayers and highly directional electron and hole mobilities in rec-SiP2, result in an effective separation of photogenerated electrons and holes. The monolayers also show suitable band edge positions for photocatalytic water splitting reaction, specifically under neutral condition.

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