Janus γ-GeSSe Monolayer as a High-Performance Material for Photocatalysis and Thermoelectricity

Vuong Van Thanh, Do Van Truong, Nguyen Tuan Hung

Research output: Contribution to journalArticlepeer-review


Two-dimensional Janus materials have attracted increasing attention in recent years because of their potential as materials for energy applications, such as photocatalysis and thermoelectricity (TE). Here, for the first time, we propose a monolayer Janus structure with the Mexican-hat band, γ-GeSSe, by replacing the S atoms on one side of the synthesized γ-GeS with Se atoms. Using first-principles calculations based on density functional theory (DFT), we show that γ-GeSSe is mechanically, dynamically, and thermally stable. The mechanical, electronic, optical, and transport properties of monolayer Janus γ-GeSSe are also investigated in the DFT calculations. We find that the ideal strengths of the Janus γ-GeSSe are 6.08, 8.6, and 10.08 GPa for the armchair, zigzag, and biaxial directions, respectively. The Janus γ-GeSSe is an indirect-gap semiconductor with a band gap of 1.131 eV. Our results show the Janus γ-GeSSe as a photocatalysis material for water splitting with a high solar-to-hydrogen efficiency of up to 28.78%. This is because the combination of features includes an intrinsic electric field, high optical absorption coefficient, and carrier mobility. In addition, with the γ-structure, the Janus γ-GeSSe shows an intrinsic low lattice thermal conductivity of 3.33 W/mK at room temperature, which will contribute to obtaining high TE efficiency. By using the Boltzmann transport theory, we find that the maximum TE power factor and figure of merit of the Janus γ-GeSSe reach 55-85 mW/mK2 and 0.7-0.9 in the temperature range from 300 to 900 K, respectively. Thus, our findings not only contribute to proposing a Janus material but also suggest that it can be used as an energy material with high-performance photocatalysis and TE.

Original languageEnglish
Pages (from-to)910-919
Number of pages10
JournalACS Applied Energy Materials
Issue number2
Publication statusPublished - 2023 Jan 23


  • Janus monolayer
  • density functional theory
  • ideal strength
  • photocatalysis
  • thermoelectricity

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering


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