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<p>A comprehensive first-principles investigation of K<sub>2</sub>NaX (X = S, Se, Te) Janus monolayers was conducted to evaluate their suitability for photocatalytic water splitting. Structural optimization confirms the stability of the proposed monolayers, with negative formation and cohesive energies indicating favorable energetic stability. Dynamical stability is verified by phonon spectra free of imaginary frequencies, while ab initio molecular dynamics simulations at 300&#xa0;K demonstrate thermal robustness. The calculated elastic constants satisfy the Born–Huang criteria, confirming mechanical stability. HSE06 calculations reveal direct band gaps of 2.19, 2.16, and 2.06&#xa0;eV for K<sub>2</sub>NaS, K<sub>2</sub>NaSe, and K<sub>2</sub>NaTe, respectively. Their band-edge positions appropriately straddle the water redox potentials at pH 7, enabling spontaneous overall water splitting. GW-BSE calculations predict strong visible-light absorption with absorption coefficients up to 1.13 × 10⁶ cm⁻¹. High solar-to-hydrogen efficiencies ranging from 28.47% to 41.95% highlight the excellent potential of K₂NaX monolayers for solar hydrogen production.</p>

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Visible-light active K2NaX Janus monolayers: electronic structure and photocatalytic insights

  • 期刊论文

  • 发表日期：

    2026年6月22日

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  • Mohamed El Amine El Goutni,
  • Hela Ferjani,
  • Mohammed Batouche,
  • Walid Belhadj,
  • Yasmeen G. Abou El-Reash,
  • Mohamed Houcine Dhaou

摘要

A comprehensive first-principles investigation of K2NaX (X = S, Se, Te) Janus monolayers was conducted to evaluate their suitability for photocatalytic water splitting. Structural optimization confirms the stability of the proposed monolayers, with negative formation and cohesive energies indicating favorable energetic stability. Dynamical stability is verified by phonon spectra free of imaginary frequencies, while ab initio molecular dynamics simulations at 300 K demonstrate thermal robustness. The calculated elastic constants satisfy the Born–Huang criteria, confirming mechanical stability. HSE06 calculations reveal direct band gaps of 2.19, 2.16, and 2.06 eV for K2NaS, K2NaSe, and K2NaTe, respectively. Their band-edge positions appropriately straddle the water redox potentials at pH 7, enabling spontaneous overall water splitting. GW-BSE calculations predict strong visible-light absorption with absorption coefficients up to 1.13 × 10⁶ cm⁻¹. High solar-to-hydrogen efficiencies ranging from 28.47% to 41.95% highlight the excellent potential of K₂NaX monolayers for solar hydrogen production.