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<p>This study explores the vacancy-ordered double perovskites A<sub>2</sub>RuBr<sub>6</sub> (A = Cs, Rb, K) as novel photocatalysts and spintronic materials, addressing the global climate crisis through sustainable oxidation processes. Employing density functional theory (DFT) with the Wu-Cohen Generalized Gradient Approximation (GGA-WC), Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, and spin-orbit coupling (SOC) within the WIEN2k package, we investigate their structural, electronic, optical, and mechanical properties. Structural analyses reveal a stable cubic Fm-3&#xa0;m lattice with lattice constants of 10.23–10.58 Å, bulk moduli of 32.06–37.46 GPa, and negative formation energies (–2.61 to − 3.57&#xa0;eV), confirming thermodynamic and mechanical stability. Electronic properties exhibit direct band gaps of 1.50–1.68&#xa0;eV (λ ≈ 738–826&#xa0;nm), enabling efficient absorption deep into the visible-red region and covering ~ 30–35% of the solar spectrum, significantly higher than TiO<sub>2</sub> (Eg ≈ 3.2&#xa0;eV, λ ≈ 388&#xa0;nm, ~ 5%) and CdS (Eg ≈ 2.4&#xa0;eV, λ ≈ 517&#xa0;nm, ~ 17%). Half-metallic ferromagnetic behavior driven by Ru 4d electrons enhances spin-polarized transport. Optical characteristics include high absorption coefficients (4.25–7.34 × 10<sup>5</sup> cm<sup>−1</sup>), low reflectivity (10–14%), and excitonic binding energies of 139–167 meV, promoting efficient charge separation. Band edge positions (EVB: 1.69–1.75&#xa0;eV; ECB: 0.01–0.25&#xa0;eV) favor water oxidation, surpassing TiO<sub>2</sub>, CdS, and WO<sub>3</sub> in visible-light responsiveness and spin selectivity, though reduction is limited by positive ECB. Mechanical ductility (B/G &gt; 1.88) supports durability. Future research on stability enhancements and experimental validation is essential to realize A<sub>2</sub>RuBr<sub>6</sub>’s potential in sustainable energy applications.</p>

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Vacancy-ordered A2RuBr6 double perovskites as dual-functional visible-light photocatalysts and half-metallic spintronic materials

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  • 发表日期：

    2026年7月10日

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  • Mohamed El Amine El Goutni,
  • Danish Abdullah,
  • Mohammed Batouche,
  • Hela Ferjani,
  • Taieb Seddik,
  • Aarif Ul Islam Shah,
  • Edson L. Meyer

摘要

This study explores the vacancy-ordered double perovskites A2RuBr6 (A = Cs, Rb, K) as novel photocatalysts and spintronic materials, addressing the global climate crisis through sustainable oxidation processes. Employing density functional theory (DFT) with the Wu-Cohen Generalized Gradient Approximation (GGA-WC), Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, and spin-orbit coupling (SOC) within the WIEN2k package, we investigate their structural, electronic, optical, and mechanical properties. Structural analyses reveal a stable cubic Fm-3 m lattice with lattice constants of 10.23–10.58 Å, bulk moduli of 32.06–37.46 GPa, and negative formation energies (–2.61 to − 3.57 eV), confirming thermodynamic and mechanical stability. Electronic properties exhibit direct band gaps of 1.50–1.68 eV (λ ≈ 738–826 nm), enabling efficient absorption deep into the visible-red region and covering ~ 30–35% of the solar spectrum, significantly higher than TiO2 (Eg ≈ 3.2 eV, λ ≈ 388 nm, ~ 5%) and CdS (Eg ≈ 2.4 eV, λ ≈ 517 nm, ~ 17%). Half-metallic ferromagnetic behavior driven by Ru 4d electrons enhances spin-polarized transport. Optical characteristics include high absorption coefficients (4.25–7.34 × 105 cm−1), low reflectivity (10–14%), and excitonic binding energies of 139–167 meV, promoting efficient charge separation. Band edge positions (EVB: 1.69–1.75 eV; ECB: 0.01–0.25 eV) favor water oxidation, surpassing TiO2, CdS, and WO3 in visible-light responsiveness and spin selectivity, though reduction is limited by positive ECB. Mechanical ductility (B/G > 1.88) supports durability. Future research on stability enhancements and experimental validation is essential to realize A2RuBr6’s potential in sustainable energy applications.