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<p>This study comprehensively investigates the structural, electronic, optical properties, as well as the hydrogen storage potential, of the KH<sub>8</sub>N<sub>3</sub> hydride using first-principles calculations within the framework of density functional theory (DFT). Geometric optimization confirms that the material crystallizes in an orthorhombic structure with the C222<sub>1</sub> space group. The calculated structural parameters exhibit excellent agreement with available experimental data, showing a deviation of less than 2%. The thermodynamic and dynamic stability of the system is unequivocally confirmed by a negative formation energy (− 0.386&#xa0;eV/atom), a near-zero convex hull energy (<i>E</i><sub><i>hull</i></sub> = 0.002&#xa0;eV/atom), and phonon dispersion curves free of imaginary frequencies. Electronic structure analyses, refined using the HSE06 hybrid functional to overcome the limitations of standard GGA functionals, reveal that the compound possesses an indirect band gap of 3.684&#xa0;eV, characterizing it as a wide-bandgap material. Optical analyses indicate high transparency in the visible region, coupled with a strong photo response in the near and far ultraviolet (UV) regions. Notably, KH<sub>8</sub>N<sub>3</sub> significantly surpasses the US Department of Energy (DOE) 2025 targets, achieving a gravimetric capacity 8.97 wt% and a volumetric density 109.52&#xa0;g/L. Furthermore, the calculated desorption temperature of 301.53&#xa0;K indicates the potential for effective hydrogen release at room temperature. Mechanical analysis reveals that the structure is mechanically stable yet brittle (B/G = 1.66), while Mulliken population analysis confirms a mixed covalent-ionic bonding character. The findings demonstrate that the KH<sub>8</sub>N<sub>3</sub> hydride is a versatile and promising candidate for both next-generation solid-state hydrogen storage systems and UV-based optoelectronic applications.</p>

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Hydrogen storage potential and physical properties of KH8N3 hydride: a first-principles study

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Saadi Berri,
  • Çağatay Yamçıçıer

摘要

This study comprehensively investigates the structural, electronic, optical properties, as well as the hydrogen storage potential, of the KH8N3 hydride using first-principles calculations within the framework of density functional theory (DFT). Geometric optimization confirms that the material crystallizes in an orthorhombic structure with the C2221 space group. The calculated structural parameters exhibit excellent agreement with available experimental data, showing a deviation of less than 2%. The thermodynamic and dynamic stability of the system is unequivocally confirmed by a negative formation energy (− 0.386 eV/atom), a near-zero convex hull energy (Ehull = 0.002 eV/atom), and phonon dispersion curves free of imaginary frequencies. Electronic structure analyses, refined using the HSE06 hybrid functional to overcome the limitations of standard GGA functionals, reveal that the compound possesses an indirect band gap of 3.684 eV, characterizing it as a wide-bandgap material. Optical analyses indicate high transparency in the visible region, coupled with a strong photo response in the near and far ultraviolet (UV) regions. Notably, KH8N3 significantly surpasses the US Department of Energy (DOE) 2025 targets, achieving a gravimetric capacity 8.97 wt% and a volumetric density 109.52 g/L. Furthermore, the calculated desorption temperature of 301.53 K indicates the potential for effective hydrogen release at room temperature. Mechanical analysis reveals that the structure is mechanically stable yet brittle (B/G = 1.66), while Mulliken population analysis confirms a mixed covalent-ionic bonding character. The findings demonstrate that the KH8N3 hydride is a versatile and promising candidate for both next-generation solid-state hydrogen storage systems and UV-based optoelectronic applications.