What question did this study set out to answer?

To determine how different alkali cations (Li, Na, K) regulate hydrogen vacancy formation, thermodynamic stability, and dehydrogenation pathways in alkali–ammonium compounds.

August 16, 2026Canadian Journal of Chemistry

Cation-dependent hydrogen vacancy stability in XNH 4 (X = Li, Na, K): thermodynamic crossover, chemical potential, and implications for hydrogen release

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Authors

TST. SaadiUniversité de M'Sila ZCZ. CharifiUniversité de M'Sila TGT. GhellabUniversité de M'Sila

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Implication

First-principles study demonstrates cation-dependent hydrogen vacancy stability in alkali–ammonium compounds, highlighting thermodynamic principles for solid-state hydrogen storage.

Key Points

To determine how different alkali cations (Li, Na, K) regulate hydrogen vacancy formation, thermodynamic stability, and dehydrogenation pathways in alkali–ammonium compounds.
Performed first-principles density functional theory calculations using the generalized gradient approximation.
Calculated Gibbs free energy changes as a function of hydrogen chemical potential at room temperature, including zero-point energy and entropic corrections.
Evaluated pressure–temperature transition mappings and electronic band structures across single- and double-hydrogen vacancy states.
LiNH4 consistently favored full double-hydrogen (2H) removal across the entire chemical potential range without phase crossover.
NaNH4 and KNH4 exhibited thermodynamic crossovers between 1H and 2H vacancy states, with the KNH4 transition occurring at an experimentally reachable 1.8 × 10^-7 atm at 300 K.
Hydrogen release induced an electronic transition from a metallic state to p-type semiconductors, opening band gaps of 1.37 eV in LiNH2, 0.80 eV in NaNH2, and 0.93 eV in KNH2.

Cite This Study

Saadi et al. (2026) studied this question.

synapsesocial.com/papers/6a817a11f2fb91fc834ad981 https://doi.org/10.1139/cjc-2026-0060

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Implication

First-principles study demonstrates cation-dependent hydrogen vacancy stability in alkali–ammonium compounds, highlighting thermodynamic principles for solid-state hydrogen storage.

Cation-dependent hydrogen vacancy stability in XNH 4 (X = Li, Na, K): thermodynamic crossover, chemical potential, and implications for hydrogen release

Discussion

Member takes

Implication

Key Points

Cite This Study

Cation-dependent hydrogen vacancy stability in XNH 4 (X = Li, Na, K): thermodynamic crossover, chemical potential, and implications for hydrogen release

Discussion

Member takes

Implication

Key Points

Cite This Study

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