Isotopologue-induced structural dynamics of a triazolate metal-organic framework for efficient hydrogen isotope separation.

Zhang, Linda; Röß-Ohlenroth, Richard; Peterson, Vanessa K; Duyker, Samuel G; Li, Cheng; Fiorio, Jhonatan Luiz; Joswig, Jan-Ole; Dinnebier, Robert et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Efficient hydrogen isotope separation remains the biggest challenge due to the nearly identical physicochemical properties of H<sub>2</sub> and D<sub>2</sub>. Through in situ neutron powder diffraction and gas adsorption experiments, we investigate the hydrogen isotopologue-induced structural dynamics of the triazole-based metal-organic framework [Mn(ta)<sub>2</sub>]. Gas loading induces a measurable lattice expansion, more pronounced for H<sub>2</sub> than D<sub>2</sub>, and two distinct adsorption sites are identified with a subtle but significant difference in the occupancy of H<sub>2</sub> and D<sub>2</sub> at 60 K. Cryogenic thermal desorption spectroscopy after exposure to a 1:1 isotope mixture reveals an exceptionally high D<sub>2</sub>/H<sub>2</sub> selectivity of 32.5 at 60 K. When exposed to a D<sub>2</sub>/H<sub>2</sub> mixture of 5:95, D<sub>2</sub> enriches to 75% in a single cycle. Given the commercial availability of the ligand and the scalability of the dia-framework topology across divalent transition metals, upscaling for industrial-scale deuterium separation is a realistic prospect. Our results give crucial molecular-level insights into isotopologue-induced structural dynamics in triazolate-based MOFs and provide guidance for improvement of isotope separation materials.