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Using an advanced cryogenic thermal desorption spectroscopy (ACTDS) apparatus together with the temperature-programmed desorption (TPD) methodology, three MOF materials with different textural characteristics were examined for the separation of an equimolar H2/D2 mixture through quantum sieving. Finally, a universal fundamental correlation between the separation performance of (equilibrium) quantum sieving and pore size with temperature is established, which, for specific pore apertures, results in a subordinate local optimal operational temperature (LOOT) phenomenon that is dominant at local temperatures; the influence of the textural characteristics of different materials on this correlation is also illustrated in detail and clearly demonstrates that a good material for efficient H2/D2 quantum sieving should possess homogeneous hydrophilic pores with only one strong adsorption site. These results will exert great directive significance on defining the optimal operational conditions and suitable materials for more effective H2/D2 quantum sieving performance in a practical way. [ABSTRACT FROM AUTHOR]

An ultramicroporous MOF material, {[Fe(OH)(H2bta)](H2O)}n, was diligently selected for the experimental investigations of ultralow-temperature separation of H2/D2 through quantum sieving. With an extreme two-dimensional confinement experienced by hydrogen molecules, an extraordinary separation factor as high as 41.4 ± 0.4 at 20 K was for the first time obtained from experiment. [ABSTRACT FROM AUTHOR]

We investigated the effect of Pd and Ni dopants on the formation and desorption of tritiated water (T 2 O) molecules from the Li 2 TiO 3 (001) surface using first-principles calculations coupled with the climbing-image nudged elastic band method. We calculated the energy barriers for T 2 O production and desorption on the pure Li 2 TiO 3 surface to be 0.94 and 0.64 eV, respectively. The Pd and Ni dopants enhanced T 2 O formation by reducing the formation energy of O vacancies, and T 2 O generated spontaneously on the dopant surface. Moreover, we found that dopant atoms affect the charge transfer of neighboring atoms, which leads to orbital hybridization and the generation of a chemical bond between the O and T on the doped Li 2 TiO 3 surface. In addition, desorption of T 2 O from the doped Li 2 TiO 3 surface requires a relatively low energy (<0.50 eV). This theoretical study suggests that doping the Li 2 TiO 3 surface with metal atoms is an effective strategy for producing T 2 O molecules and is beneficial to T release., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)