Strontium cations guarding chabazite zeolite windows for selective deuterium recovery

Deuterium is indispensable for nuclear fusion and isotopic labeling; however, the separation of high‐purity deuterium from hydrogen isotope mixtures (D 2 /H 2 ) remains challenging due to their nearly identical physicochemical properties. Herein, we report a strontium‐cation‐guarded chabazite (CHA) zeolite that exhibits a combined effect of favorable diffusion kinetics and tailored equilibrium adsorption for the quantum sieving of D 2 /H 2 . Strontium cations positioned at 8‐membered ring windows facilitate preferential D 2 diffusion and enrichment during adsorption, while simultaneously enabling rapid H 2 release during desorption. This decoupling of adsorption–desorption dynamics results in exceptional D 2 /H 2 performance. At 40 K, the optimal adsorbent achieves a dynamic D 2 /H 2 selectivity of 3.10 and a D 2 capacity of 6.60 mmol g −1 . Breakthrough tests followed by a two‐stage desorption process (direct purging and subsequent heating) yielded D 2 recoveries of 52.7% and 47.3%, with corresponding purities of 73.3% and 98.9%, respectively.