Strain-induced geometric modulation of nanopores for enhanced hydrogen isotopologue separation <i>via</i> quantum sieving

The exploitation of quantum effects in light isotopologue separation represents a pioneering advancement in isotopic purification technologies. This study employs first-principles calculations to explore the mechanisms underlying the separation of hydrogen isotopologues facilitated by strain-engineered nanopores, emphasizing that the geometry of these nanopores critically governs separation efficiency through the intricate interplay between quantum tunneling and zero-point energy (ZPE) effects. We demonstrate that the application of directional strain to carbon nitride membranes, specifically N-graphyne (<i>r</i>-N-GY) and N-graphdiyne (<i>r</i>-N-GDY), results in distinct nanopore geometries with profound separation efficiency. The strained <i>r</i>-N-GY membrane with quasi-circular nanopores achieves industry-grade performance across a wide strain range (14-18%) along the armchair (AC) direction, effectively separating multiple hydrogen isotopologue pairs (D₂/H₂, DT/H₂, T₂/HD, <i>etc.</i>). In contrast, the strained <i>r</i>-N-GDY membrane with slit-like nanopores exhibits limited utility, selectively sieving isotopologue pairs only under a specific strain condition of 3.5% applied along the zig-zag direction. This discrepancy arises from the strain-induced geometric transformations that AC-strained <i>r</i>-N-GY develops quasi-circular nanopores that amplify ZPE effects, thereby enhancing isotopologue selectivity. These insights establish geometric modulations as a critical design principle for quantum sieving materials and advance the frontier of strain-engineered membranes for isotopic separation. This work provides both theoretical insights into the quantum-driven separation mechanism and practical guidelines for developing high-performance isotopic purification systems.