Synergistic effect of paired Cu(II) open metal sites for enhanced high-temperature hydrogen isotope separation
- Fenglei Wang
- Zhihai Fu
- Xingwen Feng
- Xiangyang Liu
- Zining Wang
- Chaofan Jiang
- Wenting Liu
- Yuchen Jiang
- Yu Luo
- Huimin Li
- Qingyang Wang
- Yuanhua Wang
- Song Qin
- Yongdong Jin
- Chuanqin Xia
- Lijian Ma
2026-08-10
The selective separation of hydrogen isotopes under mild cryogenic conditions remains a formidable challenge due to their nearly identical physicochemical properties. Here, we report a dual strategy of pore topology design and paired Cu(II) open metal sites (OMS) synergistic engineering to amplify chemical affinity quantum sieving (CAQS). Among three tailored Cu(II)-MOFs, Cu-ATC exhibited exceptional performance, achieving a D 2 /H 2 selectivity of 20 at 50 K (10 mbar) and 1.8 in breakthrough experiments at 77 K, demonstrating excellent H 2 /D 2 separation performance. The ultramicroporous topology of Cu-ATC fixes a Cu···Cu distance of 5.98 Å within one-dimensional channels, while Jahn–Teller distortion induces axial elongation at each Cu(II) center, thereby enhancing the accessibility of the d z 2 orbitals for interaction with hydrogen isotope molecules. This structural combination creates two closely spaced OMSs that enhance differential interactions with H 2 and D 2 , thereby driving isotope separation via CAQS. The distinct binding strength is evidenced by in situ DRIFTS (v(H-H)/ v(D-D) red-shift of 203 cm −1 / 147 cm −1 ) and by DFT calculations showing stronger adsorption of H 2 ( − 9.7 kJ mol −1 ) and D 2 ( − 13.0 kJ mol −1 ). These microscopic differences account for the observed D 2 /H 2 selectivity, highlighting the potential of paired OMSs engineering for CAQS-based isotope separation under mild cryogenic conditions.