Electrostatic modulation on Ni-gallate enables control over gate-opening transitions for low-pressure CO2 capture

Heterometallic Ni/In-gallate was constructed by In 3+ incorporation. • CO 2 gate-opening pressure shifted from 0.10 to 0.07 bar at 298 K. • CO 2 /N 2 selectivity of Ni/In-gallate increased by about 8.5 times. • CO 2 uptake of Ni/In-gallate increased by 91.8% at 0.15 bar. • Ni/In-gallate retained 96.7% (82.15%) CO 2 breakthrough time at 40% (80%) RH. Flexible metal–organic frameworks (MOFs) exhibiting gate-opening transitions are promising for gas separations, yet their performance at low partial pressures is fundamentally constrained by the intrinsic energy barrier governing the structural transition. In this work, In 3+ was incorporated into the Ni-gallate framework to construct heterometallic Ni-O···In motifs. This modification induced localized charge redistribution and enhanced the electrostatic potential gradient within the pore environment. As a result, the gate-opening pressure for CO 2 is shifted from 0.10 to 0.07 bar, accompanied with a significant uptake at 0.15 bar (from 1.83 to 3.51 mmol g −1 ) and IAST selectivity (13287). In situ DRIFTS and kinetic analyses further show a faster establishment of CO 2 adsorption features and a stronger interaction between EPM-Ni/In-gallate and CO 2 . Changes in the electrostatic potential in localized regions within the EPM-Ni/In-gallate were investigated using XAS and PALS measurements. Furthermore, DFT calculations show a substantial reduction in the free-energy barrier for CO 2 migration between adjacent cavities. These results are consistent with a contribution from modified pore-wall polarization and gating energetics. This work identifies electrostatic control as a promising approach for tuning gate-opening transitions in flexible porous materials, providing new design principles for low-pressure gas capture.