Surface‐Charge‐Regulated Porous Water for Interfacial Phase‐Transition Control

Angstrom-confined water in porous scaffolds is sensitive to interfacial electrostatics, yet cross-material predictability is limited because pore geometry and surface chemistry change simultaneously. This work introduces Surface-Charge-Regulated Porous Water (SCR-PW) as a tunable functional microenvironment where framework charge serves as a deterministic parameter to modulate hydration under fixed topology. By utilizing MFI-type ZSM-5 zeolites (∼5.5 Å), a continuous gradient of negative framework charge is established by systematically narrowing the Si/Al ratio. This intensified interfacial electrostatic environment induces pronounced spatial layering and orientational polarization of interfacial water, producing a dynamically persistent, surface-organized hydration state distinct from bulk-like water. Such electrostatic constraint reshapes the phase-transition free-energy landscape, lowering the nucleation barrier by reducing the required structural rearrangement independent of geometric confinement. Experimental data confirm that SCR-PW facilitate gas-liquid mass transfer compared to bulk water. In representative phase transformations, SCR-PW accelerate transition kinetics by curtailing induction times and enhancing conversion, while maintaining invariant equilibrium features. In-situ neutron diffraction reveals that increased framework charge stabilizes the hydrogen-bonded host lattice by suppressing molecular thermal motion. This study provides an MFI-based proof of concept for regulating confined-water phase behavior through framework-charge engineering for creating intelligent porous aqueous microenvironments to regulate phase behavior and selective mass transport.