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

ABSTRACT 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.