New Class of Type III Porous Liquids: A Promising Platform for Rational Adjustment of Gas Sorption Behavior

Abstract

Porous materials have already manifested their unique properties in a number of fields. Generally, all porous materials are in a solid state other than liquid, in which molecules are closely packed without porosity. "Porous" and "liquid" seem like antonyms. Herein, we report a new class of Type 3 porous liquids based on rational coupling of microporous framework nanoparticles as porous hosts with a bulky ionic liquid as the fluid media. Positron annihilation lifetime spectroscopy (PALS) and CO₂ adsorption measurements confirm the successful engineering of permanent porosity into these liquids. Compared to common porous solid materials, as-synthesized porous liquids exhibited pronounced hysteresis loops in the CO₂ sorption isotherms even at ambient conditions (298 K, 1 bar). The unique features of these novel porous liquids could bring new opportunities in many fields including gas separation and storage, air separation and regeneration, gas transport, and permanent gas storage at ambient conditions.

Keywords: gas sorption; hysteretic desorption; ionic liquid; porous frameworks; porous liquids.