Superhigh and reversible NH3 uptake of cobaltous thiocyanate functionalized porous poly ionic liquids through competitive and cooperative interactions

In this work, porous PIL-TAs were reported for superhigh capacity and reversible NH 3 uptake, where PIL-TAs are cobaltous thiocyanate (Co(II)(SCN) 4 2- , TA) functionalized poly ionic liquids (PILs). Due to the structural support of TA as well as the interactions between TA and imidazolium cation, the PIL-TAs possess porous structure and optimized properties. Superhigh NH 3 uptake capacity of 13.2–20.1 mmol g −1 at STP of PIL-TAs was achieved, which is higher than most of the reported sorbents. In detail, the cooperative interactions including the NH 3 coordinating with Co(II) instead of SCN - and hydrogen bonding of C2H in imidazolium (C2H…NH 3 ) benefit to high capacity of NH 3 uptake. Reversely, the NH 3 release would be directed by the competition of the free SCN - with NH 3 to reform PIL-TAs. The competitive interaction with SCN - promotes NH 3 release by temperature and pressure swinging, which contributes the adsorbents recyclable. The cooperative and competitive interactions make these PIL-TAs possess high gas capacity and feasible desorption, which might be a potential strategy for designing novel gas sorbents.