Zinc metal-organic framework as a durable sorbent for deep capture of SO₂ and NH₃ in humid air

The efficient capture of ambient SO₂ and NH₃ is essential to protect human health and the environment. However, the respectively acidic and basic nature of the two hazards along with their low-level presence, significantly challenges the current adsorbents. Metal-organic frameworks (MOFs) featuring open metal sites offer the advantage of strong affinity to both SO₂ and NH₃, but their practical implementation is largely hampered by the performance diminishment and structure collapse in humid air. Here we report the non-covalent adsorption of acidic SO₂ and basic NH₃ on a single Zn MOF platform (FJI-H29) as well as its enhanced capture performance for low-pressure SO₂ and NH₃ in humid air. Guaranteed by the comparable-diameter channel and rich pore-decorations including uncoordinated O and N atoms, the framework exhibits superior overall uptake performance for low-pressure (< 0.5 kPa) SO₂ and NH₃ compared to the reported state-of-the-art amphoteric MOF sorbents, and achieves an extraordinarily high dense packing of the two dissimilar gases at 100 kPa. Moreover, FJI-H29 shows remarkable delays in breakthrough, corresponding to a 130% and 90% increased uptake for SO₂ and NH₃ in the presence of humidity. This work may pave the way for the development of acid-base amphoteric MOF sorbents under humid conditions.