A customized zeolitic imidazolate framework enabling bionic preconcentration of ultralow CO2

Advancing our understanding of global climate, particularly in polar regions, requires accurate detection of carbon dioxide (CO2) in ice cores and deep sea environments. However, detecting trace levels of CO2 in these areas presents significant challenges. We introduce a novel preconcentration approach using functionalized zeolitic imidazolate framework, ZIF-8(CN), for the detection of ultra-low CO2. ZIF-8(CN) has small pores (4.4 angstrom) and cyano groups (-CN), enabling highly selective adsorption of CO2 (36.2 cm(3) g(-1)) over N-2 (1.6 cm(3) g(-1)) at 298 K. The mechanism involves unique -CN center dot center dot center dot CO2 center dot center dot center dot-CN interactions within the pore structure. When cast into a film on an aluminum substrate, ZIF-8(CN) demonstrates exceptional CO2 preconcentration capability (1 ppm in N-2) with an extraordinary preconcentration factor of 748, outperforming traditional ZIF and zeolite materials. Additionally, a ZIF-8(CN) preconcentrator is designed and fabricated with bionic gas flow of fractal structure which optimizes the gas-film contact, and thus its performance is further improved by 115%.