A customized zeolitic imidazolate framework enabling bionic preconcentration of ultralow CO2

Abstract

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 Å) and cyano groups (–CN), enabling highly selective adsorption of CO₂ (36.2 cm³ g⁻¹) over N₂ (1.6 cm³ g⁻¹) at 298 K. The mechanism involves unique –CN⋯CO₂⋯–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 N₂) 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%.