Efficient CO2 capture by ZIF-8-derived in-situ nitrogen-doped nanoporous carbon with ultra-high selectivity and stability

Abstract

Global warming and the increasing frequency of extreme weather caused by the gradual increase in CO2 concentration in the atmosphere are urgent issues that must be addressed. In this study, ZIF-8-derived in-situ nitrogen-doped porous carbon materials were prepared through one-step pyrolysis of ZIF-8. The synthesis was gradually optimized by exploring different pyrolysis temperatures to determine the optimal ZIF-8-derived porous carbon for CO2 adsorption. The CO2-adsorption capacity of ZIF-8–800 reached 5.22 and 6.19 mmol g−1 at 25 ℃ and 0 ℃ (1 bar), respectively. After five cycles, its CO2-adsorption capacity decreased by only about 1.7 %. Moreover, the CO2/N2 selectivity at 1 bar was as high as 21.2 (48.9 at 0.05 bar), and the isothermal adsorption heat was also within a moderate range (31 kJ mol−1). The superior CO2 adsorption performance was found to originate from the comprehensive effect of the three-dimensional pore structure that combined reasonably coordinated micropores, mesopores, and macropores, as well as some specific favorable N/O groups. The results indicate the broad application prospects of ZIF-8-Ts in CO2 capture and separation and provide new ideas for the sustainable application of novel MOF-derived porous carbon materials.