High‐Performance CO2 Capture from Air by Harnessing the Power of CaO‐ and Superbase‐Ionic‐Liquid‐Engineered Sorbents

Abstract

AbstractDirect air capture (DAC) of CO2 by solid porous materials represents an attractive “negative emission” technology. However, state‐of‐the‐art sorbents based on supported amines still suffer from unsolved high energy consumption and stability issues. Herein, taking clues from the CO2 interaction with superbase‐derived ionic liquids (SILs), high‐performance and tunable sorbents in DAC of CO2 was developed by harnessing the power of CaO‐ and SIL‐engineered sorbents. Deploying mesoporous silica as the substrate, a thin CaO layer was first introduced to consume the surface‐OH groups, and then active sites with different basicities (e. g., triazolate and imidazolate) were introduced as a uniformly distributed thin layer. The as‐obtained sorbents displayed high CO2 uptake capacity via volumetric (at 0.4 mbar) and breakthrough test (400 ppm CO2 source), rapid interaction kinetics, facile CO2 releasing, and stable sorption/desorption cycles. Operando diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS) analysis under simulated air atmosphere and solid‐state NMR under 13CO2 atmosphere demonstrated the critical roles of the SIL species in low‐concentration CO2 capture. The fundamental insights obtained in this work provide guidance on the development of high‐performance sorbents in DAC of CO2 by leveraging the combined advantages of porous solid scaffolds and the unique features of CO2‐philic ionic liquids.