High‐Performance CO<sub>2</sub> Capture from Air by Harnessing the Power of CaO‐ and Superbase‐Ionic‐Liquid‐Engineered Sorbents
Debabrata Moitra, Narges Mokhtarinori, Kevin M. Siniard, Liqi Qiu, Juntian Fan, Zhun Dong, Wenda Hu, Hongjun Liu, De‐en Jiang, Hongfei Lin, Jian Zhi Hu, Meijia Li, Zhenzhen Yang, Sheng Dai
Abstract
Abstract Direct air capture (DAC) of CO 2 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 CO 2 interaction with superbase‐derived ionic liquids (SILs), high‐performance and tunable sorbents in DAC of CO 2 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 CO 2 uptake capacity via volumetric (at 0.4 mbar) and breakthrough test (400 ppm CO 2 source), rapid interaction kinetics, facile CO 2 releasing, and stable sorption/desorption cycles. Operando diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS) analysis under simulated air atmosphere and solid‐state NMR under 13 CO 2 atmosphere demonstrated the critical roles of the SIL species in low‐concentration CO 2 capture. The fundamental insights obtained in this work provide guidance on the development of high‐performance sorbents in DAC of CO 2 by leveraging the combined advantages of porous solid scaffolds and the unique features of CO 2 ‐philic ionic liquids.