Morphologically and compositionally tuned lithium silicate nanorods as high-performance carbon dioxide sorbentsElectronic supplementary information (ESI) available: Experimental and supplementary figures and tables included. See DOI: 10.1039/c6ta06133h

The effective capturing of carbon dioxide using regenerable high capacity sorbents is a prerequisite for industrial applications aiming at CO 2 capture and sequestration. The removal of CO 2 directly from chemical reaction environments at high temperature is a less energy intensive method of its separation with the added benefit of improved efficiency in equilibrium limited reactions. However, the separation of CO 2 at the typical reaction temperatures of 573-1073 K is a challenging task due to the non-availability of absorbents with kinetics comparable to reaction rates. Moreover their poor durability due to sintering and particle growth on prolonged use at high temperature is also an impediment to their practical application. Herein, we demonstrate the development of an efficient CO 2 absorbent material, made of Li 4 SiO 4 nanorods, with ultrafast sorption kinetics as well as remarkable durability. These nanorods enabled easier surface reaction with CO 2 due to shorter diffusion pathways for lithium from the bulk to the surface of the rods permitting extremely fast absorption of CO 2 . Furthermore, the compositional tuning of the materials helped to realize absorbents with extraordinary CO 2 absorption rates of 0.72 wt% s −1 at 100% CO 2 /923 K. The exceptional performance of these absorbents at lower temperatures (573-823 K) as well as lower CO 2 pressures (0.15 atm) demonstrates their potential in practical CO 2 separation applications. The lithium silicate nanorods derived by a microwave sol gel process display extremely fast CO 2 absorption rates as well as remarkable durability for prolonged application.