Decoding Carbon-Based Materials' Properties for High CO2 Capture and Selectivity.

Abstract

Carbon-based materials are well established as low-cost, easily synthesizable, and low regeneration energy adsorbents against harmful greenhouse gases such as CO2. However, the development of such materials with exceptional CO2 uptake capacity needs well-described research, wherein various factors influencing CO2 adsorption need to be investigated. Therefore, five cost-effective carbon-based materials that have similar textural properties, functional groups, and porous characteristics were selected. Among these materials, biordered ultramicroporous graphitic carbon had shown an excellent CO2 capture capacity of 7.81 mmol/g at 273 K /1 bar with an excellent CO2 vs N2 selectivity of 15 owing to its ultramicroporous nature and unique biordered graphitic morphology. On the other hand, reduced graphene revealed a remarkable CO2 vs N2 selectivity of 57 with a CO2 uptake of 2.36 mmol/g at 273 K/1 bar. In order to understand the high CO2 capture capacity, important properties derived from adsorption/desorption, Raman spectroscopy, and X-ray photoelectron spectroscopy were correlated with CO2 adsorption. This study revealed that an increase in ultramicropore volume and sp2 carbon (graphitic) content of nanomaterials could enhance CO2 capture significantly. FTIR studies revealed the importance of oxygen functionalities in improving CO2 vs N2 selectivity in reduced graphene due to higher quadruple–dipole interactions between CO2 and oxygen functionalization of the material. Apart from high CO2 adsorption capacity, biordered ultramicroporous graphitic carbon also offered low regeneration energy and excellent pressure swing regeneration ability for five consecutive cycles.