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

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