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 CO 2 . However, the development of such materials with exceptional CO 2 uptake capacity needs well-described research, wherein various factors influencing CO 2 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 2 capture capacity of 7.81 mmol/g at 273 K /1 bar with an excellent CO 2 vs N 2 selectivity of 15 owing to its ultramicroporous nature and unique biordered graphitic morphology. On the other hand, reduced graphene revealed a remarkable CO 2 vs N 2 selectivity of 57 with a CO 2 uptake of 2.36 mmol/g at 273 K/1 bar. In order to understand the high CO 2 capture capacity, important properties derived from adsorption/desorption, Raman spectroscopy, and X-ray photoelectron spectroscopy were correlated with CO 2 adsorption. This study revealed that an increase in ultramicropore volume and sp 2 carbon (graphitic) content of nanomaterials could enhance CO 2 capture significantly. FTIR studies revealed the importance of oxygen functionalities in improving CO 2 vs N 2 selectivity in reduced graphene due to higher quadruple–dipole interactions between CO 2 and oxygen functionalization of the material. Apart from high CO 2 adsorption capacity, biordered ultramicroporous graphitic carbon also offered low regeneration energy and excellent pressure swing regeneration ability for five consecutive cycles.

Pore Size-Regulated Vertically Aligned CoFe-LDH on a Carbon Support for the Oxygen Evolution Reaction

“…37,38 In contrast, BUGC had a graphitic layered structure with a high concentration of sp 2 carbon, which is electron-rich in nature. 36 These electron-rich conjugated double bonds of BUGC presumably led to long-range π−π interactions with the metal cations, which hindered the vertical growth of LDH on the carbon surface, resulting in a mostly parallel growth of LDH on the surface of BUGC (Scheme 2).…”

“…The C 1s XPS spectrum was deconvoluted into five subpeaks (Figures d and S8d, S9d, SI). CoFe-LDH/MMC, CoFe-LDH/BUGC, and CoFe-LDH/IMC had five types of functionalizations situated at 284.6 (CC, sp 2 carbon), 285.1 (C–C/C–H, sp 3 carbon), 286.2 (C–O, alcohol functionalities), 287.5 (CO, ketonic functionalities), and 288.9 eV (O–CO, carboxylic functionalities) (Figures d and S8d, S9d, SI) …”

“…35 The concentration of cobalt was higher in CoFe-LDH/MMC (45.51%), followed by CoFe-LDH/IMC (41.99%) and CoFe-LDH/BUGC (41.02%) (Table S2 3d and S8d, S9d, SI). 36 In Situ Crystallization Mechanism of LDH Formation. LDH was grown by utilizing porous carbon as a support material.…”

“…Presumably, the vertical growth of LDH on MMC and IMC surfaces was due to the short-range electrostatic interactions between OFGs and the metal cations, followed by layer-by-layer growth (Scheme ). The driving force for the vertical growth could be due to van der Waals forces between LDH layers. , In contrast, BUGC had a graphitic layered structure with a high concentration of sp 2 carbon, which is electron-rich in nature . These electron-rich conjugated double bonds of BUGC presumably led to long-range π–π interactions with the metal cations, which hindered the vertical growth of LDH on the carbon surface, resulting in a mostly parallel growth of LDH on the surface of BUGC (Scheme ).…”

Graphene-Based Composite for Carbon Capture

“…To cater demands of large-scale industrial applications, chemical costs and energy consumption must be minimized to the fullest extent possible . Various adsorbent materials that have been developed recently are zeolite, metal oxides, porous polymers, metal–organic frameworks (MOFs), porous silica, and carbon materials …”