Understanding the Influence of N-Doping on the CO₂ Adsorption Characteristics in Carbon Nanomaterials

Abstract

Compared to metal–organic frameworks and zeolites, carbon-based materials are particularly interesting for gas capture applications due to their better stability against moisture and corrosive flue gases. Increasing the accessible surface area and incorporation of heteroatoms are generally the two different strategies put forward to further enhance the adsorption characteristics of carbon materials. The influence of nitrogen incorporation on the gas adsorption characteristics, especially CO2 adsorption, is however a controversial research topic with conflicting conclusions reported by various studies. In the present work, using vertically aligned carbon nanotubes (VACNTs), we investigate for the first time the influence of N-doping on the CO2 adsorption characteristics of carbon materials. The present study aims to shed additional light on the parameters known so far as well as those that are currently not considered but are additionally responsible for gas adsorption in functionalized carbon materials. To this end vertically aligned carbon nanotubes (VACNTs) are ideal carbon model structures for gas adsorption studies as they have a well-defined, reproducible mesoporous pore structure with a chemically homogeneous surface. Thus, the interfering influence of micropores, which are generally present in carbon-based adsorbents, is avoided, making a straightforward interpretation of the exact influence of N-doping possible for the first time. N-incorporation in the form of pyridinic or pyrrolic/pyridonic groups is achieved by using a N2 rf plasma treatment. The presence of these nitrogen functionalities is found to have a beneficial influence on the CO2 adsorption characteristics over a wide range of pressure (0–36 bar). The nature of interaction is determined by calculating the isosteric heat of adsorption and finally by comparing the adsorption characteristics of as-prepared and N-doped VACNTs with oxygen functionalized VACNTs; the importance of determining the oxygen functional groups in the adsorbent is presented.

Macroalgae-derived nitrogen-doped hierarchical porous carbons with high performance for H2 storage and supercapacitors

“…Although the existing O, N groups may have some detrimental effects for H 2 storage, 1,3 they are well-known to enhance hydrophilicity and defective sites, beneting for CO 2 capture and charge storage with introduction of extra pseudocapacitance. 7,14 Multiple C chemical states on the surface of carbons were conrmed by high resolution of C1s peak (Fig. 3b), which can be deconvoluted into peaks at around 284.5, 285.1 and 287.4 eV, corresponding to C-C/C]C, C-O/C] N and C]O/C-N, respectively.…”

“…Of late, there are increasing evidence to suggest that carbons with high surface areas are highly effective in gas storage application. [6][7][8] It is thought that carbons with tuned pores might be used to solve climate change especially in relation to high-density H 2 storage. Moreover, the fabrication of devices with highly-efficient energy storage has great importance in solving issue of energy crisis.…”

An Enhanced Carbon Capture and Storage Process (e-CCS) Applied to Shallow Reservoirs Using Nanofluids Based on Nitrogen-Rich Carbon Nanospheres

“…[16,37,38,39], but not widely at the nanoscale level, with spherical structures allowing their application in geological deposits. Many carbon nanostructures have been evaluated for CO 2 capture, among them nanofibers, nanosheets, and nanotubes, leading to adsorption capacities ranging from 0.26 to 4.15 mmol g −1 under atmospheric conditions [16,40,41,42,43,44,45]. However, these materials are not applicable to reservoirs due to their structure and dimensions that might affect the nature of the reservoir’s porous structure.…”

Carbon‐based adsorbents for post‐combustion capture: a review

“…Tuning the surface chemistry of carbons represents another way to improve CO 2 adsorption. One simple approach to do so is to involve hetero‐atoms into the carbon matrix, which led to enhancement of surface affinity towards the CO 2 molecule …”

“…One simple approach to do so is to involve hetero-atoms into the carbon matrix, which led to enhancement of surface affinity towards the CO 2 molecule. [192][193][194][195][196][197] Nitrogen has been the most widely used element to modify carbons. This can be achieved by simply treating carbons in NH 3 gas at high temperatures.…”