Hierarchical porous nitrogen-doped carbon beads derived from biosourced chitosan polymer

Abstract

Carbon microbeads with diameters of a few hundreds of microns are produced by dropping chitosan acetate (CA) solution in liquid nitrogen, freeze drying and thermal treatment in inert atmosphere at 700°C. The structure of the beads is characterized by hierarchical porosity at the three length scales: (i) macropores originating from the phase separation during the water ice crystal grow inside the droplets, immersed in liquid nitrogen, (ii) arising in course of the beads thermal treatment, leading to the removal of the porogen molecules (Pluronic F127) added to the CA solution and (iii) micropores induced by the carbonization of chitosan resin. The carbon beads have a rigid skin which present wrinkles with well-defined structure. The carbon bead pore size and volume could be tuned by varying the type and amount of cross-linkers (glyoxal and glyoxylic acid) and template. This was related to the chitosan ability to cross-link in a different manner with the cross-linkers as showed by 13 C NMR resulting in chitosan resin able to self-assemble with Pluronic F-127 template through Hbonding interactions.The beads are produced by a green process employing entirely biosourced and renewable materials that make them attractive for the large scale applications requiring nanoporous carbons.

Sodium Storage in Coal/Biomass‐Derived Carbon/Carbon 3D Networks

“…The high‐resolution C 1s spectra can be deconvoluted into three peaks and shown in Figure a–b. For CGCs and CGC‐CS 7, the three peaks at 284.6, 285.0 and 286.1 eV were assigned to C=C/C−C, C−N and C−O stretching vibration, respectively . The high‐resolution N1s spectra were deconvoluted and shown in Figure c–d, CGC‐CS 7 has higher N content compared to pure CGCs, suggesting that most of N element come from chitosan.…”

“…The high‐resolution N1s spectra were deconvoluted and shown in Figure c–d, CGC‐CS 7 has higher N content compared to pure CGCs, suggesting that most of N element come from chitosan. Three peaks at 398.5, 400.5 and 403.0 eV were observed, corresponding to pyridine N, pyrrole N and pyridine oxide . Obviously, the relative content of N functional groups for CGC‐CS 7 were higher than CGCs, indicating that chitosan can introduce the N functional groups.…”

“…Three peaks at 398.5, 400.5 and 403.0 eV were observed, corresponding to pyridine N, pyrrole N and pyridine oxide. [32] Obviously, the relative content of N functional groups for CGC-CS 7 were higher than CGCs, indicating that chitosan can introduce the N functional groups. And some studies have shown that introducing N element in carbon skeleton not only can improve the conductivity, but also enhance the Faraday reaction.…”

“…For CGCs and CGC-CS 7, the three peaks at 284.6, 285.0 and 286.1 eV were assigned to C=C/CÀ C, CÀ N and CÀ O stretching vibration, respectively. [31][32][33] The high-resolution N1s spectra were deconvoluted and shown in Figure 2c-d, CGC-CS 7 has higher N content compared to pure CGCs, suggesting that most of N element come from chitosan. Three peaks at 398.5, 400.5 and 403.0 eV were observed, corresponding to pyridine N, pyrrole N and pyridine oxide.…”

Eco-Friendly Synthesis of Nitrogen-Doped Mesoporous Carbon for Supercapacitor Application

“…Phloroglucinol/glyoxylic acid resin was cross-linked with triethylenediamine (TEDA) as nitrogen source in water at room temperature and in the absence of a template, resulting in the formation of microporous carbon spheres [33]. Chitosan, a biocompatible and green precursor was as well proposed as a simultaneous carbon and nitrogen precursor which was able to assemble with Pluronic F-127 template to obtain N-doped carbon beads with hierarchical porosity by a soft-template assisted by a freezing-drying technique [34].…”