Air-oxidation of phenolic resin aerogels: backbone reorganization, formation of ring-fused pyrylium cations, and the effect on microporous carbons with enhanced surface areas

Abstract

Air-oxidation at 240 °C, followed by pyrolytic carbonization, revealed that carbons from phenolic resins contain fused pyrylium rings and phenoxides.

Polyacrylonitrile‐Derived Sponge‐Like Micro/Macroporous Carbon for Selective CO2 Separation

“…The pre-oxidation process makes the PANb eing stably coated on the GO sheetsb yp artial cross-linking and cyclization reactions of PANs ide chains. [10] The introductiono fG Oe nhances the molecular orientation of the precursor polymer PANd uring pre-oxidization and pyrolysisp rocesses by limiting the disorientation of chain segmentst hrough p-p interaction. If PAN/GO polymer (Figure S1 a) was directly subjected to activation, skippingo ver pre-oxidation and pyrolysis steps, or if the oxidized PAN/GO composite ( Figure S1 b) was directly subjected to activation, skippingo ver the pyrolysis step, the obtained samples PG-K and PGO-K could not form the sponge-like macroporous morphology( Figure S1 c, d).…”

“…The presentr esults agree with those in the literature, which show that without pre-oxidation, the yield of carbon is much less and pre-oxidation increases the surface areas of the carbon structure. [10] The introductiono fG Oe nhances the molecular orientation of the precursor polymer PANd uring pre-oxidization and pyrolysisp rocesses by limiting the disorientation of chain segmentst hrough p-p interaction. [11] In contrast, the carbon sample prepared in the absence of GO (denoted as PC, Figure S1 ei nt he Supporting Information) is compacted together, indicating the key role of GO in the formation of the spongelike macroporous structure.…”

“We Are Here!” Oxygen Functional Groups in Carbons for Electrochemical Applications

“…For instance, in 2017, Far and co-workers published a comprehensive study on the chemical transformations during pyrolytic conversion of phenolic resins to carbons. 37 In their study, they analyzed the evolution of the chemical structure and functional groups of phenol–formaldehyde, resorcinol–formaldehyde, and phloroglucinol–formaldehyde resins, as well as a phloroglucinol–terephthalaldehyde upon heat treatment. The samples were gelled using an HCl-catalyzed synthesis and dried in supercritical CO 2 yielding monolithic aerogels.…”

“…On the edges, there are pyrilium functional groups. Reproduced from ref ( 37 ) with permission from the Royal Society of Chemistry. (b) Scheme of aromatization and cross-linking of polyketo chains and optical microscopy picture of acetic anhydride derived carbonaceous products obtained by hydrothermal condensation at 250 °C.…”

Structure Manipulation of Carbon Aerogels by Managing Solution Concentration of Precursor and Its Application for CO2 Capture

“…Carbon aerogels synthesized by using precursors of resorcinol and formaldehyde have been received much attention [22,23]. This paper demonstrates that the structure of carbon aerogel can be managed by solution concentration of its precursors, thus improving its CO 2 adsorption performance.…”