Controlling pore size and pore functionality in sp2-conjugated microporous materials by precursor chemistry and salt templating. Issue 41 (14th October 2020)

• Record Type: Journal Article
• Authors: Youk, Sol; Hofmann, Jan P.; Badamdorj, Bolortuya; Völkel, Antje; Antonietti, Markus; Oschatz, Martin
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 41(2020)
• Page Start: 21680
• Page End: 21689
• Publication Date: 2020-10-14
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0ta05856d
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Condensation of melamine and citrazinic acid leads to highly functionalized carbon materials for selective carbon dioxide adsorption. Abstract : The synthesis of sp 2 -conjugated, heteroatom-rich, "carbonaceous" materials from economically feasible raw materials and salt templates is reported. Low cost citrazinic acid (2, 6-dihydroxy-4-pyridinecarboxylic acid) and melamine are used as components to form a microporous, amorphous framework, where edges of the covalent frameworks are tightly terminated with nitrogen and oxygen moieties. ZnCl2 as the porogen stabilizes structural microporosity as well as nitrogen and oxygen heteroatoms up to comparably high condensation temperatures of 750 and 950 °C. The specific surface area up to 1265 m 2 g −1 is mainly caused by micropores and typical of heteroatom-rich carbon materials with such structural porosity. The unusually high heteroatom content reveals that the edges and pores of the covalent structures are tightly lined with heteroatoms, while C–C or C–H bonds are expected to have a minor contribution as compared to typical carbon materials without or with minor content of heteroatoms. Adsorption of water vapor and carbon dioxide are exemplarily chosen to illustrate the impact of this heteroatom functionalization under salt-templating conditions on the adsorption properties of the materials. 27.10 mmol g −1 of H2 O uptake (at p / p 0 = 0.9) can be achieved, which also proves the very hydrophilic character of the pore walls, while the maximum CO2 uptake (at 273 K) is 5.3 mmol g −1 . At the same time the CO2 /N2 adsorption selectivity at 273 K can reach values of up to 60. All these values are beyond those of ordinary high surface area carbons, also differ from those of N-doped carbons, and are much closer to those of organized framework species, such as C2 N.