Hydrogen-bond supramolecular hydrogels as efficient precursors in the preparation of freestanding 3D carbonaceous architectures containing BCNO nanocrystals and exhibiting a high CO2/CH4 adsorption ratio

Abstract Oxygen-enriched boron carbonitrides – known as boron carbon oxinitrides, BCNOs – have exhibited remarkable properties with numerous works reporting on their performance as phosphors and some few ones as H 2 -adsorbents. However, the study of BCNOs capability for CO 2 uptaking has yet to be achieved. Herein, we have designed a simple process for preparation of freestanding three-dimensional (3D) BCNO structures via pyrolysis of supramolecular gels formed by H-bonding of melamine, boric acid and glucose. The 3D porous materials obtained by pyrolysis of supramolecular gels containing glucose exhibited a seaweed-like 3D structure formed by BCNO nanocrystals embedded within a carbonaceous matrix with a certain content of amorphous hydrogenated carbon. The particularly narrow porosities exhibited by these samples proved effective for CO 2 adsorption with uptakes of up to ca. 1.8 mmol/g at 25 °C. More interestingly, those samples prepared with high concentration of glucose behaved as molecular sieves and exhibited an excellent performance for CO 2 –CH 4 separation, especially at low pressures with k H values of up to 1.04∙10 3 .