Porous\nGraphitic Carbons Containing Nitrogen by Structuration\nof Chitosan with Pluronic P123

Abstract

Using\nPluronic P123 as a structure-directing agent and chitosan\nas a carbon precursor, different porous carbons with remarkable morphologies\nsuch as orthohedra or spheres with diametrically opposite holes are\nobtained. These particles of micrometric size are constituted by the\nstacking of thin sheets (60 nm) that become increasingly bent in the\nopposite sense, concave in the upper and convex in the bottom hemispheres,\nas the chitosan proportion increases. TEM images, after dispersion\nof the particles by sonication, show that besides micrometric graphene\nsheets, the material is constituted by nanometric onion-like carbons.\nThe morphology and structure of these porous carbons can be explained\nbased on the ability of Pluronic P123 to undergo self-assembly in\naqueous solution due to its amphoteric nature and the filmogenic properties\nof chitosan to coat Pluronic P123 nanoobjects undergoing structuration\nand becoming transformed into nitrogen-doped graphitic carbons. XPS\nanalysis reveals the presence of nitrogen in their composition. These\nporous carbons exhibit a significant CO₂ adsorption capacity\nof above 3 mmol g^–1 under 100 kPa at 273 K attributable\nto their large specific surface area, ultraporosity, and the presence\nof basic N sites. In addition, the presence of dopant elements in\nthe graphitic carbons opening the gap is responsible for the photocatalytic\nactivity for H₂ generation in the presence of sacrificial\nelectron donors, reaching a H₂ production of 63 μmol\ng^–1 in 24 h.