Probing Prismatic/Basal Surfaces of Carbon Materials\nupon Graphitization by Gas Adsorption, TPD, and XPS

The\nprismatic and basal plane surfaces of carbon materials dictate\nmost of their anisotropic physicochemical properties. For many applications\nwhere interfacial interactions are key, high-temperature treatments\nare performed to achieve their graphitization. Such treatment changes\nedge and basal plane configuration, impacting the energetical behavior\nof the carbon surfaces, particularly for carbon nanomaterials, with\nconsequences for their properties. Therefore, efforts should be devoted\nto probing the prismatic and basal plane surfaces of such materials\nto understand their surface properties for the development of high-performance\ncarbon materials. Herein, we investigate the effect of high-temperature\ngraphitization (3073 K) on the structural, textural, chemical, and\nmagnetic properties of graphitic carbon nanomaterials presenting different\nprismatic/basal surfaces. The evolution of the prismatic/basal surfaces\nhas been probed by nitrogen adsorption, temperature-programmed desorption,\nand X-ray photoelectron spectroscopy (XPS). Although these three techniques\nare in agreement for the starting materials, they diverge in the case\nof materials that have undergone thermal annealing. This is linked\nin particular to the formation of loops following the heat treatment,\nwhich are identified as belonging to the prismatic surface by XPS\nand modified the N<sub>2</sub> adsorptive potentials. Formed small\nvacancies on closed loops and nonperfect closure of certain loops\ncan contribute to the accumulation of very reactive defects at the\nloop level. The thermal annealing also has a pronounced influence\non the magnetic properties of these materials. Interestingly, we show\nthat a positive correlation exists between the spin density of the\nannealed graphitic carbons and their prismatic and basal surfaces.