Effects of carbonization atmosphere and subsequent oxidation on pore structure of carbon spheres observed by scanning tunneling microscopy

Abstract

The surface of carbon spheres was studied by using field-emission scanning electron microscopy and scanning tunneling microscopy paying particular attention to the effects of atmosphere during carbonization and of subsequent oxidation on shape and size of the entrance of micropores. Commercial spheres of glasslike carbon prepared by carbonization of phenol resin spheres in either N 2 or CO 2 atmosphere were subjected to the oxidation by immersing into nitric acid and then heating in air at 400°C. The size distribution of pore entrance at nanoscopic scale was determined from scanning tunneling microscope images. Carbon spheres prepared in CO 2 atmosphere had predominantly ultramicropores, but those prepared in N 2 had a very low porosity. The behavior during the oxidation process in air was found to be quite different on these two carbon spheres; spheres carbonized in N 2 were oxidized heterogeneously, but those in CO 2 showed homogeneous oxidation, giving a high density of ultramicropores.

Controlled syntheses of carbon spheres in a swirled floating catalytic chemical vapour deposition vertical reactor

“…The type of spherical particle produced is dependent on the method of preparation, carbon source and the reaction conditions used [5][6][7][8][9][10][11][12]. These spherical materials have many potential applications, such as use as absorbents [14,15], as catalyst supports [16] or as anodes for use in lithium ion batteries [9,17].…”

Comparative study of carbon dioxide and nitrogen atmospheric effects on the chemical structure changes during pyrolysis of phenol–formaldehyde spheres

“…However, some very recent studies [5][6][7][8] have shown that, for porous carbons derived from PF resins of resol type, the pore characteristics, particularly the pore size distribution and the morphology of porous carbons, are significantly influenced by the atmospheric gases, such as carbon dioxide and nitrogen, during carbonization processes. Indeed, one of the authors (M.I.)…”

Carbon microspheres from ethanol at low temperature: Fabrication, characterization and their use as an electrocatalyst support for methanol oxidation

“…Carbon microspheres (CMSs) are of special interest because of their unique applications such as for catalyst supports [1][2][3][4][5], adsorbents [6,7], anode materials for lithium ion batteries [8][9][10] and templates for fabricating core-shell or hollow structures [11][12][13]. Many methods have been developed for the synthesis of spherical carbon materials.…”