Investigating the structure of biomass-derived non-graphitising mesoporous carbons by electron energy loss spectroscopy in the transmission electron microscope and X-ray photoelectron spectroscopy

We have investigated the microstructure and bonding of two biomass-based porous carbon chromatographic stationary phase materials (alginic acid-derived Starbon ® and calcium alginate-derived mesoporous carbon spheres (AMCS)) and a commercial porous graphitic carbon (PGC), using high resolution transmission electron microscopy, electron energy loss spectroscopy (EELS), N2 porosimetry and X-ray photoelectron spectroscopy (XPS). The planar carbon sp 2 -content of all three material types is similar to that of traditional nongraphitising carbon although, both biomass-based carbon types contain a greater percentage of fullerene character (i.e curved graphene sheets) than a non-graphitising carbon pyrolysed at the same temperature. This is thought to arise during the pyrolytic breakdown of hexauronic acid residues into C5 intermediates. Energy dispersive X-ray and XPS analysis reveals a homogeneous distribution of calcium in the AMCS and a calcium catalysis mechanism is discussed. That both Starbon ® and AMCS, with high-fullerene character, show chromatographic properties similar to those of a commercial PGC material with extended graphitic stacks, suggests that, for separations at the molecular level, curved fullerene-like and planar graphitic sheets are equivalent in PGC chromatography. In addition, variation in the  Corresponding author. Tel:+44(0)113 3432369. Email: [email protected]