Infrared study of boron–carbon chemical bonds in boron-doped activated carbon

We report Fourier transform infrared spectroscopy (FTIR) studies of boron-doped activated carbons. The functional groups for hydrogen adsorption in these materials, the boron-related chemical bonds, are studied by comparing the activated carbon materials with and without boron doping. The activated carbon materials are prepared from corncob biomass waste feedstock through KOH activation, yielding adsorbents with a high surface area. Boron atoms are doped into the activated carbon by vapor deposition of decaborane up to a solubility of 6.8 wt.%. Extra boron atoms (2–3 wt.%) are located on the surface of the carbon matrix. Results from conventional FTIR show serious spectral broadenings and band overlaps. To overcome the spectral broadenings and band overlaps, the sample concentration is reduced to a very low weight percent (0.03%) of activated carbon in KBr, and spectra are acquired by using microscopic FTIR. Activated boron carbide is used as a reference material to validate the boron–carbon bond in the nanoporous materials. For activated carbon doped via vapor deposition of decaborane, the substitutions of carbon atoms with boron atoms is confirmed using microscopic FTIR through the appearance of boron–carbon bonds, although it cannot be observed with conventional FTIR.