SUPER ACTIVATED CARBON CONTAINING SUBSTITUTIONAL BORON: SYNTHESIS, CHARACTERIZATION AND APPLICATIONS IN HYDROGEN STORAGE

Open Access
Author:
JEONG, YOUMI
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
February 10, 2010
Committee Members:
  • T C Mike Chung, Dissertation Advisor
  • T C Mike Chung, Committee Chair
  • Paul C Painter, Committee Member
  • Michael Anthony Hickner, Committee Member
  • Harold Harris Schobert, Committee Member
Keywords:
  • hydrogen storage
  • boron substitution
Abstract:
Boron substituted carbon material (BCx) is a new class of activated carbon that contains substitutional boron homogeneously distributed throughout the entire hexagonal carbon structure with three covalent bonds. The BCx produced with porous structures has been suggested as a promising candidate for onboard hydrogen storage application. Nanoporous BCxs with varing boron content, surface area, and morphology were synthesized. The chemistry involves a designed boron containing precursor, i.e. poly(diethynylphenylborane chloride) containing in situ formed inorganic salts that serve as the templates for forming the porous morphology. The MAS solid state 11B NMR were conducted to reveal the boron content and electron delocalization in the fused hexagonal ring structures. Morphologies including pore size and distribution were examined by high resolution TEM, FE-SEM, XRD, and surface area and pore size distribution were examined by nitrogen and carbon dioxide sorption method. One BC12 with 780 m2/g of surface area showed an extended fused hexagonal ring structure with boron puckered curvature. This off-planar boron moiety maintains its high acidity (electron deficiency), due to limited π electron delocalization, and serves as an internal p-type dopant for activating BCx surfaces that exhibit super-activated interactive properties. Such activation can enhance both hydrogen binding energy (up to 13 kJ/mole) and adsorption capacity. Additionally, the nanoporous BCx played a unique role in metal particles dispersion in the BCx support. The disposed metal compounds are stabilized by the substitutional boron moiety of BCx support and therefore maintained highly monodisperse and small particles without additional surface stabilizers. This stabilization is due to the interaction between the d orbital of transition metal atom and the p orbital of boron atom on the BCx surface, which enable a 0.7 wt.% Pt/BC12 to show the catalytic activity in the hydrogen physisorption system even with extremely low levels of metal content.