Super-activated carbon containing substitutional boron for hydrogen storage

We have developed a versatile method to prepare a broad range of porous BC_x materials by using a boron-containing polymer precursor with some inorganic additives (pore-forming templates). Some resulting amorphous BC_x materials (pyrolysis at 600-800 °C) show controllable micropore and mesopore structures with high surface area, and containing up to 12% B content with acidic B moieties. The combination provides super-activated surfaces for physical interactions with various molecules. A porous BC₆ material exhibits a reversible hydrogen physisorption capacity of 0.5 and 3.5 wt% H₂ per 500 m²/g surface area of the material at 293 and 77 K, respectively, under moderate hydrogen pressure (<100 bars). Both values are >3 times higher than H₂ absorption capacities in the corresponding carbonaceous materials. The physisorption results were further warranted by absorption isotherms, indicating a H₂ binding energy of 10-20 kJ/mole, significantly higher than the 4 kJ/mole reported on most graphitic C surfaces.