Performance of Carbon Hydrogen Storage Materials as a Function of Post-Production Thermal Treatment

High-surface-area activated carbons for hydrogen storage were investigated as a function of post-synthesis surface treatment. Thermal treatment of the initial carbon in high vacuum at temperatures 200-1000 \r{ }C leads to materials with significantly different surface chemistries and hydrogen storage capacities. Results from nitrogen pore-structure analyses, FT-IR spectroscopy before and after the treatment, and thermogravimetric analysis and mass spectroscopy of volatile reaction products during treatment, are reported. For treatment at 600 \r{ }C, excess hydrogen adsorption at 80 K and 303 K is found to be 20-30{\%} higher than for the untreated sample. At temperatures below 450 \r{ }C, volatiles are mostly water and air; volatiles above 450 \r{ }C are mostly carbon dioxide and carbon monoxide. The results are interpreted as that high-temperature treatment produces materials with a large fraction of high-binding-energy sites.