GETTERING OF HYDROGEN AND OXYGEN BY ALKALI-METAL GRAPHITE-INTERCALATION COMPOUNDS

Gettering of hydrogen and oxygen by alkali-metal graphite intercalation compounds, MC8 (M = K, Rb, and Cs), was investigated by the constant-volume closed method. The rate constants for hydrogen gettering k(H) are found to be in the order of RbC8 (approximately 10(-3) s-1) > KC8 (approximately 10(-4) s-1) greater than or similar to CsC8 (< 10(-6) s-1), while the rate constants for oxygen gettering k(O) are all within the range 0.2 X 10(-1)-1 x 10(-1) s-1 for MC8 studied. The ratio k(O)/k(H) is found to be 34, 69, and more than 5.2 X 10(4) for KC8, RbC8, and CSC8, respectively, which indicates that CSC8 has a large pumping selectivity for oxygen in a hydrogen-rich atmosphere.