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 kH are found to be in the order of RbC8 (∼10−3 s−1)≳KC8 (∼10−4 s−1)≫CsC8 (<10−6 s−1), while the rate constants for oxygen gettering kO are all within the range 0.2×10−1–1×10−1 s−1 for MC8 studied. The ratio kO/kH is found to be 34, 69, and more than 5.2×104 for KC8, RbC8, and CsC8, respectively, which indicates that CsC8 has a large pumping selectivity for oxygen in a hydrogen-rich atmosphere.