(185j) Selective Adsorption of Xenon and Krypton on Ni-Co Metal Surface: A Density Functional Theory Study

The separation of xenon (Xe) and krypton (Kr) is critical for several industrial applications such as spent nuclear fuel processing. While several adsorbents, including activated carbon, zeolite, and metal-organic frameworks (MOF), can be used for the separation, almost all of them have their own limitations, for instance, poor Xe/Kr selectivity or instability of functional groups. Therefore, we investigated the possibility of using metals, including fcc-Ni, hcp-Co and hcp-Co₃Ni, as the adsorbent for the separation. Density function theory (DFT) calculations show that metal surfaces have higher affinity with Xe than Kr. Local density of states (LDOS) calculations further reveal the interaction between p orbitals of rare gas atoms and occupied d orbitals of metals. The adsorption energy of Xe is up to 65% higher than that of Kr, because p orbitals of Xe have more similar energy with d orbitals of metals than Kr, thus providing more effective combination.