Electronic Properties and CO(2)-Selective Adsorption of (NiB)(n) (n = 1~10) Clusters: A Density Functional Theory Study

In this study, we investigated the electronic properties and selective adsorption for CO(2) of nickel boride clusters (NiB)(n), (n = 1~10) using the first principles method. We optimized the structures of the clusters and analyzed their stability based on binding energy per atom. It was observed that (NiB)(n) clusters adopt 3D geometries from n = 4, which were more stable compared to the plane clusters. The vertical electron affinity, vertical ionization energy, chemical potential, and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap were calculated. Our results revealed that (NiB)(6) and (NiB)(10), with high chemical potential, exhibit a higher affinity for CO(2) adsorption due to a charge delivery channel that forms along the Ni→B→CO(2) path. Notably, (NiB)(10) demonstrated a more practical CO(2) desorption temperature, as well as a broader window for the selective adsorption of CO(2) over N(2). The density of states analysis showed that the enhanced CO(2) adsorption on (NiB)(10) can be attributed to the synergistic effect between Ni and B, which provides more active sites for CO(2) adsorption and promotes the electron transfer from the surface to the CO(2) molecule. Our theoretical results imply that (NiB)(10) should be a promising candidate for CO(2) capture.