Electronic properties and adsorption mechanism of Ru-doped copper clusters towards CH3OH molecule: A DFT investigation

In this study, we have investigated the stability and electronic properties of the CunRu (n = 2-10) nanoclusters and their interaction with the CH3OH molecule without and with the presence of O2 molecule by using DFT calculations with TPSS/SDD/6-311g(d,p) level of theory. Based on the second energy difference (Delta 2E), the re-sults reveal that the CunRu (n = 4, 6 and 8) clusters are relatively more stable than their neighboring clusters. The values obtained for the Fukui function (f -) proves that the Ru atom in the CunRu clusters is an excellent adsorption site for the molecules. The interaction of the CunRu clusters with CH3OH molecule exhibits that the Ru atom is the preferred adsorption site for the CH3OH molecule, where the O atom of the CH3OH molecule is strongly chemisorbed onto the Ru site of the clusters, forming a strong bond between the Ru and O atoms. The copper sites of the clusters were found less preferred for the adsorption of CH3OH, and the complexes formed between both species are less stable than those obtained from the CH3OH chemisorption over the Ru site of the clusters. The interaction of CH3OH with the clusters was also evaluated in an oxidizing environment, and the results obtained reveal that the molecule is greatly chemisorbed over the ruthenium site with adsorption energies which vary from - 1.18 to - 2.05 eV. In the presence of the oxygen, the gap energy of the clusters was sharply changed after their interactions with the CH3OH molecule, suggesting that these clusters can easily detect the above molecule with great sensitivity. Therefore, the presence of the oxygen not only does not prevent the adsorption process, but it considerably promotes the CH3OH chemisorption onto the ruthenium site of the clusters and therefore significantly rises their sensitivity performance. In conclusion, the CunRu clusters could be employed as effective nanosensors for the CH3OH molecule detection.

Automated summary

In this study, the stability and electronic properties of CunRu (n = 2-10) nanoclusters and their interaction with the CH3OH molecule were investigated. The results showed that CunRu (n = 4, 6, and 8) clusters are more stable than their neighboring clusters. The Ru atom in the CunRu clusters was found to be an ideal adsorption site for CH3OH molecule.