The ground state structures and spectra of Ag20 clusters and the adsorption to carbon monoxide

• Published in: Materials chemistry and physics 2021-11, Vol.273, p.125134, Article 125134
• Main Authors: shen, Xu-Ying, Die, Dong, Yang, Jian-Ping, Guo, Jian-Jun
• Format: Article
• Language: English
• Subjects: Adsorption; Ag20 cluster; Carbon monoxide; Cations; Clusters; CO adsorption; Density functional theory; Ground state; Infrared spectra; Isomers; Photoelectrons; Raman spectra; Spectrum; Tetrahedra; The ground state structure
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.125134

The most stable structures and spectra of neutral, anionic and cationic Ag20 clusters have been studied by using density functional theory in conjunction with an unbiased CALYPSO structure searching method. Structural searches indicate that the regular tetrahedron which was widely regarded as the ground-state of neutral Ag20 cluster is a low-lying isomer. Several new isomers with lower energy than the regular tetrahedron were found in geometry optimizations. The ground state structures of neutral and anionic Ag20 cluster are confirmed by the optical absorption and photoelectron spectra. On the other hand, the investigation of CO adsorption on Ag20 clusters shows that CO adsorption on anionic Ag20 cluster is stronger than that on neutral and cationic Ag20 clusters. The lowest energy structure of anionic Ag20 cluster can bind CO molecular number up to 19. The adsorption of CO on Ag20 clusters significantly changes the Infrared spectra of neutral and cationic Ag20 clusters and the Raman spectrum of anionic Ag20 cluster. Raman scattering intensity of CO adsorbed on Ag20 cluster was enormously enhanced. The experimental and calculated optical-absorption spectra of Ag20 nanocluster and CO adsorption on Ag20− nanocluster. [Display omitted] •The regular tetrahedron which was universally regarded as the ground-state of Ag20 nanocluster is a low-lying isomer.•The ground state structure of anionic Ag20 nanoclusters is confirmed by ultraviolet photoelectron spectrum.•The adsorption capacity of anionic Ag20 nanocluster to CO is stronger than that of neutral and cationic Ag20 nanoclusters.•Intensity of IR and Raman spectra can be greatly enhanced when CO is absorbed on Ag20 nanoclusters.