A density functional theory study of sulfur adsorption on Ag–Au nanoalloys

Abstract

The adsorption properties of nanoalloys can be tuned not only by size and morphology, but also by composition and chemical ordering. In this work, a density functional theory approach is applied to investigate the adsorption properties of neutral sulfur (S) on Ag–Au nanoalloys changing with the size, morphology, composition, and chemical ordering. It is proved that the adsorption strength of S on the Agn and Agn−1Au (n=13, 55, and 147) clusters decreases with increasing the size, which is elucidated by the electronic contribution of p orbital of S. It is also verified that the adsorption strength of S on the Ag42Au13 and Ag55 clusters follows the order of cuboctahedral (Cubo)>icohedral (Ico)>decahedral (Dec), indicating that the Cubo-structured Ag42Au13 and Ag55 clusters possess high affinity toward S. In addition, it is found that the adsorption strength of S increases with increasing the content of Au for S on the Ag42Au13, Ag54Au and Ag55 clusters changing with the composition. Moreover, it is also found that the adsorption properties of S on Ag42Au13 can be tuned by changing its chemical ordering. Among these considered clusters, the Cubo-structured Ag42Au13 cluster exhibits the best affinity toward S, due to its excellent electronic and geometric response to the adsorption of S. Our theoretical results are expected to provide new guidelines for designing and preparing effective and low-cost biosensor for detecting S based on the Ag–Au nanoalloys.