The effect of CNTs on structures and catalytic properties of AuPd clusters for H2O2 synthesis

Abstract

The structures and catalytic properties of AuPd clusters supported on carbon nanotubes (CNTs) for H₂O₂ synthesis have been investigated by means of density functional theory calculations. Firstly, the structures of AuPd clusters are strongly influenced by CNTs, in which the bottom layers are mainly composed of Pd and the top layers are a mix of Au and Pd due to the stronger binding of Pd than Au on CNTs. Especially, it is found that O₂ adsorption on the Pd/CNTs interfacial sites is much weaker than that on the only Pd sites, which is in contrast to transition metal oxide (for example TiO₂, Al₂O₃, CeO₂) supported metal clusters. Furthermore, Pd ensembles on the interfacial sites have far superior catalytic properties for H₂O₂ formation than those away from CNT supports due to the changes in electronic structures caused by the CNTs. Therefore, our study provides a physical insight into the enhanced role of carbon supports in H₂O₂ synthesis over supported AuPd catalysts.