Theoretical insights on the influence of Au core in Aux@Pdy for improving HCOOH dissociation

Abstract

The core–shell bimetallic catalysts have unique catalytic activity due to the synergistic effect of the different elements. In this study, HCOOH dissociation on Au3@Pd1 and Au2@Pd2 has been investigated by using the density functional method. The results indicated that compared with pure Pd, the adsorption of the intermediates on the core–shell structures is strengthened by the introduced Au core. Strain effect plays an important role for the adsorption strength, which is also confirmed by the d band center. Compared with Au3@Pd1, Au2@Pd2 has better catalytic activity in the dissociation of HCOOH to produce H2. The rate determining step is bi-HCOO → mono-HCOO, which is also supported by the turnover frequency calculations for H2production. In addition, the calculated turnover frequency shows that the order of the rate of H2production is Au2@Pd2 > Au3@Pd1 > Pd(111), in agreement with the order of the catalytic activity from the energy barrier at the rate determining step for the three catalysts. This work provides insights concerning the influence of Au core on the catalytic activity at the atomic level and offers practical guidelines for the design of highly efficient catalysts.

Keywords

• HCOOH dissociation
• Au@pd core–shell structure
• Reaction mechanism
• Turnover frequency