UCLA

We use first-principles calculations and chemical bonding analysis to investigate how the adsorption on topological insulators modifies the chemical properties of thin films of catalytic metals, Pt, Au, and Ag. Topological surface states (TSSs) present at the Fermi level and coinciding with the physical termination of the topological insulators are found to interact with the metal monolayers and themselves become modified by the adhesion, particularly in the case of relatively stronger Pt adhesion. The properties of the monolayers are, in turn, affected by the interaction with TSS. Specifically, the adsorption strengths of the typical catalytic intermediates exhibit important shifts that can lead to an enhanced catalytic reactivity. H is an adsorbate present in the hydrogen evolution reaction (HER) and thermal dehydrogenation, and its adsorption energy is often used as a descriptor of the activity. The bonding to the supported Pt film is slightly weaker than that to the Pt metal due to TSS involvement. This is expected to place the system closer to the apex of the catalytic volcano for the HER than Pt itself. The adsorption of CO on Au and Ag is, in contrast, strengthened by TSS, potentially opening an opportunity to electrochemically reduce COa process not achieved by bulk Au or Ag electrodes. We note that all interactions with the TSS play a perturbative role in binding. The metals provide electronic states deep below the Fermi level, facilitating the bonding mechanisms notorious for these adsorbates on the corresponding metals. TSS supply additional bonding and/or antibonding effects that are relatively weak but likely consequential for catalysis.