  Exotic and robust metallic surface states of topological insulators (TIs)
have been expected to provide a promising platform for novel surface chemistry
and catalysis. However, it is still an unprecedented field how TIs affect the
activity of catalysts. In this work, we study the effects of topological
surface states (TSSs) on the activity of transition metal clusters (Au, Ag, Cu,
Pt, and Pd), which are supported on a TI Bi2Se3 substrate. It was found the
adsorption energy of oxygen on the supported catalysts can be always enhanced
due to the TSSs. However, it does not necessarily mean an increase of the
activity in catalytic oxidation reaction. Rather, the enhanced adsorption
behavior in the presence of TSSs exhibits dual effects, determined by the
intrinsic reactivity of these catalysts with oxygen. For the Au case, the
activity of catalytic oxidation can be improved because the intrinsic binding
between Au and O is relatively weak. In contrast, a negative effect is found
for the Pt and Pd clusters since the intrinsic binding of Pt and Pd with oxygen
is too strong. We also found that the effect of TSSs on the activity of
hydrogen evolution reaction (HER) is quite similar, i.e. the metals with
original weak reactivity can gain a positive effect from TSSs. The present work
can pave a way for more rational design and selection of catalysts when using
TIs as substrates.
