CO Oxidation Facilitated by Robust Surface States on Au-Covered Topological Insulators

Surface states-the electronic states emerging as a solid material terminates at a surface-are usually vulnerable to contaminations and defects. The robust topological surface state(s) (TSS) on the three-dimensional topological insulators provide a perfect platform for exploiting surface states in less stringent environments. Employing first-principles density functional theory calculations, we demonstrate that the TSS can play a vital role in facilitating surface reactions by serving as an effective electron bath. We use CO oxidation on gold-covered Bi2Se3 as a prototype example, and show that the robust TSS can significantly enhance the adsorption energy of both CO and O-2 molecules, by promoting different directions of static electron transfer. The concept of TSS as an electron bath may lead to new design principles beyond the conventional d-band theory of heterogeneous catalysis.