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 Bi(2)Se(3) 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.