Manipulating Atomic Structures at the Au/TiO₂ Interface for O₂ Activation

Abstract

The metal/oxide interface has been extensively studied due to its importance for heterogeneous catalysis. However, the exact role of interfacial atomic structures in governing catalytic processes still remains elusive. Herein, we demonstrate how the manipulation of atomic structures at the Au/TiO 2 interface significantly alters the interfacial electron distribution and prompts O 2 activation. It is discovered that at the defect-free Au/TiO 2 interface electrons transfer from Ti 3+ species into Au nanoparticles (NPs) and further migrate into adsorbed perimeter O 2 molecules (i.e., in the form of Au−O−O−Ti), facilitating O 2 activation and leading to a ca. 34 times higher CO oxidation activity than that on the oxygen vacancy (V o )-rich Au/TiO 2 interface, at which electrons from Ti 3+ species are trapped by interfacial V o on TiO 2 and hardly interact with perimeter O 2 molecules. We further reveal that the calcination releases those trapped electrons from interfacial V o to facilitate O 2 activation. Collectively, our results establish an atomiclevel description of the underlying mechanism regulating metal/oxide interfaces for the optimization of heterogeneous catalysis.

Catalytic CO Oxidation by O2 Mediated with Single Gold Atom Doped Titanium Oxide Cluster Anions AuTi2O4–6−

“…Au/TiO 2 has become one of the best studied gold catalysts in CO oxidation since the breakthrough made by Haruta [12,13] . Extensive research interests have been devoted to exploring the unexpected reactivity of Au/TiO 2 , [26–28,46,47] and the nature of active sites to induce O 2 activation is one of the focuses because of the strong O−O bond (5.16 eV). It is generally accepted that the active sites are localized on the interface between Au and TiO 2 , thus, many strategies have been proposed to engineer and build more effective gold‐support interface in order to improve the reactivity and selectivity toward a desirable product [43,44,48,49] .…”

“…It is generally accepted that the active sites are localized on the interface between Au and TiO 2 , thus, many strategies have been proposed to engineer and build more effective gold‐support interface in order to improve the reactivity and selectivity toward a desirable product [43,44,48,49] . However, it is a big challenge to have an understanding on the exact functionality of active sites and it is difficult to regulate the chemical surroundings of a local site at the electronic structure level in real‐life conditions [26] . Thus, related fundamental studies are of scientific and practical importance to provide suggestive information to tailor the active sites.…”

“…[43,44,48,49] However, it is a big challenge to have an understanding on the exact functionality of active sites and it is difficult to regulate the chemical surroundings of a local site at the electronic structure level in real-life conditions. [26] Thus, related fundamental studies are of scientific and practical importance to provide suggestive information to tailor the active sites. In gas-phase studies, for catalytic CO oxidation by O 2 mediated with gold-containing HMOCs, [16,17,22] gold was reinforced to function as a powerful electron reservoir to promote CO oxidation and O 2 activation.…”

“…Catalytic CO oxidation by O 2 mediated with Au-TiÀ O HMOCs is of great importance to uncover the catalytic behaviors of Au/ TiO 2 , one type of the best studied gold catalysts in condensedphase studies until now. [25][26][27][28][29][30] However, such catalysis in the gas phase has been scarcely reported, [17] thus, the nature of the active sites and the essence of Au-TiO 2 interaction to drive the catalysis are far from clear.…”

“…CO oxidation is also one type of the best studied catalytic reactions in gas phase, [1,14,15] and gold‐containing heteronuclear metal oxide clusters (HMOCs) [16–24] are promising models for the active sites on oxide supported gold. Catalytic CO oxidation by O 2 mediated with Au‐Ti−O HMOCs is of great importance to uncover the catalytic behaviors of Au/TiO 2 , one type of the best studied gold catalysts in condensed‐phase studies until now [25–30] . However, such catalysis in the gas phase has been scarcely reported, [17] thus, the nature of the active sites and the essence of Au‐TiO 2 interaction to drive the catalysis are far from clear.…”