%0 Journal Article
%T Au汛ˋ每Ov每Ti3+ Interfacial Site: Catalytic Active Center toward Low-Temperature Water Gas Shift Reaction
%J -
%D 2019
%R https://doi.org/10.1021/acscatal.8b04913
%X The electronic metal每support interaction (EMSI) plays a crucial role in promoting catalytic performance toward interface electronic structure sensitive reactions, such as the low temperature water gas shift reaction (LT-WGSR). Herein, a mixed metal oxide support (ZnTi-MMO) was obtained via structural topological transformation from a zinc每titanium layered double hydroxides (ZnTi-LDHs) precursor, which was used for the immobilization of Au nanoparticles (NPs). Following a reduction pretreatment at 300 ∼C in a H2 atmosphere, the resulting optimal catalyst [email protected]2每x/ZnO(H300) exhibits a WGSR rate up to 0.15 molco molAu每1 s每1, which is at a high level compared with previously reported gold-based catalyst systems. Ac-HAADF-STEM combined with CO pulse chemisorption measurements verifies a TiO2每x overlayer on the surface of Au NPs. Quasi in situ XPS, EPR, in situ EXAFS, and in situ DRIFTS demonstrate the formation of interface dual-active-site (Au汛ˋ每Ov每Ti3+; Ov: oxygen vacancy) based on electron transfer from the TiO2每x overlayer to Au atoms, in which the electron-enriched Au汛ˋ species enhance CO chemisorption while Ov每Ti3+ accelerates the dissociation of the H2O molecule, accounting for the largely enhanced catalytic activity and stability of [email protected]2每x/ZnO(H300) compared with the traditional Au/TiO2 system. In situ/operando EXAFS further confirms that Au汛ˋ每Ov每Ti3+ interfacial site serves as the optimal active site toward WGSR: both Au汛ˋ species and Ov directly participate in the rate-determining step of LT-WGSR (water dissociation). The discovery and identification of the interfacial active site in this system can be extended to other metal catalysts with largely promoted performance in heterogeneous catalysis
%U https://pubs.acs.org/doi/10.1021/acscatal.8b04913