Anchoring Monolayer TiO_x Nanosheets on Gold Nanoparticles Enhances Catalytic Activity for CO Oxidation Depending on...

Catalytic performance of supported gold catalysts is governed by the contact structure between Au nanoparticles (NPs) and reducible metal oxides. In this study, we constructed an Au-TiO_x interface by decorating supported Au NPs with monolayer titania nanosheets (TNS). We report a support-dependent formation of the interface between Au and TiO_x thin overlayer. For Au/SiO₂, TNS adsorption followed by calcination significantly enhanced CO oxidation activity. In contrast, for Au/CeO₂, TNS adsorption without calcination markedly improved the activity. Spectroscopic analyses revealed that cationic Au and Ti³⁺ species increased after TNS adsorption for Au/CeO₂ and the subsequent calcination for Au/SiO₂, respectively, suggesting the formation of Au-TiO_x interface. X-ray photoelectron spectroscopy (XPS) showed that TNS adsorption on CeO₂ induced a slight increase in Ce³⁺ species, consistent with Ce-O-Ti anchoring via interaction between surface Ti-OH and Lewis acidic Ce⁴⁺ sites. The surface reaction between TNS and redox-active CeO₂ gives Au-TiO_x contact structures, whereas nonreducible SiO₂ requires calcination. Moreover, the TiO_x overlayer derived from TNS was more oxygen-deficient than that obtained by impregnation of Ti species. This work demonstrates that the use of monolayer TNS is advantageous for the formation of active Au-TiO_x interface and rich oxygen vacancies.