Facet-Dependent Oxidative Strong Metal-Support Interactions of Pd-TiO2 via In Situ TEM.

The strong metal-support interaction (SMSI) is widely used in supported metal catalysts and extensive studies have been performed to understand the SMSI. Although considerable progress has been achieved, the surface structure of the support, as an important influencing factor, is usually ignored. Here, we report a facet-dependent SMSI of Pd-TiO 2 in oxygen by using in situ atmospheric pressure TEM. It is revealed that the Pd NPs supported on TiO 2 (101) and (100) surfaces showed encapsulation. In contrast, no such cover layer was observed in Pd-TiO 2 (001) catalyst under the same conditions. This facet-dependent SMSI, which originates from the different surface structure of the support, was demonstrated in a probe reaction of methane combustion catalyzed by Pd-TiO 2 . Our discovery of the oxidative facet-dependent SMSI gives direct evidence of the important role of the support surface structure in SMSI and provides a new way to tune the interaction between metal NPs and the support as well as catalytic activity.