Insight into the Origin of Strong Metal–Support Interaction Obtained on an Inverse TiOx/Au/Al2O3 Quasi-Model Catalyst

Strong metal-support interaction (SMSI) is one of the most important phenomena in the history of heterogeneous catalysis and has gained renewed attention in the past decade due to the emergence of various new types of SMSI. However, the origin of SMSI still remains in debate. Both minimizing surface energy and electron transfer have been regarded as the origin of SMSI because these two are hard to decouple in traditional supported metal catalysts. In this work, a TiOx/Au/Al2O3 quasi-model catalyst was fabricated by inversely depositing a minimal amount of TiOx on the surface of Au nanoparticles, where the charge transfer between TiOx and Au was minimized. As experimentally demonstrated, under high-temperature reduction-reoxidation treatment, the surface TiOx undergoes a wetting-dewetting process, accompanied by the reversible suppression and recovery of the adsorption capability, during which the electron transfer between TiOx and Au is negligible. This work suggests that charge transfer may not be the driving force for the occurrence of SMSI, contributing to a deeper understanding of the SMSI mechanism.