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

Area of Science:

• Catalysis
• Materials Science
• Surface Chemistry

Background:

• Strong metal-support interaction (SMSI) is crucial in heterogeneous catalysis.
• The fundamental origin of SMSI, particularly the roles of surface energy and electron transfer, remains debated.
• Decoupling these factors in traditional catalysts is challenging.

Purpose of the Study:

• To investigate the driving force behind SMSI by minimizing charge transfer.
• To elucidate the mechanism of SMSI using a quasi-model catalyst system.
• To challenge the prevailing hypothesis that electron transfer is the primary cause of SMSI.

Main Methods:

• Fabrication of a TiO_x/Au/Al₂O₃ quasi-model catalyst with minimal TiO_x on Au nanoparticles.
• Application of high-temperature reduction-reoxidation treatment.
• Monitoring the wetting-dewetting behavior of TiO_x and its effect on adsorption capability.
• Assessing the negligible charge transfer between TiO_x and Au during the process.

Main Results:

• The TiO_x layer on Au nanoparticles exhibited a reversible wetting-dewetting process upon thermal treatment.
• This process led to a reversible suppression and recovery of adsorption capability.
• Crucially, electron transfer between TiO_x and Au was found to be negligible during these changes.
• The observed phenomena occurred independently of significant charge transfer.

Conclusions:

• Charge transfer is likely not the primary driving force for the occurrence of SMSI.
• The study provides experimental evidence supporting surface energy minimization as a potential dominant factor in SMSI.
• This work offers a deeper mechanistic understanding of SMSI, distinct from electron transfer effects.