Facet-dependent adsorbate-mediated strong metal-support interaction in Ni/TiO₂

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Adsorbate-mediated strong metal-support interaction (A-SMSI) is crucial for catalysis, but its formation mechanisms and control are not fully understood.
• Understanding A-SMSI is key to designing efficient catalysts for reactions like CO2 hydrogenation.

Purpose of the Study:

• To elucidate the atomic-level mechanism of A-SMSI formation during CO2 hydrogenation.
• To investigate the facet-dependent behavior of A-SMSI on Ni/TiO2 model catalysts.
• To demonstrate how facet-dependent A-SMSI can be used to control catalytic selectivity.

Main Methods:

• In situ environmental transmission electron microscopy (ETEM) to visualize A-SMSI formation at the atomic level.
• In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray absorption spectroscopy (XAS) for mechanistic insights.
• Density functional theory (DFT) calculations to support experimental findings.

Main Results:

• Distinct TiO2-x overlayer formation on different Ni/TiO2 facets ({100}, {101}, {001}) was observed.
• A dual induction mechanism involving adsorbates in TiO2-x formation and stabilization was revealed.
• TiO2-x overlayers modulated electronic properties and stabilized key intermediates (COOH*).

Conclusions:

• Facet-dependent A-SMSI formation was directly visualized and mechanistically understood.
• Precise control over CO2 hydrogenation selectivity (CH4 or CO) was achieved by tuning catalyst facets.
• This work provides a framework for designing oxide-supported catalysts with tailored interfacial properties.