Hydrothermal Embedding of Pd Single Atoms Into SnO₂ for Efficient CO Oxidation

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• CO oxidation is crucial for environmental remediation and industrial processes.
• Developing highly active and stable catalysts, particularly for low-temperature CO oxidation, remains a significant challenge.
• Palladium (Pd) based catalysts are effective but prone to deactivation via CO poisoning.

Purpose of the Study:

• To develop a novel strategy for fabricating highly efficient and stable Pd/SnO2 catalysts for CO oxidation.
• To elucidate the structure-activity relationships governing the enhanced catalytic performance.
• To establish a new design principle for single-atom catalysts (SACs).

Main Methods:

• Hydrothermal embedding strategy to synthesize Pd/SnO2 catalysts.
• Characterization using experimental techniques (e.g., spectroscopy, microscopy).
• Theoretical calculations (e.g., Density Functional Theory) to understand reaction mechanisms.

Main Results:

• The hydrothermally treated Pd/SnO2-H catalyst exhibited a three-fold increase in CO oxidation rate compared to the fresh Pd/SnO2-F catalyst, using only 0.15 wt.% Pd.
• Hydrothermal treatment led to the formation of single-atom Pd sites (Pd1) embedded within the SnO2 lattice.
• Lattice-incorporated Pd1 sites enhanced Pd-SnO2 interaction, facilitated O2 activation via a Mars-van Krevelen pathway, and weakened CO adsorption, suppressing CO poisoning.

Conclusions:

• Hydrothermal embedding is an effective strategy to create highly active and stable single-atom Pd catalysts on SnO2.
• Lattice incorporation of single-atom Pd into reducible oxide supports offers a promising approach to simultaneously enhance redox kinetics and mitigate catalyst poisoning.
• This work provides a new design principle for developing advanced single-atom catalysts for various chemical transformations.