Novel Mesoporous and Multilayered Yb/N-Co-Doped CeO₂ with Enhanced Oxygen Storage Capacity

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Ceria (CeO₂) is a crucial material for catalysis due to its oxygen storage capacity (OSC).
• Improving OSC is vital for applications like three-way catalysts.
• Mesoporous structures can enhance surface area and reactivity.

Purpose of the Study:

• To synthesize mesoporous ceria with a fluorite structure.
• To investigate the effect of ytterbium (Yb) and nitrogen (N) doping on ceria's OSC.
• To establish structure-performance relationships for doped ceria.

Main Methods:

• Solvothermal synthesis followed by calcination to create mesoporous CeO₂.
• Quantification of OSC using hydrogen temperature-programmed reduction (H₂-TPR).
• Partial least squares (PLS) method to correlate doping, lattice parameters, oxygen vacancies, and OSC.

Main Results:

• Undoped CeO₂ exhibited an OSC of 0.115 mmol O₂/g.
• Doping with 5 mol.% Yb(NO₃)₃∙5H₂O increased OSC to 0.222 mmol O₂/g.
• Further enhancement to 0.274 mmol O₂/g was achieved with 20 mol.% triethanolamine (N doping).
• Doping increased non-stoichiometric oxygen vacancies (V_O) and reducible Ceⁿ⁺ ions.

Conclusions:

• Yb and N co-doping effectively enhances the OSC of mesoporous ceria.
• The enhanced OSC is attributed to increased oxygen vacancies and improved Ce³⁺/Ce⁴⁺ redox cycling.
• PLS analysis provided quantitative structure-performance relationships.