Tuning the f Band for Enhanced Surface Redox in Strained Rare Earth Oxides

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Reducible rare earth oxides (REO) are vital catalysts due to their 4f band-governed redox properties.
• Directly correlating REO 4f band structure with catalytic activity is challenging due to electron manipulation complexities.

Purpose of the Study:

• To investigate the effect of tensile strain on the 4f electronic structure of REOs.
• To demonstrate strain-induced modulation of surface redox properties and catalytic activity.

Main Methods:

• Fabrication of atomically flat ceria ultrathin films.
• Application of up to 7% biaxial tensile strain.
• Time-resolved ambient-pressure X-ray photoelectron spectroscopy (TR-APPES).
• Density functional theory (DFT) calculations.

Main Results:

• Tensile strain effectively narrows the 4f band gap and activates surface oxygen.
• A five-fold increase in surface reaction kinetics was observed under strain.
• DFT calculations confirmed reduced energy barriers for catalytic steps due to narrowed 4f-2p band gap.

Conclusions:

• The 4f electronic structure is a critical descriptor for rare earth oxide catalysis.
• Atomically flat model systems are effective for studying strain effects on catalysis.
• Tensile strain offers a viable route to enhance REO catalytic performance.