Unraveling oxygen vacancy-driven catalytic selectivity and hot electron generation on heterointerfaces using...

Area of Science:

• Materials Science
• Chemical Engineering
• Surface Chemistry

Background:

• Heterogeneous catalysis relies on modulating oxide physicochemical properties for efficient reactions.
• Distinguishing the specific catalytic role of oxides is challenging due to complex interfaces and structures.

Purpose of the Study:

• To establish a model platform using well-aligned cerium oxide (CeO_x) nanowire arrays on platinum (Pt) catalysts.
• To systematically investigate and quantify the individual effects of oxide crystallinity and oxygen vacancy concentration on catalytic performance.

Main Methods:

• Fabrication of CeO_x nanowire arrays on Pt catalysts with controlled interfaces.
• Independent modulation of CeO_x crystallinity and oxygen vacancy concentration via vacuum annealing.
• Quantitative analysis of partial oxidation selectivity and hot electron generation during methanol oxidation.
• Density-functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Vacuum-annealed CeO_x/Pt catalysts showed 1.47x higher selectivity to methyl formate compared to unannealed counterparts.
• Chemicurrent yield was 2.12x higher for annealed CeO_x/Pt, indicating enhanced activity.
• Oxygen vacancies in CeO_x were identified as crucial for promoting charge transfer and enhancing selectivity.

Conclusions:

• The study successfully demonstrates a method to isolate and quantify the catalytic contribution of oxides in heterogeneous systems.
• Optimizing oxide properties, particularly oxygen vacancy concentration, is a key strategy for improving catalytic efficiency and selectivity.
• Enhanced charge transfer at the electron-accumulated interface, driven by oxygen vacancies, is the primary mechanism for improved performance in methanol oxidation.