Spinel/Rock Salt Core/Shell High-Entropy Oxides for Selective CO₂ Hydrogenation.

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• High-entropy oxides (HEOs) offer exceptional stability due to configurational entropy.
• Catalytic activity in HEOs is often limited by the activity-stability trade-off and dynamic site regeneration issues.

Purpose of the Study:

• To develop a novel mixed-phase HEO catalyst with enhanced activity and stability.
• To address the limitations of traditional HEO catalysts in the reverse water gas shift (RWGS) reaction.

Main Methods:

• Designed a spinel/rock salt core/shell mixed-phase HEO catalyst.
• Utilized an entropy recombination strategy for thermodynamic equilibrium via compositional entropy exchange.
• Investigated the catalyst's performance in the reverse water gas shift reaction.

Main Results:

• Achieved an ultra-active thin rock salt shell HEO with superior mass activity (318 μmolCO gcat-1 s-1 at 380 °C).
• Demonstrated enhanced stability, outperforming Cu-based and noble metal catalysts.
• The core/shell architecture promoted a multicomponent surface, oxygen vacancy generation, and Cu exsolution, accelerating the redox pathway.

Conclusions:

• The entropy recombination strategy in HEOs is a breakthrough for catalyst design.
• The developed core/shell HEO catalyst shows significant promise for diverse catalytic applications, particularly RWGS.
• This approach effectively overcomes the activity-stability trade-off in HEO catalysis.