Designing water resistant high entropy oxide materials.

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Moisture negatively impacts industrial catalyst performance.
• Developing water-resistant catalysts is crucial for process efficiency.

Purpose of the Study:

• Propose a concept for designing water-resistant oxide catalysts by engineering entropy.
• Investigate the effect of configurational entropy on catalyst stability and performance in the presence of water.

Main Methods:

• Density Functional Theory (DFT) calculations to assess adsorption and dissociation energies.
• Experimental synthesis and testing of spinel catalysts (ACr2O4, A=Ni, Mg, Cu, Zn, Co).
• Characterization using H2O-Temperature Programmed Desorption (TPD), in-situ Raman, and in-situ Fourier-Transform Infrared Spectroscopy (FTIR).

Main Results:

• Higher configurational entropy in catalysts correlates with improved C3H6 adsorption, water dissociation, and oxygen vacancy formation.
• A high entropy oxide catalyst ((Ni0.2Mg0.2Cu0.2Zn0.2Co0.2)Cr2O4) demonstrated excellent water resistance (>100 h) in C3H6 oxidation.
• Binary oxide catalysts showed significantly lower water resistance, deactivating within 20 h.

Conclusions:

• Engineering configurational entropy is an effective strategy for designing water-resistant oxide catalysts.
• High entropy oxides exhibit enhanced hydrothermal stability due to lower Gibbs free energy.
• This approach provides a pathway for developing robust catalysts for challenging industrial environments.