Understanding electrochemical switchability of perovskite-type exsolution catalysts

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Exsolution of metal nanoparticles from perovskite oxides yields catalysts with enhanced properties.
• Exsolution catalysts offer tunable activity states via electrochemical switching.

Purpose of the Study:

• To investigate the electrochemical switching mechanism of exsolution catalysts.
• To correlate phase changes of exsolved particles with catalytic activity.
• To understand the role of metallic particles in H2 oxidation and H2O splitting.

Main Methods:

• Synchrotron-based in-situ X-ray diffraction on electrochemically polarized La0.6Sr0.4FeO3-δ thin film electrodes.
• Simultaneous monitoring of phase composition and catalytic activity.

Main Results:

• Reversible electrochemical switching between high and low activity states was observed.
• Switching is accompanied by phase transformation of exsolved iron particles between metallic α-Fe and Fe-oxides.
• Metallic particles influence H2 oxidation and H2O splitting mechanisms, with particle size being a minor factor.

Conclusions:

• Electrochemical switching of catalyst activity is achievable through reversible phase changes of exsolved iron nanoparticles.
• This process is suitable for intermediate temperature applications without requiring iron reintegration into the perovskite lattice.
• The study elucidates the catalytic mechanisms of exsolved metallic particles in H2 oxidation and H2O splitting.