Strained-Induced Morphological Reconstruction of RuO₂(110) Thin-Film Electrocatalysts

Area of Science:

• Materials Science
• Surface Science
• Electrochemistry

Background:

• Strain engineering is crucial for optimizing electrocatalyst performance.
• Excessive strain can induce detrimental materials transformations, impacting catalyst stability and function.
• Understanding strain relaxation mechanisms is vital for designing robust electrocatalysts.

Purpose of the Study:

• To investigate the effect of strain on the surface morphology of rutile ruthenium dioxide (RuO2) films.
• To identify strain relaxation pathways in RuO2 films grown on rutile titanium dioxide (TiO2) substrates.
• To determine if strain relaxation impacts ruthenium dissolution during electrochemical processes.

Main Methods:

• Growing rutile RuO2 films on rutile TiO2(110) substrates.
• Utilizing in situ atomic force microscopy (AFM) to observe surface morphology during electrochemistry.
• Employing density functional theory (DFT) calculations to assess surface energies.
• Conducting inductively coupled plasma-mass spectrometry (ICP-MS) to quantify ruthenium dissolution.

Main Results:

• RuO2 films thicker than 9 nm relax strain by forming step edges exposing the {011} plane.
• DFT calculations confirm that the (011) facet has a low surface energy for rutile RuO2.
• AFM demonstrated that the RuO2(110) terrace structure remains stable during electrochemical operation.
• ICP-MS analysis showed that ruthenium dissolution is not significantly affected by strain.

Conclusions:

• Rutile RuO2(110) films exhibit a strain-relieving surface reconstruction mechanism involving {011} facet exposure.
• This reconstruction pathway effectively mitigates strain without compromising the material's stability against dissolution.
• The findings offer a model for strain management in electrocatalysts that preserves material integrity.