Interplay between element-specific distortions and electrocatalytic oxygen evolution for cobalt-iron hydroxides.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Understanding Fe-doping effects on Co(OH)2 for oxygen evolution reaction (OER) catalysis is crucial.
• Existing knowledge lacks microscopic insights into how Fe incorporation influences OER performance.

Purpose of the Study:

• To elucidate the relationship between Fe-doping, microstructure, and electrocatalytic activity in Co(OH)2.
• To identify key structural descriptors correlating with OER performance.

Main Methods:

• Synthesis of two Co1-xFex(OH)2 series with varying fabrication protocols.
• Characterization using X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and Raman spectroscopy.
• Correlation analysis between structural parameters and electrocatalytic OER performance.

Main Results:

• Catalyst performance showed poor correlation with composition alone.
• Element-specific distortions in Co1-xFex(OH)2 were observed, dependent on fabrication.
• Fe-O bonds resisted distortion, inducing changes in Co environments and O-M-O bond angles.
• O-M-O bond angle differences correlated with OER activity, suggesting distorted potential energy surfaces.
• Decreasing O-Co-O angles indicated a transition in the rate-limiting step.

Conclusions:

• Fabrication protocols significantly impact the microstructure and electronic structure of Fe-doped Co(OH)2.
• Microstructural distortions, particularly O-M-O bond angles, are key determinants of OER performance.
• Future theoretical and high-throughput studies must account for fabrication-dependent effects in electrocatalyst design.