Interplay between element-specific distortions and electrocatalytic oxygen evolution for cobalt-iron hydroxides.
Elif Pınar AlsaçMarlyn BokeJustine R BissonnetteRodney D L SmithPublished in: Chemical science (2024)
A microscopic understanding of how Fe-doping of Co(OH) 2 improves electrocatalytic oxygen evolution remains elusive. We study two Co 1- x Fe x (OH) 2 series that differ in fabrication protocol and find composition alone poorly correlates to catalyst performance. Structural descriptors extracted using X-ray diffraction, X-ray absorption spectroscopy, and Raman spectroscopy reveal element-specific distortions in Co 1- x Fe x (OH) 2 . These structural descriptors are composition-dependent within individual sample series but inconsistent across fabrication protocols, revealing fabrication-dependence in catalyst microstructure. Correlations between structural parameters from different techniques show that Fe-O resists bond length changes, forcing distortion of Co environments. We find the difference in O-M-O bond angles between Co and Fe sites to correlate with electrocatalytic behavior across both sample series, which we attribute to asymmetric distortion of potential energy surfaces for the Co(iii) to Co(iv) oxidation. A Tafel slope consistent with a rate-limiting step without electron transfer emerges as the O-Co-O angle decreases, implying a distortion-induced transition in the rate-limiting step. The fabrication dependence of electronic and bonding structure in the catalysts should be considered in theoretical and high-throughput analyses of electrocatalyst materials.
Keyphrases
- metal organic framework
- electron transfer
- high resolution
- raman spectroscopy
- high throughput
- reduced graphene oxide
- low cost
- tissue engineering
- randomized controlled trial
- single cell
- transition metal
- dual energy
- gene expression
- magnetic resonance imaging
- drug induced
- white matter
- magnetic resonance
- dna methylation
- diabetic rats
- multiple sclerosis
- oxidative stress
- escherichia coli
- staphylococcus aureus
- climate change
- room temperature
- iron deficiency