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

A microscopic understanding of how Fe-doping of Co(OH) improves electrocatalytic oxygen evolution remains elusive. We study two Co Fe (OH) 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 Fe (OH).

Identifying protons trapped in hematite photoanodes through structure-property analysis.

Uncertainty regarding the nature of structural defects in hematite and their specific impacts on material properties and photoelectrocatalytic water oxidation inhibits their development as photoanodes. We perform structure-property analysis on a series of hematite films fabricated by annealing lepidocrocite films with varied temperatures, annealing times and atmospheres and find a gradient in the magnitude of a crystal lattice distortion by tracking the relative intensity of a formally Raman inactive vibrational mode. Structure-property analysis reveals that this feature in the Raman spectrum correlates to photocurrent density, semiconductor band positions, and the onset of photoelectrocatalysis.