High-Valence Metals Accelerate the Reaction Kinetics for Boosting Water Oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• High valence states in transition metals accelerate oxygen evolution reaction (OER) kinetics.
• Thermodynamic challenges often hinder the formation of these high-valence states in oxyhydroxides.

Purpose of the Study:

• To develop a novel strategy for achieving high-valence transition metals.
• To investigate the mechanism of modulating metal valence states for enhanced OER.
• To present a model catalyst demonstrating this strategy.

Main Methods:

• Constructing amorphous catalyst phases.
• Incorporating elements with Lewis acid or variable charge characteristics.
• Synthesizing and characterizing CeO2-NiFeOxHy as a model catalyst.

Main Results:

• CeO2-NiFeOxHy demonstrated modulated Ni valence states (Ni2+→Ni3+→Ni4+).
• The catalyst exhibited superior OER performance with low overpotentials (214 mV at 10 mA/cm², 659 mV at 500 mA/cm²).
• Exceptional stability was observed, outperforming control catalysts.

Conclusions:

• The proposed strategy effectively achieves high-valence active metals for efficient OER.
• Amorphous phase construction and element incorporation are key to modulating valence states.
• This approach offers a pathway to highly efficient electrocatalysts for energy applications.