Unveiling the Electrolyte Cations Dependent Kinetics on CoOOH-Catalyzed Oxygen Evolution Reaction

Area of Science:

• Electrocatalysis
• Materials Science
• Surface Chemistry

Background:

• Electrolyte cation effects on electrocatalysis kinetics are widely observed but mechanistically debated.
• Understanding cation influence is crucial for optimizing electrocatalytic processes like the oxygen evolution reaction (OER).

Purpose of the Study:

• To elucidate the mechanism by which electrolyte cations influence cobalt oxyhydroxide (CoOOH) catalyst performance during OER.
• To investigate the correlation between cation size, catalyst structure, and OER activity.

Main Methods:

• Operando X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) to observe structural changes.
• X-ray absorption spectroscopy (XAS), in situ Raman, in situ UV/Vis spectroscopy, cyclic voltammetry (CV), and theoretical calculations to probe electronic structure and reaction intermediates.

Main Results:

• Electrolyte cations (Cs+, K+, Na+, Li+) intercalate into CoOOH layers, with larger cations causing greater interlayer expansion and enhanced OER activity.
• Cation intercalation modifies cobalt oxidation states and Co-O bond lengths, optimizing the d-band center and oxygen intermediate adsorption.
• This process facilitates the formation of active Co(IV) species and lowers the energy barrier for the rate-determining step in OER.

Conclusions:

• The study provides a detailed mechanism for electrolyte cation-dependent OER kinetics in CoOOH catalysts.
• Intercalation of larger cations enhances OER activity by structurally and electronically modifying the catalyst.
• Findings offer insights into cation-targeted electrocatalysis mechanisms beyond OER.