The Restructuring-Induced CoO Catalyst for Electrochemical Water Splitting.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Transition metal sulfides can restructure during electrochemical reactions, leading to enhanced catalytic activity.
• Understanding the in situ generated structures is crucial for establishing structure-property relationships in catalysis.
• Oxygen evolution reaction (OER) is vital for hydrogen generation via water-splitting.

Purpose of the Study:

• To investigate the restructuring process of cobalt sulfide (Co9S8) during the oxygen evolution reaction (OER).
• To identify the in situ generated active sites responsible for high catalytic performance.
• To establish the structure-property relationship for these dynamically evolving catalysts.

Main Methods:

• Multimodel operando characterizations: Raman spectroscopy, X-ray absorption spectroscopy, and X-ray reflectivity.
• Investigation of cobalt sulfide (Co9S8) restructuring during electrochemical OER.
• Density functional theory (DFT) calculations to verify active site structures.

Main Results:

• Co9S8 restructures into oxide clusters (CoO) with six oxygen-coordinated cobalt octahedra (CoO6) as the fundamental unit.
• These in situ generated oxide clusters exhibit significantly higher OER activity than commercial standards like RuO2.
• DFT calculations confirm that edge-sharing CoO6 octahedral clusters are the true active sites for OER.

Conclusions:

• The study elucidates the restructuring mechanism of Co9S8, identifying specific oxide clusters as highly active OER catalysts.
• The findings provide critical insights into designing novel transition-metal-based electrocatalysts that undergo restructuring.
• This work advances the understanding of in situ catalyst evolution for efficient electrochemical energy conversion.