Directed Amorphous-to-Amorphous Reconstruction Toward Efficient Oxygen Evolution.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Unlocking the full catalytic potential of the oxygen evolution reaction (OER) requires guiding material reconstruction from amorphous to more potent amorphous structures.
• Developing effective electrocatalysts for OER is crucial for energy conversion technologies.

Purpose of the Study:

• To develop an amorphous cobalt coordination polymer (aCo) pre-catalyst that facilitates a controlled amorphous-to-amorphous transformation for enhanced OER.
• To investigate the mechanism by which this transformation activates lattice oxygen and improves catalytic performance.

Main Methods:

• Synthesis of an amorphous cobalt coordination polymer (aCo) pre-catalyst using monodentate end-capping.
• In-situ synchrotron radiation X-ray diffraction to study structural changes during catalysis.
• Computational analysis of energetic barriers for amorphous vs. crystalline phases.

Main Results:

• The amorphous structure redirects surface reconstruction to an amorphous cobalt oxyhydroxide (a-CoOOH) active layer with a lower energetic barrier.
• Amorphous-to-amorphous transformation activates lattice oxygen, switching OER pathways to a lattice oxygen-mediated mechanism.
• The optimized aCo catalyst achieved an overpotential of 186 mV at 10 mA cm⁻², outperforming RuO₂ and crystalline cobalt catalysts, with >100 h stability at 2 A cm⁻².

Conclusions:

• A directed surface-induced strategy using amorphous cobalt coordination polymers enables the design of highly efficient and stable OER electrocatalysts.
• The study provides fundamental insights into the relationship between lattice oxygen activity and structural disorder in OER catalysis.