High-spin transition metal atoms drive acidic oxygen evolution reactions

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Precious metal catalysts like IrO₂ and RuO₂ are expensive for the oxygen evolution reaction.
• Developing cost-effective, highly active, and stable transition metal catalysts remains a challenge.

Purpose of the Study:

• To create an efficient catalytic system using graphdiyne to enhance cobalt oxide performance for the acidic oxygen evolution reaction.
• To investigate the mechanism by which graphdiyne influences the electronic properties of cobalt oxide.

Main Methods:

• Synthesis of graphdiyne-induced high-spin state cobalt-based oxide (HSS-CoOₓ/GDY).
• Experimental characterization and theoretical calculations to understand the catalyst's electronic structure and reaction mechanism.
• Fabrication and testing of proton exchange membrane water electrolyzers using the developed catalyst.

Main Results:

• The HSS-CoOₓ/GDY catalyst demonstrated enhanced activity and stability for the acidic oxygen evolution reaction.
• Graphdiyne bonding induced a Jahn-Teller effect in CoO₆ octahedra, leading to high-spin Co³⁺ and optimized intermediate adsorption/desorption.
• Water electrolyzers achieved a current density of 1.0 A cm⁻² at 1.80 V.

Conclusions:

• Graphdiyne can effectively manipulate the electronic spin states of electrocatalysts.
• The HSS-CoOₓ/GDY system presents a promising alternative to precious metal catalysts for efficient water splitting.