An intramolecular cobalt-peptoid complex as an efficient electrocatalyst for water oxidation at low overpotential

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science
• Renewable Energy

Background:

• Water electrolysis is a key method for producing hydrogen, a clean fuel.
• High overpotential and slow kinetics in water oxidation (WO) limit the efficiency of water splitting.
• Developing efficient, stable, non-precious metal electrocatalysts for WO remains a significant challenge.

Purpose of the Study:

• To design and synthesize a novel, bio-inspired molecular electrocatalyst for efficient water oxidation.
• To investigate the catalytic activity, stability, and mechanism of a cobalt(iii)-peptoid complex for homogeneous WO.
• To explore the role of a peptoid scaffold and its functional groups in enhancing catalytic performance.

Main Methods:

• Synthesis of a peptoid oligomer functionalized with terpyridine and bipyridine ligands and a proton-shuttling ethanolic group.
• Formation of an intramolecular cobalt(iii) complex with the peptoid ligand.
• Electrochemical characterization of the cobalt complex for water oxidation in aqueous phosphate buffer (pH 7).

Main Results:

• The Co(iii)-peptoid complex demonstrated efficient homogeneous water oxidation with high Faradaic efficiency (up to 92%).
• The catalyst operates at a low overpotential of approximately 430 mV, the lowest reported for Co-based homogeneous WO electrocatalysts.
• The complex exhibited high stability during electrocatalysis, with the ethanolic side chain crucial for activity, stability, and water binding.

Conclusions:

• A bio-inspired Co(iii)-peptoid complex serves as a highly efficient and stable molecular electrocatalyst for water oxidation.
• The designed peptoid scaffold effectively mimics enzymatic second coordination spheres, enhancing catalytic performance.
• This work presents a promising strategy for developing advanced electrocatalysts for clean hydrogen production via water splitting.