Electrocatalytic water oxidation with bioinspired cubane-type Co^II complexes

Area of Science:

• Coordination Chemistry
• Materials Science
• Electrochemistry

Background:

• Development of efficient and stable catalysts for water oxidation is crucial for renewable energy technologies.
• Cubane-type metal complexes offer unique structural and electronic properties for catalytic applications.
• Cobalt complexes are actively investigated as cost-effective alternatives to precious metal catalysts.

Purpose of the Study:

• To synthesize and characterize novel cubane-type cobalt complexes with benzimidazole-based ligands.
• To evaluate the electrocatalytic activity of these complexes for water oxidation.
• To investigate the structural, magnetic, and stability properties of the synthesized complexes.

Main Methods:

• Self-assembly synthesis of cubane-type cobalt complexes [(μ³-L¹O)CoCl(MeOH)]₄ (1) and [(μ³-L²O)CoCl(MeOH)]₄ (2).
• Characterization using magnetic studies, DFT analyses, and ac-susceptibility measurements.
• Electrocatalytic water oxidation studies using cyclic voltammetry and Electrochemical Quartz Microbalance (EQCM).

Main Results:

• Complexes 1 and 2 were synthesized in high yields with cubane-type {Co₄O₄} cores.
• Complex 1 exhibited antiferromagnetic behavior, while complex 2 showed ferromagnetic coupling and single molecular magnet behavior.
• Both complexes catalyzed water oxidation, with complex 2 showing higher turnover frequency (1.99 s^-1) and better stability.

Conclusions:

• The synthesized cubane-type cobalt complexes are effective electrocatalysts for water oxidation.
• Complex 2 demonstrates enhanced catalytic performance and superior stability compared to complex 1.
• These findings contribute to the development of robust and efficient molecular catalysts for water splitting.