Tuning the ligand periphery in homoleptic Co(III) complexes: a versatile strategy to modulate electrocatalytic oxygen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient, cost-effective, and Earth-abundant molecular electrocatalysts is critical for sustainable energy solutions.
• Cobalt complexes are promising candidates for catalyzing key reactions like the oxygen evolution reaction (OER).

Purpose of the Study:

• To design and synthesize novel mononuclear Cobalt(III) complexes.
• To investigate the electrocatalytic activity of these complexes for the oxygen evolution reaction (OER).
• To understand the structure-activity relationship influenced by ligand electronic modifications.

Main Methods:

• Synthesis of four new mononuclear Co(III) complexes using Schiff base ligands.
• Characterization using single-crystal X-ray diffraction (SCXRD).
• Electrochemical evaluation of OER activity in 1 M KOH solution, including overpotential and Tafel slope measurements.
• Post-operational stability studies using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).

Main Results:

• Four homoleptic mononuclear anionic Co(III) complexes were successfully synthesized and structurally characterized.
• All synthesized complexes exhibited promising electrocatalytic activity for OER.
• Complex C4, featuring a specific ligand combination, showed superior performance with a low overpotential (340 mV at 10 mA cm⁻²) and a low Tafel slope (63 mV dec⁻¹).
• Post-operational studies confirmed the structural and morphological stability of complex C4.

Conclusions:

• The synthesized Co(III) complexes are effective molecular electrocatalysts for OER.
• Complex C4 demonstrates outstanding catalytic efficiency attributed to synergistic electronic effects from ligand substituents.
• Electronic modifications on the ligand framework significantly influence the catalytic performance of homoleptic Co(III) complexes in OER.
• This study provides insights into designing efficient molecular electrocatalysts for sustainable energy applications.