Electrocatalytic CO₂ Reduction with a Binuclear Bis-Terpyridine Pyrazole-Bridged Cobalt Complex

Area of Science:

• Inorganic Chemistry
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for carbon dioxide (CO2) reduction is crucial for sustainable energy solutions.
• Cobalt complexes are promising candidates for CO2 electroreduction due to their redox properties.

Purpose of the Study:

• To synthesize and characterize a novel dinuclear cobalt complex with pyrazole-terpyridine ligands.
• To investigate the electrocatalytic activity of the synthesized complex for CO2 reduction to CO.
• To elucidate the mechanism and factors influencing the selectivity and efficiency of the electrocatalytic process.

Main Methods:

• Synthesis of a pyrazole-based ligand and its dinuclear cobalt complex.
• Electrochemical techniques including cyclic voltammetry and spectro-electrochemical studies (UV-vis, IR).
• Electrocatalytic reduction of CO2 in the presence of Brønsted acids and varying concentrations of trifluoroethanol (TFE).

Main Results:

• The dinuclear cobalt complex exhibits pairwise reduction processes.
• Spectro-electrochemical studies confirm the formation of a CO-containing dicobalt complex during CO2 electroreduction.
• High selectivity (up to 94%) for CO formation was achieved in the presence of 1.47 M TFE at -1.35 V vs. SCE.
• Low faradaic efficiencies (<50%) were attributed to the inhibitory effect of CO-containing intermediates.

Conclusions:

• The synthesized dinuclear cobalt complex is an effective electrocatalyst for CO2 reduction to CO.
• The presence of Brønsted acids and TFE influences the catalytic mechanism and selectivity.
• Further optimization is needed to overcome the limitations imposed by intermediate species and improve overall efficiency.