Elucidating Two Distinct Pathways for Electrocatalytic Hydrogen Production Using Co^II Pincer Complexes

Area of Science:

• Inorganic Chemistry
• Sustainable Energy
• Electrochemistry

Background:

• Hydrogen gas is a key sustainable energy carrier.
• Efficient electrocatalytic hydrogen production is crucial for clean energy.
• Cobalt complexes show promise as electrocatalysts for hydrogen evolution.

Purpose of the Study:

• To investigate the electrocatalytic hydrogen generation of two cobalt(II) complexes.
• To explore the influence of different proton sources on catalytic activity.
• To elucidate the reaction mechanisms using electrochemical and computational methods.

Main Methods:

• Synthesis and characterization of two cobalt(II) complexes.
• Electrocatalytic hydrogen production studies using cyclic voltammetry and controlled potential coulometry.
• Density functional theory (DFT) calculations to analyze reaction pathways.

Main Results:

• Complexes I and II exhibited electrocatalytic activity for hydrogen production with various proton sources (TFA, AA, TFE).
• Electrocatalysis occurred at two distinct potentials, indicating different reduction processes.
• DFT analysis revealed two mechanistic pathways: M^I/M^III for stronger acids and M⁰/M^II for weaker proton sources.

Conclusions:

• The studied cobalt complexes effectively catalyze hydrogen evolution.
• Reaction pathways are dependent on the acidity of the proton source.
• Findings provide mechanistic insights for designing efficient electrocatalysts for sustainable hydrogen production.