Electrocatalytic water oxidation by a monomeric amidate-ligated Fe(III)-aqua complex

Area of Science:

• Inorganic Chemistry
• Electrocatalysis
• Sustainable Energy

Background:

• Water oxidation is a critical process for renewable energy technologies.
• Developing efficient and stable electrocatalysts is essential for practical applications.
• Iron complexes offer a cost-effective alternative to precious metal catalysts.

Purpose of the Study:

• To investigate the electrocatalytic activity of a six-coordinate Fe(III)-aqua complex, [Fe(III)(dpaq)(H2O)](2+), for water oxidation.
• To elucidate the mechanism of water oxidation catalyzed by the iron complex.
• To assess the long-term stability and efficiency of the catalyst under operational conditions.

Main Methods:

• Electrochemical kinetics study using cyclic voltammetry and chronoamperometry.
• Synthesis and characterization of the iron complex [Fe(III)(dpaq)(H2O)](2+).
• Electrolysis experiments using a high surface area electrode in propylene carbonate-water mixtures.

Main Results:

• The iron complex acts as an efficient electrocatalyst for water oxidation.
• Water oxidation proceeds via a single-site mechanism involving Fe(V)(O)(2+).
• Sustained catalysis with over 29 turnovers, 45% Faradaic yield, and no catalyst decomposition over 15 hours was achieved.

Conclusions:

• The developed iron complex is a stable and effective electrocatalyst for water oxidation.
• The findings support the use of earth-abundant metal complexes in sustainable energy applications.
• The single-site mechanism provides valuable insights for designing future water oxidation catalysts.