Spin State Differentiated [3Fe-4S] Cluster Electrocatalyzes Water Oxidation Efficiently

Area of Science:

• Bioinorganic Chemistry
• Electrocatalysis
• Materials Science

Background:

• Synthetic iron-sulfur clusters mimic natural metalloenzymes but their spin state's catalytic influence is understudied.
• Developing efficient and cost-effective catalysts for water oxidation is crucial for sustainable energy technologies.

Purpose of the Study:

• To investigate the catalytic activity of a novel disulfide-bridged triiron(II) complex for electrocatalytic water oxidation.
• To elucidate the role of the spin state and coordination environment of iron sites in catalytic performance.

Main Methods:

• Synthesis and characterization of a disulfide-bridged triiron(II) complex, [Fe3(Sip)4][CF3SO3]2.
• Electrochemical evaluation of the complex for water oxidation catalysis.
• Analysis of the coordination environment and spin state of iron centers.

Main Results:

• The iron-sulfur complex ([Fe3(Sip)4]) demonstrated efficient electrocatalytic water oxidation with a turnover frequency of 932 s⁻¹ and Faraday efficiency of 86%.
• Terminal low-spin (S=0) iron(II) sites with a N4S2 coordination environment were identified as crucial for the high catalytic activity.
• Ligand synergy further contributed to the overall catalytic efficiency.

Conclusions:

• The study highlights the significant role of spin state in iron-sulfur cluster catalysis for water oxidation.
• This research presents an unconventional application of iron-sulfur clusters and suggests a promising direction for designing advanced electrocatalysts.