Bis(formazanate) iron(II) complexes as cathode materials for one-compartment H₂O₂ fuel cells

Area of Science:

• Coordination Chemistry
• Materials Science
• Electrochemistry

Background:

• Development of novel redox-active ligands is crucial for advanced materials.
• Iron(II) complexes offer tunable electronic properties for catalytic applications.
• Hydrogen peroxide fuel cells require efficient cathode materials for energy conversion.

Purpose of the Study:

• Synthesize and characterize novel bis(formazanate) iron(II) complexes.
• Investigate the electrochemical properties of these new complexes.
• Evaluate their performance as cathode materials in hydrogen peroxide fuel cells.

Main Methods:

• Synthesis of benzothiazole-substituted formazanate ligands and their iron(II) complexes.
• Structural characterization using single-crystal X-ray diffraction (XRD).
• Electrochemical studies including cyclic voltammetry.
• Fabrication and testing of one-compartment membrane-less H2O2 fuel cells.

Main Results:

• Two six-coordinate, pseudo-octahedral bis(formazanate) Fe(II) complexes, [Fe(L1)2] and [Fe(L2)2], were successfully synthesized.
• Structural elucidation confirmed the molecular structures of the complexes.
• Cyclic voltammetry revealed the ability of the complexes to form anionic and dianionic species upon reduction.
• The complexes demonstrated potential as cathodes in H2O2 fuel cells, achieving maximum power densities of 1.88 mW cm-2 and 3.08 mW cm-2.

Conclusions:

• The synthesized formazanate-based iron(II) complexes exhibit promising electrochemical activity.
• These complexes can function effectively as cathode materials in hydrogen peroxide fuel cells.
• The study highlights the potential of formazanate chemistry in developing advanced energy conversion materials.