One-Step High-Temperature Electrodeposition of Fe-Based Films as Efficient Water Oxidation Catalysts

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient water electrolysis for hydrogen production requires advanced catalysts.
• Iron-based catalysts are desirable due to their low cost and abundance.
• Current methods for iron oxide electrodeposition often require controlled atmospheres and post-deposition treatments.

Purpose of the Study:

• To develop a simplified, single-step electrodeposition method for iron-based catalysts.
• To investigate the effect of deposition temperature on iron oxide film structure and properties.
• To evaluate the electrocatalytic performance of the deposited films for the oxygen evolution reaction.

Main Methods:

• Electrochemical deposition of iron oxide films using ferrocene and propylene carbonate at varying temperatures (298 K and 313 K).
• Structural characterization using X-ray diffraction (XRD).
• Spectroscopic analysis including X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), and electron paramagnetic resonance (EPR).
• Electrochemical performance evaluation via water oxidation tests, turnover frequency measurements, and electrochemical impedance spectroscopy (EIS).

Main Results:

• A single-step electrodeposition method was established, eliminating the need for controlled atmospheres.
• Crystalline hematite films were formed at 313 K, while amorphous films formed at 298 K.
• Films deposited at 313 K exhibited significantly enhanced electrocatalytic activity for water oxidation (turnover frequency of 0.028 s⁻¹), 4.5 times higher than those at 298 K.
• The 313 K-deposited films showed a 100 mV lower overpotential and the least charge transfer resistance, indicating efficient electron transport.

Conclusions:

• This work presents the first report of electrodeposited crystalline iron-based films for alkaline oxygen evolution reaction without post-deposition treatment.
• The developed method offers a facile and efficient route to produce high-performance electrocatalysts for water splitting.
• Optimizing deposition temperature is critical for achieving superior catalytic properties in iron oxide films.