Electrochemical Reduction Pathways from Goethite to Green Iron in Alkaline Solution with Silicate Additive

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Manufacturing

Background:

• Iron electrolysis offers a sustainable, zero-carbon pathway for iron production using renewable energy.
• Current methods face challenges with inefficient reduction of iron oxides (Fe3O4) and hydrogen gas evolution.

Purpose of the Study:

• To investigate the use of silicate additives in alkaline electrolytes for efficient electrochemical reduction of goethite (FeOOH).
• To mitigate the accumulation of electrochemically inert Fe3O4 and suppress parasitic H2 generation during iron electrolysis.

Main Methods:

• Electrochemical measurements were employed to analyze the reduction process.
• Operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were used to study reaction pathways.
• Atomistic simulations were utilized to understand the role of silicate.

Main Results:

• The addition of silicate to a sodium hydroxide electrolyte facilitated the electrochemical reduction of goethite (FeOOH).
• A poorly crystalline iron hydroxide (Fe-(OH)2) phase formed, improving the subsequent reduction of Fe3O4.
• Silicate addition effectively reduced parasitic H2 generation, enhancing overall energy efficiency.

Conclusions:

• Silicate acts as a cost-effective electrolyte additive to enhance room-temperature green iron production via electrolysis.
• The findings demonstrate a promising strategy to overcome key limitations in electrochemical ironmaking.