Illustration of dendritic iron growth fed by dissolved ferrous intermediates. This metallic iron tree propagates by providing numerous electron transfer pathways to the reduced products of hematite dissolution. The diffraction pattern represents a partially reacted surface phase detected by TEM. Understanding and controlling these dissolved intermediates is crucial for electrochemical ironmaking and the design of iron–air batteries. Portions of this illustration were created with the assistance of generative AI tools in Adobe Illustrator. View the article.

PhD/Postdoc Openings Update: 12/09/2025 There is one fully-funded PhD opening in the group in the area of microstructure control during vat photopolymerization or on the fundamentals of crosslinking. ...

Start-up firms have pilot plants for making steel with low carbon emissions, but can they scale up?

Electrochemical ironmaking can provide an energy efficient, zero-emissions alternative to traditional methods of ironmaking, but the scalability of low-temperature electrochemical cells may be constrained by reactor throughput and the availability of acceptable feedstocks. Electrodes directly converting solid iron-oxide particles to metal circumvent traditional mass-transport limitations but are sensitive to both the particle size and nanoscale morphology of reactants. The effect of these properties on reactor throughput has not been systematically studied at model electrowinning surfaces. Here, we have used size-controlled, homologous α-Fe2O3 particles to study how the nanoscale morphology of oxides influences the obtainable current density toward Fe metal and integrated these results in a technoeconomic model for alkaline iron electrowinning systems. Micron-scale α-Fe2O3 with nanoscale porosity can be used to form Fe at current densities commensurate with industrial water electrolysis (>0.6 A cm–2) in the absence of external convection, providing a path to cost-competitive and scalable ironmaking using electrochemistry.

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Dissolved iron (Fe) species are prerequisites for the most active catalyst sites for the oxygen evolution reaction in alkaline electrolytes, but the overall effects of dissolved Fe on energy-efficient advanced alkaline water electrolysis cells remain unclear. Here, we systematically control the concentration of Fe in a model zero-gap alkaline water electrolyzer to understand the interactions between Fe and high surface area catalyst coatings. Cells employing a platinum-group-metal-containing cathode and a high surface area, mixed-metal-oxide anode yielded an optimum voltage efficiency at elevated temperatures and in the presence of 6 ppm Fe, which reduced the cell voltage by ∼100 mV compared to rigorously Fe-free electrolytes. Increasing concentrations of Fe led to a systematic increase in anode activity toward the oxygen evolution reaction and a reduction in the electrochemically active surface area at both the anode and cathode. Metallic Fe was not observed to electrodeposit at cathodes which operate at overpotentials ≤120 mV, but dissolved Fe does reduce the apparent number density of sites available for hydride adsorption. These findings suggest that the energy efficiency of advanced alkaline water electrolysis systems can be improved by managing the Fe concentration in recirculating KOH electrolytes.

The corrosion kinetics of metals in the presence of polymer electrolytes─which are frequently used in devices for the electrochemical production of hydrogen, hydrocarbons, and alcohols─is convoluted b...