Chemists are pioneering a clean electrochemical method of making iron, a key step in decarbonizing the steel industry. Their process uses brine and iron oxide, replacing a blast furnace with a higher carbon content, and is optimized to use natural materials. By finding iron oxides that are low-cost, porous and significantly more efficient, the team is laying the foundation for large-scale, environmentally friendly steel production. With the help of engineers and manufacturers, they are pushing this green technology closer to the real world.

Chemists at the University of Oregon are working to find a cleaner way to produce iron for use in steelmaking, one of the world's largest carbon emitters.

Last year, University of Oregon chemist Paul Kempler and his team introduced a method to make iron using electrochemistry. The process relies on a series of chemical reactions that convert brine and iron oxide into pure iron metal.

In their latest study, the researchers focused on improving the process by determining which types of iron oxides could make the reaction more cost-effective, an important step toward scaling up the method for industrial use.

"We actually have a chemical principle, a guiding design rule, that will teach us how to identify low-cost iron oxides that can be used in these reactors," Kempler said.

The research was published April 9 in ACS Energy Letters.

In 2024, global steel production will approach 2 billion tons, used in everything from construction to automobiles to infrastructure. Currently, the most fossil fuel-intensive step in the steel production process is the conversion of iron ore (iron oxide found in nature) into pure iron metal.

Traditionally, iron is made in blast furnaces, which emit carbon dioxide into the atmosphere, but Kempler's team is developing a different method of making iron.

Postdoc Ana Konovalova shows off an electrochemical cell designed in Paul Kempler's lab. Image source: University of Oregon

Their process uses cheap and readily available brine and iron oxide as raw materials, converting them into iron metal through a series of chemical reactions. These reactions also produce chlorine, a commercially valuable by-product.

When Kempler and his team began developing their process several years ago, they obtained small amounts of iron oxide from chemical supply companies.

These materials performed well in laboratory tests, but they did not reflect the iron-rich materials found in nature, which have greater differences in composition and structure.

"Then the natural next question is: What would happen if you actually tried to process something that was dug directly out of the ground, without additional purification, grinding, etc.?" said Ana Konovalova, a postdoctoral researcher in Kempler's lab who co-led the project.

When the team tried different kinds of iron oxides, it became clear that some worked much better than others. But the researchers aren't sure what caused the difference in the amount of iron metal they produced from the different starting materials. What is the size of the iron oxide particles? Or the composition of the material? Or the presence or absence of specific impurities?

The shape and porosity of metal oxide particles, rather than particle size, are critical to the efficiency of electrochemical ironmaking. Image source: Adapted from ACS Energy Letters 2025, DOI: 10.1021/acsenergylett.5c00166

Konovalova and graduate student Andrew Goldman found creative ways to test certain variables while holding others constant.

For example, they made iron oxide powder into nanoparticles and heat-treated some of the nanoparticles to make them denser and less porous.

"It solidified into the same secondary nanoparticle shape, but no more primary particles were observed inside. It was essentially the same material, just in a different stage," Konovalova said.

In laboratory tests, the difference was dramatic: "With these porous particles, we can make iron very quickly in a small area," Goldman said, "whereas dense particles can't achieve the same speed, so we're limited in the amount of iron we can make per square meter of electrode."

This was a key insight in making the process work on an industrial scale, the success of which often depends on economic factors.

Large electrochemical plants are expensive to build, and the cost is directly proportional to the electrode area. To make it economically viable, the electrode needs to be able to generate enough product quickly to recoup the initial investment. The faster reaction rate of porous particles means the initial capital cost can be recouped more quickly, thus reducing the final cost of the iron product, ideally low enough to compete with traditional methods.

The key point, Kempler says, is not that these specific nanoparticles are essential for the electrochemical process to work well. Instead, this study shows that the surface area of ​​the starting material is what really matters. Porous nanoparticles have a larger surface area, which is conducive to the reaction and thus speeds up the reaction. Other iron oxides with porous structures may also be cost-effective.

“The goal is to find a resource that is abundant, cheap, and has a low environmental impact,” Kempler said. "We would not be satisfied if we invented a method that was more destructive than the current dominant method of making iron."

To take their process beyond the lab, Kempler's lab is collaborating with researchers in other fields. Working with OSU civil engineers helped them better understand the conditions required for the product to be used in real-world applications. Partnering with an electrode manufacturing company helped them solve the logistical and scientific challenges of scaling up the electrochemical process.

Compiled from /ScitechDaily