Nickel Oxide Catalysts Could Speed Up Hydrogen-Based Green Steelmaking

Hydrogen-based steelmaking is one of the most promising routes toward low-carbon steel production. Instead of using carbon to remove oxygen from iron ore, hydrogen can be used as the reducing agent, producing water rather than carbon dioxide.

But while the concept is attractive, one of the major technical challenges is speed. Hydrogen-based reduction of iron oxide can be relatively slow, especially at lower temperatures. That makes the process harder to scale economically and energy-efficiently.

Recent research from the Max Planck Institute for Sustainable Materials suggests a possible way forward: using nickel oxide as a catalytic precursor to accelerate the hydrogen reduction of iron oxide.

Why Hydrogen-Based Steelmaking Matters

Conventional steel and metal production is responsible for a significant share of global carbon dioxide emissions. Much of this comes from the use of carbon, both as a fuel and as a chemical reducing agent.

In traditional ironmaking, carbon helps strip oxygen from iron ore. The result is iron, but also large amounts of CO₂.

Hydrogen-based production changes the chemistry. Hydrogen reacts with oxygen in the ore to form water. In simplified terms:

iron oxide + hydrogen → iron + water

This makes hydrogen-based steelmaking a major pathway for producing green steel, provided the hydrogen itself is produced using low-carbon or renewable energy.

The Main Challenge: Reaction Speed

Turning iron oxide into metallic iron is not instant. Hydrogen must reach the iron oxide, react with it, remove oxygen, and allow the resulting water vapour to escape.

At industrial scale, this reaction speed matters enormously. A slower process means longer production times, higher energy demand, and potentially higher cost.

According to the Max Planck research, one of the obstacles to wider adoption is the relatively slow reduction of metal ores at temperatures below 800°C.

How Nickel Oxide Helps

The researchers found that adding nickel oxide can make the hydrogen-based reduction process significantly faster.

Nickel oxide acts as what scientists call a catalytic precursor. This means it is not simply added as an inert ingredient. During the hydrogen reduction process, the nickel oxide is itself reduced and transformed into a highly porous nickel structure.

This nanoporous nickel then acts as a catalyst, helping hydrogen reduce iron oxide more efficiently.

In practical terms, the researchers reported two important effects:

The reduction process became approximately twice as fast.
The reaction began at a temperature around 100°C lower than without the nickel oxide.

Both results are important. A faster reaction can increase productivity, while a lower reaction temperature can reduce energy requirements.

A Simple Way to Understand the Mechanism

Iron oxide reduction is like trying to remove oxygen from a dense solid material. Hydrogen gas needs access to the reactive surfaces where oxygen can be removed.

When nickel oxide is added, hydrogen first converts it into nanoporous nickel. This nickel has a sponge-like structure at the nanoscale, with many tiny internal surfaces.

Those surfaces help the hydrogen reaction proceed more easily. Nickel is also good at interacting with hydrogen, which makes it useful in helping hydrogen participate in the reduction process.

So the nickel does not simply “sit there.” It helps create more effective reaction sites and improves the pathway by which oxygen is removed from iron oxide and converted into water.

Why Nickel Is a Practical Choice

Nickel is not foreign to steelmaking. It is already an important alloying element in many high-value steels, including stainless steels such as grades 304 and 316.

Nickel is also used in high-strength steels, cryogenic steels, automotive applications, energy systems, and medical-related alloys.

That makes this approach especially interesting. In some processes, catalysts must be separated from the final product. Here, the nickel can potentially remain as part of the final alloy, where it may add useful properties.

In other words, nickel oxide may serve two roles:

helping the hydrogen reduction process move faster,
and contributing nickel to the final steel alloy.

Why This Research Is Important for Green Steel

The study points to a new way of improving hydrogen-based steel production: not only by changing the fuel or the furnace, but by improving the chemistry inside the reduction process itself.

If catalytic additives can make hydrogen reduction faster and more energy-efficient, they could help address one of the major barriers to commercial green steel production.

This could be particularly relevant for nickel-containing steels, where the catalyst also becomes a useful alloying element.

What Still Needs to Happen

This is an important scientific development, but it does not mean full industrial adoption is immediate.

For hydrogen-based steelmaking to compete at scale, several questions still need to be addressed:

Can the process be scaled reliably from laboratory conditions to industrial production?
What are the economics of using nickel oxide in different steel grades?

How much energy can be saved in real-world operations?
Is there sufficient supply of affordable green hydrogen?
Can similar catalytic effects be achieved with other alloying elements, such as cobalt or other transition metals?

The researchers themselves note that industrial implementation will require further technological and economic development.

The World of Steel Takeaway

Nickel oxide may become an important enabler for hydrogen-based green steelmaking, especially for nickel-containing steels such as stainless grades 304 and 316.

By transforming into nanoporous nickel during hydrogen reduction, it helps hydrogen remove oxygen from iron oxide more quickly and at lower temperatures. That could improve productivity and reduce energy demand, two key factors for making green steel commercially viable.

The broader lesson is that green steel will not be achieved through hydrogen alone. It will also require smarter process chemistry, effective catalysts, and alloy designs that make low-carbon production faster, cleaner, and economically realistic.