Why Green Hydrogen Electrolyzers
Use Nickel Foam Electrodes

The Green Hydrogen Buildout Has a Materials Problem

Water electrolysis — splitting water into hydrogen and oxygen using electricity — is the core reaction behind every green hydrogen project now under construction, from Saudi Arabia's 2.2 GW NEOM complex to the multi-gigawatt alkaline electrolyzer lines commissioning across Germany, the Netherlands, China, and South Korea. Scaling electrolysis from lab bench to gigawatt-scale industrial infrastructure is not just an electrical engineering problem. It is a materials sourcing problem, and nickel foam sits near the center of it.

Every electrolyzer stack needs an electrode substrate that can hold catalyst material, conduct current with minimal loss, survive a highly corrosive electrolyte for a multi-year service life, and let hydrogen and oxygen gas bubbles escape without disrupting the reaction. Very few materials satisfy all four requirements at a cost that scales to gigawatt production. Nickel foam is the material the alkaline electrolysis industry has converged on.

The Four Properties Electrolyzer Electrodes Actually Need

Alkaline water electrolyzers run at high current densities inside a bath of concentrated potassium hydroxide (KOH) electrolyte, typically operating for a decade or more without electrode replacement. That combination of conditions rules out most low-cost conductive materials quickly:

• High surface area for catalyst loading. Nickel foam's open, three-dimensional cellular structure provides dramatically more surface area per unit volume than a flat plate or mesh electrode, which means more catalytic reaction sites for the same stack footprint — directly improving current density and reducing the size (and cost) of the stack needed for a given hydrogen output.
• Metallic electrical conductivity. As a solid nickel structure rather than a coated or composite material, the foam conducts current with minimal resistive loss through the electrode itself, which matters at the current densities modern alkaline stacks are designed to run at.
• Corrosion resistance in KOH electrolyte. Nickel is one of the few economical metals that remains chemically stable in concentrated alkaline solution over years of continuous operation — the same property, incidentally, that makes it useful in nickel-metal-hydride batteries, which also use alkaline electrolyte.
• Efficient gas bubble release. Electrolysis generates hydrogen and oxygen gas continuously at the electrode surface. If bubbles cling to the electrode instead of escaping, they physically block active reaction sites and increase cell voltage — wasted energy that shows up directly on the electricity bill for every kilogram of hydrogen produced. Foam's interconnected open-pore geometry is significantly better at releasing bubbles than a flat or lightly perforated electrode.

Specifying Electrolyzer-Grade Nickel Foam: Pore Size Is the Key Trade-Off

Not all nickel foam is interchangeable across applications. The pore size that makes sense for an air filter is not the pore size that makes sense for an electrolyzer electrode, and this is where a materials supplier's application experience matters more than the headline "nickel foam" spec.

Filtration-grade nickel foam — the kind used in server dust filters or HVAC applications — is typically specified in the 10–30 PPI (pores per linear inch) range, prioritizing airflow and particle capture geometry. Electrolyzer electrode substrates run considerably finer, commonly in the 60–110 PPI range, because the priority shifts to maximizing surface area for catalyst loading per unit volume. The trade-off runs in the opposite direction from filtration: finer pores mean more surface area and more reaction sites, but also a greater risk of gas bubbles becoming trapped inside the structure if the pore network isn't well interconnected. Getting this balance right is a real materials engineering decision, not a catalog lookup.

Why This Is the Fastest-Growing Segment for Nickel Foam

Nickel foam has been a known material in NiMH batteries and industrial filtration for decades. What has changed is the scale of the electrolyzer buildout it now feeds. The European Union's hydrogen strategy targets tens of gigawatts of installed electrolyzer capacity this decade. Saudi Arabia's NEOM green hydrogen complex alone represents a 2.2 GW alkaline electrolyzer commitment. Multiple market analyses tracking the electrolyzer supply chain now place electrolyzer applications at an estimated 55–65% share of global nickel foam electrode substrate demand by value as of 2026 — a level that would have been unthinkable a decade ago, when batteries and filtration dominated demand.

For hood and equipment manufacturers who already know nickel foam from filtration or EMI shielding applications, the practical takeaway is this: the same base material family is now being pulled into a much larger, faster-growing market, and the specification requirements are different enough (finer PPI, higher surface area, electrolyte compatibility) that they're worth understanding before assuming a filtration-grade product will work as an electrode substrate.

Nickel Foam: Filtration Grade vs. Electrolyzer Grade

Both grades start from the same manufacturing process family — electrodeposition of nickel onto a polymer foam template, followed by pyrolysis and sintering to leave a pure metallic nickel scaffold — but the template pore size, foam density, and post-processing are tuned differently for each end use.

Related: Nickel Foam Applications & Sourcing

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