PEM electrolysis

Alkaline and solid oxide electrolysis are two alternative technologies, whereas proton exchange membrane (PEM) electrolysis is increasingly gaining traction. It is expected that PEM electrolysis will play an important role in the transition towards a hydrogen economy.

Due to their excellent dynamic response time PEM electrolyzers are a perfect solution for storing curtailed, excessive renewable energy. Moreover, the advantage of high current density operation allows production of more Hydrogen from smaller set-ups compared to alkaline electrolysis. Due to the high-pressure outlet of hydrogen, PEM electrolyzer technologies are directly connectable to gas stations.

The production of green hydrogen through PEM electrolysis of water is a very suitable concept to enable storage, transportation and deployment of the produced renewable energy. Scale-up and cost reduction of green hydrogen represent the essential steps towards reducing the world´s carbon dioxide footprint.

Heraeus' PEM electrolyzer catalyst portfolio

Heraeus has been committed to precious metals for more than 160 years. Utilizing our profound expertise in precious metal catalysts we are now providing PEM electrolyzer catalysts.

Our product portfolio includes electrolyzer catalysts with different precious metal loadings.

In order to find the perfect solution to your needs, we are able to test in our fully equipped on-site laboratories and test center.


Iridium Black

Iridium Dioxide

Next Generation Low Iridium

Iridium Ruthenium Mix Oxide







High metal purity

High surface area material

Reduced Ir content, supported material

Reduced Ir content

Performance focus

Highly active, stable

Highly active, highly stable

Excellent activity and material efficiency

Excellent activity and material efficiency

BET surface area [m2/g]

21 - 25

175 – 195

20 – 150

120 – 200

Mass activity @ 1.45 Vcell (iR-free)* [A/g]

~ 79

~ 86

~ 570 (30%)

~ 400 (Ir0.3Ru0.7)
online available online available online available
45% Ir
35% Ir
30% Ir
10% Ir
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80°C, 5 cm² cell; anode 0.3 mg/cm²

Save 50–90% on Iridium compared to the market’s benchmark

We achieved breakthrough innovation by developing PEM electrolyzer catalysts with significantly reduced precious metal loading. H2-EL-xxIrO-S, our latest development, will provide you with an up to three times higher catalyst performance while reducing the precious metal loading in the CCM by 50–90% in comparison to earlier generations.

Left: Iridium content benchmark; Right: Necessary electrode area benchmark

Discover more about Heraeus Hydrogen Systems

Julia Keck

Dr. Julia Keck

Global Head of Sales Hydrogen Systems

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Our Hydrogen Systems Team is looking forward to answer your questions