Beyond iridium: how AEM electrolysers could unlock large-scale Power-to-X

The story of green hydrogen often skips over an awkward problem: the electrolyser technology most often discussed for renewable-electricity coupling – proton exchange membrane (PEM) electrolysis – depends on iridium, one of the rarest and most expensive metals on Earth. As Power-to-X targets scale to gigawatts globally, iridium supply becomes a real constraint. A research breakthrough published in Nature Catalysis in late 2024 brings a credible alternative materially closer.

The three electrolyser families, briefly

Three water electrolysis technologies dominate the conversation. Alkaline electrolysis is the oldest, uses cheap nickel-based electrodes in a liquid potassium hydroxide solution, and works well at steady-state operation but adapts poorly to the fast load fluctuations of solar and wind. Proton exchange membrane (PEM) electrolysis uses a solid polymer membrane and platinum-group metal catalysts – critically, iridium for the oxygen evolution anode – and handles variable renewable power excellently, but iridium is expensive and supply-constrained. Anion exchange membrane (AEM) electrolysis is the newer arrival: a solid membrane like PEM (for flexibility under variable power) but operating in alkaline chemistry like classical electrolysers (so that cheap nickel-based catalysts can be used instead of iridium).

On paper, AEM combines the best of both. In practice, the materials have not until recently performed at PEM-level efficiency. That is what changed in October 2024.

The Berlin-Freiburg-Siemens Energy result

A research consortium led by Technical University of Berlin and the Helmholtz-Zentrum Berlin (HZB), together with the IMTEK at the University of Freiburg and SPIN member Siemens Energy, published an AEM electrolyser cell that performs nearly as well as a PEM cell – without any iridium. The key innovation was a new family of nickel-based catalysts – NiX, where X is iron, cobalt or manganese – coated directly onto the alkaline ion exchange membrane in a scalable process.

Using operando X-ray measurements at the BESSY II synchrotron in Berlin, the team identified that the catalyst undergoes a phase transition during operation – from an inactive alpha phase to a highly active gamma phase containing redox-active nickel-oxygen ligands. “It is this gamma phase that makes our catalyst competitive with current state-of-the-art iridium catalysts,” said Prof. Peter Strasser of TU Berlin. A theory team in the US and Singapore contributed the molecular-level explanation. The work was published in Nature Catalysis (Klingenhof et al., 2024).

Two practical points stand out. First, the new catalyst-coated membrane process was developed with manufacturing scalability in mind – it is the kind of result that has a path from laboratory cell to industrial stack. Second, Siemens Energy’s participation in the consortium is not incidental. The group has a direct industrial route for evaluating and potentially scaling these materials, which is what distinguishes a publication from a development that actually reaches the market.

The broader AEM commercialisation picture

The Berlin result is not the only signal that AEM is moving from research to market. The Italian-German company Enapter has been shipping commercial iridium-free AEM electrolysers in modular configurations for several years, ranging from 2.4 kW single-core units to 1 MW stacks built from 420 individual modules. In 2025, Enapter formed a joint venture with the Chinese Wolong Group to scale up production.

In North America, the company Power To Hydrogen (P2H2) completed Phase I of an industrial-scale AEM stack demonstration with global utility partners and reports stack cost reductions of up to 70 percent compared with conventional electrolyser designs. The Canadian firm Cipher Neutron is commercialising AEM systems claiming stack efficiencies near 90 percent (higher heating value basis). And several other start-ups in China, Korea and Europe are building dedicated AEM production lines.

A study cited by CleanHyPro indicates a levelised cost of hydrogen of around EUR 1.29 per kilogram is achievable with mature AEM technology. The economics depend strongly on electricity price and capital cost trajectory, but the order of magnitude is now competitive.

Why this matters for Power-to-X

Two reasons.

First, supply chain resilience. The world produces roughly 7 to 8 tonnes of iridium per year, almost entirely as a by-product of South African platinum mining. A global green hydrogen build-out at the scale needed for Paris-compatible defossilisation would, with PEM-only assumptions, exhaust available iridium supply long before the production targets are met. AEM removes that constraint. AEM stacks based on nickel, cobalt or iron use materials with much more geographically distributed supply chains – a different risk profile for energy-transition infrastructure.

Second, capital cost. Iridium can account for a significant share of PEM stack cost, especially at the rare-metal price spikes that recurring supply constraints tend to produce. Eliminating it changes the cost curve of electrolyser capacity.

Honest caveats

AEM is not yet a solved technology. Membrane durability under industrial-scale conditions is still being demonstrated. Many candidate nickel-foam-based components are vulnerable to corrosion over long operating lifetimes in concentrated alkaline solutions. The Nature Catalysis result is a laboratory cell demonstration, not a commercial stack. Industrialisation will require years of further engineering work, durability testing, and scaling up component supply chains.

That said, the situation is no longer one of “if” but “when”. The technology now exists with credible performance, with an industrial partner, with multiple commercial vendors at varying degrees of scale, and with credible cost trajectories. The next several years will determine how quickly AEM moves from the present several-percent share of the global electrolyser market into a major position.

SPIN Perspective

From a Swiss vantage point, the AEM story matters as a reminder that Power-to-X is not just about end-products and policies; it is also about the unglamorous engineering challenges that determine whether a vision is buildable. Iridium availability is one of the technical constraints that the Power-to-X community has had to live with, manage around, or hope would be resolved by R&D. With work like the Nature Catalysis 2024 result, the latter outcome is now visibly arriving.

For Switzerland’s industrial ecosystem – with its strong precision engineering, materials science, and chemical industry traditions – the electrolyser supply chain is one of the more interesting Power-to-X value-chain positions to occupy. Components, coatings, balance-of-plant equipment, control systems, and certification services for AEM stacks are areas where Swiss specialisation can be applied to a globally growing market. As the technology matures, that opportunity becomes more concrete.

Source: Klingenhof et al., “High-performance anion-exchange membrane water electrolysers using NiX (X = Fe, Co, Mn) catalyst-coated membranes with redox-active Ni–O ligands”, Nature Catalysis, October 2024. Coverage: HZB, ScienceDaily. Industry context: CleanHyPro, Enapter.