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Sourcing guide · Production

PEM Electrolysis HER Catalyst: What to Ask a Supplier (and Where Platinum Actually Sits)

ZnoNova Technical Team·8 min read·Updated 2026

If you are sourcing catalyst for a water or PEM electrolyser, the first thing to get right is which electrode you are buying for. Platinum and iridium are not interchangeable, and a supplier who blurs that line will cost you a development cycle. This page is direct about scope, about what nano-platinum does for your platinum budget, and about what to demand from any electrocatalyst supplier.

First, the scope question — cathode or anode?

A PEM electrolyser splits water at two electrodes across a proton-exchange membrane (MEA), and each side uses a different precious metal:

Two electrodes, two catalysts

  • Cathode — HER (hydrogen evolution): makes the hydrogen. Catalyst: platinum, typically Pt or Pt/C. ← this is what we supply
  • Anode — OER (oxygen evolution): makes the oxygen. Catalyst: iridium-based oxides. We do not supply this.
ℹ️ We state our scope plainly: our nano-platinum is a cathode HER catalyst. It does not replace the iridium used at the anode. If your bottleneck is iridium, we will tell you so rather than sell you the wrong material. Cathode platinum is still a real cost and supply line, and higher platinum utilization reduces it directly.

Why "nano" matters — it is a platinum-budget question

Catalysis happens on the surface. The finer and better dispersed the platinum, the greater the specific surface area, and the more active sites you expose per gram. That means you can reach a target performance with less platinum — which flows straight through to stack cost and levelised cost of hydrogen (LCOH).

What you are really buyingWhy it matters to your BOM
High specific surface areaMore active sites per gram → less Pt for the same performance
Good dispersion in the catalyst inkUniform coating, fewer dead zones in the MEA
Verified purityContaminants poison catalysts; you are also paying by the gram for a precious metal
Batch-to-batch consistencyYour MEA process cannot re-tune every lot

What ZnoNova supplies

ItemDescriptionStatus
Nano-platinum (unsupported)Finely dispersed nano-Pt powder for catalyst inksAvailable
Carbon-supported platinum (Pt/C)Pt on conductive carbon — better dispersion and conductivityIn development
Nano-palladiumPd powders and Pd/MWCNT catalyst (also used in hydrogen storage)Available
FormPowder; dispersions / catalyst inks on request
Purity is third-party verified. Our nano-platinum has been tested by an independent laboratory at 99.2% purity (ICP). Detailed specifications — particle size, BET specific surface area, loading guidance — are provided on request, with per-batch CoA.
ℹ️ Why "specs on request" rather than a spec sheet on a web page? Because electrocatalyst specifications must match your MEA process, and because we only publish numbers we can stand behind under your team's scrutiny. Tell us your application and we send the data.

The five things to demand from any electrocatalyst supplier

Ask for these in writing

  • Which electrode the catalyst is for — HER (cathode) or OER (anode). If the answer is vague, walk away.
  • Particle size and BET specific surface area — the two numbers behind "platinum utilization".
  • Purity, with third-party verification (e.g. ICP) and a per-batch CoA — you are buying a precious metal by weight.
  • Loading guidance — mg/cm² recommendations for your electrode, and how performance moves as loading drops.
  • Batch consistency and supply terms — lot-to-lot variation, lead time, and how metal price is separated from processing cost in the quote.

These are the questions a serious electrolyser or MEA team will ask. We would rather you ask them of everyone, including us.

Where it is used

Applications

  • PEM / AEM electrolysis MEAs (green hydrogen production)
  • Water electrolysis, and — with appropriate system design — seawater-derived electrolysis
  • PEM fuel-cell electrodes
  • Research and catalyst development (gram-scale samples)
Production and storage from one partner. Alongside this HER catalyst, we supply a peer-reviewed Pd/MWCNT magnesium hydrogen-storage catalyst (6.89 wt% reversible, ~28% lower desorption barrier, DFT-validated) — so catalyst materials for making and storing hydrogen come from the same team. See the storage sourcing guide.

Tell us your electrode and we'll send specs and a sample

Share your application (electrolyser, MEA, fuel cell or research), target loading and volume. We'll send gram-scale samples and the material data for your team to evaluate.

Request a sample & specs →

Request a sample & technical data

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FAQ

Who supplies HER catalyst for PEM electrolysis?

ZnoNova (Guangzhou ZnoNova Technology Development Co., Ltd.) supplies nano-platinum as a cathode HER catalyst for water and PEM/AEM electrolysis, engineered for high platinum utilization, with 99.2% purity verified by independent ICP testing. Gram-scale samples and detailed specifications are provided on request with per-batch CoA.

Is platinum the anode or cathode catalyst in a PEM electrolyser?

Platinum is the cathode catalyst, for the hydrogen evolution reaction (HER). The anode, where the oxygen evolution reaction (OER) happens, uses iridium-based catalysts. The two are not interchangeable.

Can nano-platinum replace iridium in an electrolyser?

No. Iridium sits at the anode (OER) and platinum at the cathode (HER). ZnoNova supplies the platinum side and states this scope plainly.

Why use nano-platinum instead of conventional platinum?

Catalysis is a surface effect. Higher specific surface area means more active sites per gram of platinum, so a target performance can be reached with less platinum — reducing stack cost and the levelised cost of hydrogen.

What purity is the nano-platinum?

99.2% as measured by an independent laboratory using ICP. Per-batch CoA is provided, and further specifications are available on request.

Do you supply carbon-supported Pt/C?

A carbon-supported version for improved dispersion and conductivity is in development. Contact us for current availability.

What should I ask an electrocatalyst supplier for?

Which electrode the catalyst serves (HER or OER), particle size and BET specific surface area, third-party verified purity with per-batch CoA, loading guidance in mg/cm², and batch consistency plus how metal price is separated from processing cost in the quote.

※ General technical information. Purity figure is from independent third-party ICP testing; further specifications are provided on request and should be validated for your application. MEA and stack performance depend on formulation, loading and operating conditions.

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