CRITICAL ROLE OF PRECIOUS METALS IN HYDROGEN ENERGY: UNDERSTANDING THE SCIENCE BEHIND CLEAN TECHNOLOGY

By LIU FENG, Chairman and General Manager of Sino-Platinum Metals New Energy Technology (Shanghai) Co., Ltd; Deputy General Manager of Yunnan Precious Metals Materials Laboratory Co., Ltd.

Amid the global push for carbon neutrality, hydrogen energy is regarded as one of the most promising clean energy sources, with catalytic materials as the foundational cornerstone of the hydrogen energy value chain. In the two core segments of this chain—hydrogen production (via PEM water electrolysis) and hydrogen utilization (via fuel cells)—precious metal catalysts play an irreplaceable role.

The Scientific Foundation: Why Precious Metals Are Indispensable

During PEM electrolysis, iridium-based catalysts demonstrate unparalleled performance: they are currently the only materials capable of maintaining high catalytic activity and structural stability under strongly acidic, highly oxidative, and high-temperature conditions. This makes them a critical component for the efficient operation of proton exchange membrane electrolyzers.

In fuel cells, platinum-based catalysts deliver a precise balance of essential properties, including catalytic activity, chemical stability, and long-term durability. To date, no non-platinum-based material has been able to meet all three of these core requirements simultaneously. As a result, platinum-based catalysts remain an indispensable necessity for the commercial application of fuel cell technology.

As the world accelerates toward carbon neutrality, hydrogen energy has emerged as one of the most promising clean energy sources. At the heart of this industry lies catalytic materials – an indispensable foundation for the hydrogen energy value chain. Sino-Platinum Metals is leveraging its deep resources and technical expertise in precious metals to drive innovation, reshape the hydrogen energy landscape, and deliver comprehensive catalytic solutions across the entire hydrogen ecosystem, from production and storage to application.

Iridium Catalyst for PEM Water Electrolysis: The Driving Force Behind Green Hydrogen

Proton exchange membrane (PEM) electrolysis is one of the most advanced and environmentally friendly methods for hydrogen production. With fast responsiveness to fluctuating renewable power supply and zero carbon emissions, it is a key technology for producing “green hydrogen”.

The process involves three critical steps:

Anode reaction: Water molecules are oxidized at the anode, splitting into oxygen (O₂), protons (H⁺), and electrons (e^–).
Proton conduction: H⁺ ions pass through the proton exchange membrane.
Cathode reaction: H⁺ and e^– combine at the cathode to generate high-purity hydrogen (H₂).

Modern PEM catalysts feature iridium-based anodes (including iridium oxide, iridium black) and platinum-based cathodes (platinum on carbon). These catalysts are engineered for high surface area, abundant active sites, and exceptional catalytic performance. They also demonstrate strong resistance to oxidation, acid, and alkaline corrosion. The catalyst inks can be customised for different electrolyser designs, allowing for optimisation based on specific operational requirements and system configurations.

The PEM water electrolysis process utilises iridium-based anodized iridium catalysts for optimal performance under extreme conditions.

Platinum Catalyst for PEM Fuel Cells: Efficient Power Conversion

Fuel cells are not traditional batteries but energy converters that continuously generate electricity from chemical reactions. This fundamental difference allows them to operate continuously as long as fuel is supplied.

The electrochemical conversion occurs through two simultaneous reactions:

Anode (hydrogen side): H₂ molecules split into H⁺ and e^– on the catalyst surface.
Cathode (oxygen side): O₂ reacts with H⁺ and e^– to form water, releasing electricity in the process.

Compared to combustion engines, hydrogen fuel cells achieve over 60% energy conversion efficiency with only water as the emission, making them a truly zero-emission power source. They are widely used in hydrogen-powered vehicles, drones, ships, stationary power stations, and backup systems. Modern fuel cell catalysts include high-performance platinum on carbon (Pt/C) catalysts (Pt loading ≥ 50%) for maximum efficiency, and doped Pt-Co alloy catalysts with enhanced resistance to catalyst poisoning, extending operational life.

Platinum-based catalysts for proton exchange membrane fuel cells represent the current state-of-the-art in electrochemical energy conversion.

These catalysts feature 2–5 nm platinum nanoparticles with uniform distribution and minimal impurities. They meet commercial standards in electrochemical surface area (ECSA), mass activity (MA), power output, and durability.

Hydrogen Purification: Palladium Catalysts for Ultra-Pure Hydrogen

Hydrogen produced through industrial processes often contains trace impurities such as oxygen (O2) and carbon monoxide (CO). However, ultra-pure hydrogen (≥ 99.999%) is essential for sensitive applications like fuel cells and semiconductor manufacturing, where even minimal contamination can cause system failure or performance degradation.

The purification process leverages palladium’s unique crystalline properties:

Selective absorption: Hydrogen atoms (H^–), with a diameter of just 0.046 nm, can diffuse into the palladium crystal lattice.
Size exclusion: Larger gas molecules (e.g., O₂, CO) cannot penetrate the palladium structure, effectively filtering them out.

Modern palladium catalysts leverage Pd’s unique crystalline properties. The palladium nanoparticles are uniformly distributed on high-porosity alumina (Al2O3) spheres, offering high catalytic activity, thermal stability, and robust performance under harsh flow and temperature fluctuations. These catalysts are now widely used for hydrogen purification downstream of electrolysers and play a critical role in the ultra-pure hydrogen supply chain.

Paving the Way for the Green Hydrogen Economy

Global reserves of precious metals such as iridium and platinum are largely concentrated in countries like South Africa and Russia. As the hydrogen energy sector rapidly grows, the shortage of these critical resources is becoming increasingly acute, posing a major challenge to the sustainable development of the industry.

To address this key bottleneck, the industry has been investing heavily in the development of recycling technologies for hydrogen-related materials. Advanced systems have achieved:

Efficient recovery: Successfully recovering and purifying precious metals from core components such as catalysts and membrane electrode assemblies (MEAs).
Cost reduction: These advancements not only reduce dependency on primary resources but also significantly lower production costs.
Enhancing the circular economy: Supporting sustainable growth within the hydrogen value chain.

Building a Sustainable Hydrogen Future

The hydrogen economy represents one of the most promising pathways to achieving global carbon neutrality goals. Precious metal catalysts—iridium for hydrogen production, platinum for fuel cells, and palladium for purification—form the technological backbone that makes this clean energy future possible.

While supply constraints and costs present ongoing challenges, continued innovation in catalyst design, system integration, and recycling technologies is paving the way for sustainable growth. The combination of materials science expertise and strategic resource management will be essential for realising the full potential of hydrogen as a clean energy solution.

As the world accelerates toward a carbon-neutral future, understanding the critical role of these materials helps stakeholders make informed decisions about supporting the hydrogen energy transition. Through continued technological advancement and sustainable resource management, the hydrogen economy can deliver both environmental benefits and economic growth, one catalyst at a time.

LIU FENG is the Chairman and General Manager of Sino-Platinum Metals New Energy Technology (Shanghai) Co., Ltd,. He is a research fellow and master’s supervisor, and holds a Ph.D. in Science from Xiamen University. Dr. Liu has published over 50 academic papers (including 20+ in SCI/EI journals). He holds over 10 patents, has authored one monograph, and has supervised more than 10 master’s students. Furthermore, he has also led over 20 national and regional research projects. With a focus on national new materials development and market needs, Dr. Liu has developed and industrialized a series of innovative catalysts for environmental and hydrogen energy applications.