What is the material hydrogen fuel cell?
A hydrogen fuel cell is an electrochemical device that converts hydrogen and oxygen directly into electricity, with water as the primary emission. It relies on layered materials—an electrolyte membrane, electrodes with catalysts, and supporting hardware—to drive the chemical reaction efficiently.
In practice, the material choices define performance, cost, and durability. This article surveys the main materials used in common hydrogen fuel cell designs, explains how they work together, and highlights current advances that are expanding applications in transport, stationary power, and beyond.
How a hydrogen fuel cell works
At the anode, hydrogen molecules are split into protons and electrons. The electrolyte membrane allows protons to pass to the cathode while electrons travel through an external electrical circuit, producing electricity. At the cathode, protons, electrons, and oxygen from the air combine to form water. This electrochemical process produces electricity with water as the main byproduct, rather than combustion exhaust.
Key materials and components
These are the essential materials and components that make the cell function.
- Electrolyte membrane or solid electrolyte: The medium that conducts ions between electrodes while separating fuels. In PEM fuel cells, this is a polymer membrane (commonly Nafion-based) that conducts protons.
- Electrodes and catalysts: The anode and cathode surfaces host catalysts that accelerate hydrogen oxidation and oxygen reduction. Platinum-group metals are common, often supported on carbon. Research is expanding to non-precious metal catalysts to reduce costs.
- Gas diffusion layers (GDL) and electrode fabric: Porous carbon-based layers that distribute reacting gases evenly and conduct electrons between the catalyst and the current collector.
- Bipolar plates and flow-field hardware: Structural components that route hydrogen and oxidant to the cell, collect current, and manage heat. Materials include graphite and coated metals with corrosion-resistant surfaces.
- Seals, gaskets, and cooling system components: Polymers and elastomers to prevent leaks, and cooling channels or manifolds to remove waste heat and maintain performance.
These materials determine how efficiently a hydrogen fuel cell converts fuel to electricity, how long it lasts in real-world conditions, and how much it costs to manufacture and maintain.
Common fuel cell chemistries and their materials
Different technologies use different electrolytes and materials. The most common types today include PEMFCs, but several other chemistries are important in niche or transitional roles.
Proton Exchange Membrane Fuel Cells (PEMFCs)
PEMFCs use a solid polymer electrolyte (often Nafion) and typically operate at 60–80°C, though newer variants push higher. Key materials include the Nafion membrane, platinum-based catalysts for both the anode and cathode, carbon-based gas diffusion layers, and metal or graphite bipolar plates with sealed, humidified operation. Advances aim to reduce Pt loading and improve membrane durability under varying humidity and temperature.
Phosphoric Acid Fuel Cells (PAFCs)
PAFCs employ a liquid phosphoric acid electrolyte immobilized within a silica support, generally operating around 150–200°C. Materials of note include phosphoric acid–impregnated structures, Pt catalysts, nickel-based or other durable electrodes, and robust graphite or metal flow-field plates. These cells are closer to commercial use in stationary power applications.
Solid Oxide Fuel Cells (SOFCs)
SOFCs use a ceramic electrolyte, typically yttria-stabilized zirconia (YSZ), and operate at high temperatures (about 700–1000°C). The anode is often a nickel–YSZ cermet, the cathode a transition-metal oxide such as LSM or LSCF, and the interconnects are ceramic or metal. Materials research focuses on reducing operating temperatures, enabling cheaper interconnects, and shortening start-up times while preserving durability.
Molten Carbonate Fuel Cells (MCFCs)
MCFCs utilize a molten carbonate salt electrolyte, typically circulating lithium, potassium, or sodium carbonates, at high temperatures (around 650°C). The anode is usually nickel-based, with various oxide or carbonate cathodes. Materials emphasis includes corrosion resistance, electrolyte management, and long-term stability of the carbonate mixture under flow conditions.
Alkaline Fuel Cells (AFCs)
AFCs use an alkaline electrolyte (often potassium hydroxide in aqueous form) and historically provided high efficiency with non-precious metal catalysts. They require careful CO2 management to prevent carbonate formation. Material considerations include durable alkaline electrolytes, effective gas diffusion layers, and affordable catalysts that resist poisoning.
Material challenges and ongoing research
Researchers are pursuing lower-cost catalysts (reducing or replacing platinum), more durable membranes and electrolytes that tolerate humidity and temperature swings, and lightweight, corrosion-resistant bipolar plates. Advances in carbon supports, nano-engineered catalysts, and alternative membrane chemistries aim to improve performance, reliability, and scalability for vehicles, backup power, and grid storage.
Summary
Hydrogen fuel cells are built from a combination of electrolytes, electrodes with catalysts, and supporting hardware that convert hydrogen and oxygen into electricity with water as the only major byproduct. The exact materials vary by fuel cell type, with PEM, PAFC, SOFC, MCFC, and AFC representing the main families. Ongoing material science efforts target cheaper catalysts, tougher membranes, and more durable, cost-effective components to broaden adoption across transportation, stationary power, and beyond.
Can you drink the water from a hydrogen fuel cell?
The answer is a bit mixed. Generally speaking, the water should be safe to drink, in theory. One study found the water quality produced by two commercial fuel cells met nearly all drinking water requirements from the World Health Organization and the U.S. Environmental Protection Agency.
What is the raw material for hydrogen fuel?
Steam methane reforming (SMR) produces hydrogen from natural gas, mostly methane (CH4), and water. It is the cheapest source of industrial hydrogen, being the source of nearly 50% of the world's hydrogen.
What materials are hydrogen fuel cells made of?
The main materials used in fuel cells are Nafion, Teflon, Silicone Rubber, Platinum, Graphite, carbon paper, and carbon fiber.
What is the biggest problem with hydrogen fuel?
One major concern is safety, as hydrogen is highly flammable and its invisible flames are difficult to detect. Another major concern is leakage, because hydrogen molecules are so small that they can easily escape through seals and react in the atmosphere to cause warming effects, and it can also make pipelines brittle, increasing the risk of rupture.
Safety and leakage
- High flammability: Hydrogen can ignite easily from sparks or static electricity, and it burns more rapidly than natural gas, sometimes with explosive results.
- Invisible flames: Hydrogen flames are nearly invisible to the human eye, making it hard to see leaks or fires, especially at night.
- Brittle pipelines: The use of hydrogen can cause materials like steel, commonly used in existing natural gas pipelines, to become brittle and fail over time, leading to leaks and ruptures.
- Undetected leaks: Due to its small molecule size, hydrogen can easily leak through seals and existing infrastructure. A significant portion of hydrogen accidents are caused by undetected leaks, according to Issues in Science and Technology.
Atmospheric impact
- Greenhouse gas effect: When hydrogen leaks into the atmosphere, it triggers chemical reactions that increase the concentration of other greenhouse gases, like methane and ozone, leading to warming. This can significantly reduce the climate benefits of using hydrogen, notes the Environmental Defense Fund.
- Leakage prevention is crucial: To maintain its climate benefits, minimizing leaks is critical. This requires special equipment and robust monitoring systems, says World Resources Institute.
