Low-temperature water electrolysis for green hydrogen requires catalysts that lower overpotentials for the hydrogen evolution reaction and the oxygen evolution reaction while remaining durable and low-cost. Researchers and national laboratories focus on both noble metals for small, high-performance systems and earth-abundant materials for scalable, territorial deployment.
Catalysts and mechanisms
For proton exchange membrane systems, platinum for the hydrogen evolution reaction and iridium oxide for the oxygen evolution reaction remain benchmarks because they combine high activity and corrosion resistance. Jens Nørskov Technical University of Denmark has emphasized through theoretical and experimental work that tuning the hydrogen adsorption energy on catalyst surfaces governs activity, producing the volcano relationship that guides catalyst selection. For alkaline electrolysis and emerging anion exchange membrane cells, nickel and nickel-iron oxyhydroxides provide competitive activity at much lower cost. Ib Chorkendorff Technical University of Denmark has demonstrated how nanostructuring and controlled oxidation states improve active surface area and stability in those systems. Transition metal phosphides, sulfides, nitrides, and doped perovskite or spinel oxides are promising because they combine electronic structure control with lower reliance on scarce metals. These alternative materials often require careful synthesis and interface engineering to match noble-metal performance.
Catalyst supports, conductive layers, and ionomer interactions also function as catalysts of efficiency by influencing electron transport and mass transfer. John A. Turner National Renewable Energy Laboratory has highlighted that membrane resistance, catalyst layer porosity, and water management often limit system efficiency as much as intrinsic catalytic activity. Thus catalyst development and cell engineering must progress together.
Practical implications and context
The choice of catalyst affects cost, supply chains, and environmental impacts. Reliance on iridium and platinum raises territorial and social concerns because those metals are scarce and concentrated geographically, which can drive price volatility and mining-related environmental harm. Shifting to earth-abundant catalysts reduces those risks but introduces challenges in long-term durability and scaling. Improved catalyst activity lowers required cell voltage, reducing electricity consumption and greenhouse gas footprint when powered by renewables, which is central to decarbonizing heavy industry and storing variable renewable energy. Adoption pathways will vary by region depending on local renewable resources, industrial needs, and access to critical materials.