Green Hydrogen Could Go Mainstream with Cheaper Catalysts
As the global energy sector races toward net zero, hydrogen has stepped into the limelight as a clean and adaptable energy carrier. Among the production methods, proton exchange membrane water electrolysers (PEMWE) are winning favour for their ability to generate high-purity hydrogen directly from renewable electricity. Yet, there’s a snag: the heavy reliance on iridium and ruthenium, two noble metals that are scarce and eye-wateringly expensive.
These critical raw materials are the backbone of the acidic oxygen evolution reaction (OER) in PEMWE systems. While alternatives made from non-noble metals (NNMCs) are emerging, they’ve yet to match the performance and longevity required for real-world deployment. Stability under acidic conditions, in particular, remains a stumbling block.
A major review published in eScience by researchers at the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, brings this challenge into sharp focus. It offers a deep dive into catalyst design strategies, degradation mechanisms, and innovative solutions to reduce dependence on noble metals without sacrificing performance.
Inside the Science: Cracking the Acidic OER Code
The review explores the two primary mechanistic pathways of acidic OER:
- Water Hydrogen Atom Abstraction (WHAA) – where reaction intermediates hinge on precise hydrogen removal from water molecules.
- Direct Coupling Mechanism (DCM) – involving direct formation of oxygen-oxygen bonds from adsorbed species.
Both are highly sensitive to a catalyst’s surface structure and electronic configuration. And here lies the rub: traditional thermodynamic models can’t fully capture the complexity of real-time reaction kinetics. This is where advanced in situ characterisation and molecular simulations come into play, offering a clearer window into the reaction’s inner workings.
“To replace noble metals in acidic electrolysis, we must first understand what limits the performance of alternative materials,” said Dr Meiling Xiao, co-corresponding author of the review. “Our work consolidates years of fragmented research into a coherent framework that identifies where the true challenges lie—whether in electronic structure, surface stability, or reaction dynamics.”
Fighting Corrosion: Strategies for Stability
If activity is one half of the equation, stability is the other. Non-noble metal catalysts often succumb to dissolution or irreversible oxidation under acidic conditions. To counter this, researchers are deploying several clever approaches:
- Self-healing catalysts – systems that regenerate their active sites during operation.
- Acid-stable oxide incorporation – adding phases such as titanium or tantalum oxides to protect the core catalyst.
- Anion doping – using high-oxidation-potential anions like fluorine to boost durability.
Recent breakthroughs are particularly promising. Co–Mn oxides, fluorine-doped MnO₂, and high-entropy alloys have shown both strong activity and prolonged operational life. By tailoring the structural and electronic properties, these materials are edging closer to matching, and potentially surpassing, noble metal-based systems.
High-Entropy Alloys: A Material Design Frontier
The review shines a spotlight on high-entropy alloys (HEAs) as a game-changing material category. Containing multiple principal elements in near-equal proportions, HEAs offer unique pathways for tuning electronic structures and improving corrosion resistance.
These alloys can be engineered to optimise the balance between catalytic activity and structural stability—critical in the harsh acidic environments of PEMWE systems. Early studies suggest HEAs could be a key building block for next-generation, low-cost hydrogen production technologies.
From Lab to Market: Bridging the Deployment Gap
Achieving lab-scale performance is one thing; translating it into market-ready systems is another. The review emphasises the need for:
- Scalable synthesis techniques for NNMCs.
- Durability testing under industrially relevant current densities.
- Integration studies to ensure compatibility with existing PEMWE designs.
These steps will be crucial in proving to investors and policymakers that NNMC-based systems can deliver on cost, performance, and reliability in commercial settings.
“By mapping the degradation pathways and pairing them with actionable design principles, we hope to accelerate the transition toward practical, affordable, and scalable hydrogen technologies,” added Dr Xiao.
The Bigger Picture: Driving Down the Cost of Green Hydrogen
If successful, the shift to NNMCs could significantly lower the cost of PEMWE systems, making green hydrogen far more competitive in global energy markets. Beyond power generation, these catalysts could feed into hydrogen refuelling stations, industrial energy storage, and even the decarbonisation of steel and chemical manufacturing.
The design principles outlined—particularly high-entropy material selection and fine-tuned electronic structures—could also influence other catalytic processes, from CO₂ reduction to ammonia synthesis. In short, this is not just about hydrogen; it’s about rethinking how we approach catalyst design across the clean energy sector.
A Blueprint for Affordable Hydrogen
The Changchun team’s work represents a major step toward breaking the noble metal bottleneck. By combining fundamental mechanistic understanding with cutting-edge material innovations, they’ve laid the groundwork for a new generation of cost-effective, durable catalysts.
With strong backing from national R&D programmes and provincial initiatives, the path from the lab bench to industrial-scale deployment looks increasingly achievable. As global demand for hydrogen surges, these insights could not be more timely.
