The Architect of the Atomic Landscape Powering Our Clean Energy Future
In the urgent global race towards clean energy, technologies like fuel cells that promise efficient, emission-free power often hinge on a hidden world—the realm of atoms and molecules where chemical reactions make or break their efficiency. For decades, Professor Jürgen Behm has been a master architect in this nanoscale world, building crucial bridges between fundamental surface science and applied energy technology. His pioneering work has been instrumental in designing the high-performance catalysts that are central to the hydrogen economy, transforming how we convert and store clean energy.
At the heart of any electrochemical device, such as a fuel cell, lies catalysis—the process of speeding up chemical reactions without being consumed itself. These reactions, like the Oxygen Reduction Reaction (ORR) that is crucial for fuel cells, occur on the surface of solid materials. To understand and improve these processes, scientists must see and understand the intricate dance of atoms and molecules on these surfaces.
Professor Behm's career is a testament to a "surface science approach." This methodology involves studying catalytic reactions on well-defined, pristine surfaces, often single crystals, under ultra-high vacuum conditions.
This controlled environment allows researchers to observe reactions at the atomic level using powerful techniques like Scanning Tunneling Microscopy (STM) and spectroscopy. As highlighted in the seminal work "Fuel Cell Catalysis: A Surface Science Approach," this approach is vital for a "molecular understanding of fuel cell catalysis," stripping away the complexity of real-world materials to reveal fundamental principles 1 .
Behm's early STM studies, such as his groundbreaking observation of the reconstructed gold (Au(111)) surface, provided the field with breathtaking clarity on atomic structure, rotational domains, and surface defects 1 .
Behm pioneered the use of model catalysts that mimic real-world complexity while allowing detailed analysis. His work on CO oxidation on gold nanoparticles showed how support materials can be "active" in reactions 1 .
Professor Behm's extensive publication record reveals a consistent focus on understanding and optimizing interfacial processes for energy applications. The following table summarizes the enduring impact of some of his most influential works.
| Research Focus | Key Finding | Significance & Impact |
|---|---|---|
| Surface Structure & Catalysis | Atomic-level imaging of surfaces like Au(111) and graphite formation on Pt(111) 1 . | Established how atomic arrangement and defects influence chemical reactivity. |
| Oxygen Reduction Reaction (ORR) | Thin-film rotating ring-disk electrode (RRDE) study on Pt/carbon catalysts 1 . | Provided a benchmark method for evaluating ORR activity and stability, critical for fuel cell cathodes. |
| Novel Catalyst Design | Demonstrated the role of "inert" supports in CO oxidation on gold catalysts 1 . | Redefined the design principles for supported metal catalysts, highlighting support-material interactions. |
| Bimetallic & Alloy Catalysts | Revealed the role of atomic ensembles in the reactivity of bimetallic electrocatalysts 1 . | Guided the development of more efficient and cost-effective alloy catalysts, reducing reliance on pure platinum. |
| Battery Interface Research | Fundamental study of processes at the electrode-electrolyte interface in lithium-ion batteries 2 . | Extended his surface science approach to energy storage, aiming to optimize battery performance and lifetime. |
Scientific Publications
Citations
Decades of Research
To truly appreciate Behm's methodology, let's examine one of his most cited and impactful experiments: "Oxygen reduction on a high-surface area Pt/Vulcan carbon catalyst: a thin-film rotating ring-disk electrode study" 1 3 .
The ORR at the fuel cell cathode is slow and requires platinum-based catalysts, a major cost driver. To develop better catalysts, researchers need an accurate way to measure two things simultaneously: 1) the kinetic rate of the desired reaction (oxygen to water), and 2) the amount of unwanted by-product (hydrogen peroxide, H₂O₂), which can degrade the fuel cell components.
The rotating ring-disk electrode allows simultaneous measurement of main reaction products and intermediates/by-products.
Behm and his team employed an elegant electrochemical tool known as a Thin-Film Rotating Ring-Disk Electrode (RRDE). The procedure can be broken down into clear steps:
A small amount of the practical catalyst—Pt nanoparticles on Vulcan carbon—is dispersed in a solution and carefully deposited as a thin, uniform film on a glassy carbon disk electrode 1 3 .
The prepared electrode is immersed in an electrolyte solution that mimics the fuel cell's acidic environment.
The electrode is rotated at high speeds. This controls the flow of oxygen to the catalyst surface, allowing scientists to distinguish between reaction kinetics and mass transport effects.
A changing electrical potential is applied to the disk electrode, driving the ORR.
On the Disk: The current required to reduce oxygen is measured.
On the Ring: A constant potential is set to detect any H₂O₂ produced at the disk. As H₂O₂ travels to the ring, it is oxidized, generating a measurable ring current.
The ratio of the ring and disk currents allows for the precise calculation of the H₂O₂ yield 3 .
This experiment provided a robust framework for quantifying catalyst performance. Key results and their importance are summarized below.
| Performance Metric | Typical Result for a Good Pt/C Catalyst | Scientific Importance |
|---|---|---|
| ORR Activity | High current density on the disk at a given potential. | Measures the catalyst's fundamental efficiency in driving the desired reaction. |
| H₂O₂ Yield | Low percentage (e.g., <2%) of the total oxygen reduced. | Indicates high reaction selectivity; minimizes catalyst and membrane degradation. |
| Onset Potential | The voltage at which the ORR current begins. A more positive potential is better. | Reveals the catalyst's ability to lower the energy barrier for the reaction. |
The journey from a fundamental discovery to an applied technology relies on a specific set of tools and materials. The following table details key components of the "research reagent solutions" used in Behm's field.
| Tool/Reagent | Function & Explanation |
|---|---|
| Single Crystal Surfaces (e.g., Pt(111), Au(111)) | Provide atomically flat, well-defined platforms to study the intrinsic activity of different surface structures without the complicating effects of edges or nanoparticles. |
| Model Catalysts (Nanoparticles on Supports) | Bridge the gap between single crystals and industrial catalysts. They allow for the study of "real-world" catalyst structures (size, shape, support effects) under controlled conditions. |
| High-Surface-Area Carbon (e.g., Vulcan XC-72) | A common catalyst support. Its high conductivity and surface area allow for the dispersion of tiny metal nanoparticles, maximizing the active surface area available for reactions. |
| Nafion® Ionomer | A proton-conducting polymer. In thin-film electrode preparation, it binds the catalyst layer and facilitates the transport of protons to and from the active sites, mimicking the fuel cell environment. |
| Rotating Ring-Disk Electrode (RRDE) | The key apparatus for simultaneous measurement of a main reaction (on the disk) and its reaction intermediates or by-products (on the ring), as detailed in the experiment above. |
| Scanning Tunneling Microscope (STM) | Allows for real-space imaging of surfaces with atomic resolution. It is indispensable for characterizing model surfaces and understanding how molecules adsorb and form structures. |
Atomic resolution imaging of catalyst surfaces.
Precise measurement of catalytic activity.
Well-defined systems bridging theory and application.
Professor Jürgen Behm's career is a powerful case study in how deep, fundamental science provides the essential foundation for technological progress. By meticulously building bridges from the atomic-scale world of surface science to the applied realm of catalysis and fuel cell research, he has provided the insights and tools needed to engineer more efficient, durable, and affordable energy conversion systems.
His legacy continues to shape the field. At the Helmholtz Institute Ulm (HIU), his research group now focuses on the electrode-electrolyte interface in lithium-ion batteries 2 . Here, they again apply their signature approach—using model systems and sophisticated techniques like STM and XPS to unravel complex processes at the molecular scale.
This work is vital for developing batteries with higher energy density, longer life, and faster charging capabilities.
From mapping the atomic terrain of gold and platinum to optimizing the interfaces in next-generation batteries and fuel cells, Jürgen Behm's work ensures that the tiny bridges he built between fundamental and applied science will continue to support the weight of our clean energy future.