Dierk Raabe: Scientific Mission Statement

Professor Dierk Raabe works on the basic and applied science behind Sustainable Development with disruptive and transformative contributions to the fields of sustainable materials science, green metallurgy, recycling of critical and strategic elements, and circular production. He has redefined our understanding of metallic materials and has translated that knowledge from basic research into actionable, high-impact and industrially scalable solutions aimed at one of the most urgent challenges of our time: decarbonizing and circularizing the global metallurgical and downstream manufacturing sectors.

The magnitude of this challenge is staggering. Each year, humanity produces roughly 2 billion tons of metals, a process that consumes about 10% of the global energy supply and accounts for about 40% of all industrial greenhouse gas emissions, nearly 10% of the total global CO₂ emissions. These figures underscore the unique leverage point that a sustainable metals sector can offer in combating climate change and global pollution.
In this context, Dierk Raabe has systematically identified and addressed those research questions with the highest lever, establishing a new scientific field, coined as the ‘Materials Science of Sustainable Metals’. He developed this field along several pillars, as outlined in his landmark papers (Chem. Rev. 123, p. 2436 (2023); Nature 575, p. 64 (2019)), namely, sustainable (1) primary synthesis (extracting metals from mineral ores using hydrogen (plasma) and ammonia instead of fossil reductants); (2) secondary synthesis (new alloys from contaminated post-consumer scrap); (3) tertiary synthesis (sustainable metal extraction from toxic industry waste); (4) single-step synthesis and material design (co-reduction of mixed feedstock directly into ready-to-deploy alloys); and (5) sustainable critical element retrieval from strategic industry products (e.g. recycling of rare earth hard magnets).

Before Raabe’s interventions, the Materials Science of Sustainable Metals was largely addressed from process-engineering and life-cycle perspectives. His work reframed the problem as one of fundamental materials science: tackling the underlying thermodynamics, kinetics, atomic scale mechanisms, and structure-property relations that are required to identify, understand and scale engineering solutions for mitigating emissions, cutting energy consumption, enhancing recyclability, and developing a resource-efficient materials sector. This “first-principles” to material sustainability approach laid out the critical scientific bottlenecks—from the foundations of fossil-free plasma chemical reduction methods, sustainable post-consumer scrap recycling into composition-tolerant alloys that remain functional even when made from low-quality feedstock, to hydrogen-based co-reduction processes, in which ready-to-use alloys are directly produced from thermodynamically guided gas-solid and solid-solid co-reduction.

He categorized these methods by element and alloy families along crisp thermodynamic and kinetic bounds, identifying research strategies for steel, aluminum, copper, nickel, and critical & rare metals. His framework has become a blueprint for multiple research programs worldwide, aligning basic materials science with global climate targets. A few scientific breakthroughs are outlined below:

1. Primary Synthesis: Sustainable Metals from Ores by Hydrogen Plasma Reduction
The world’s metal demand cannot be satisfied by recycling scrap alone (satisfies only 1/3 of global demand for steels and aluminium, for most elements much less). This means metals must be produced to at least 2/3rds via synthesis from mineral feedstock, i.e. from ores. Among these processes, global steel production via blast furnaces emits alone ~7% of global CO₂. By combining experimental metallurgy with computational thermodynamics, Raabe has mapped the kinetic and energetic landscapes of hydrogen (plasma) and ammonia reduction, enabling reactor designs that minimize energy use while maintaining high mass throughput.

Exemplary is Raabe’s research on hydrogen-based plasma reduction of oxides as a scalable pathway to eliminate carbon reductants. His recent paper on sustainable nickel synthesis (as needed e.g. in batteries) enabled by hydrogen plasma reduction expanded this concept beyond steel, demonstrating that hydrogen metallurgy can address a broad variety of CO₂-intensive elements (Nature 641, p. 365 (2025)). This approach is transformative because plasma chemistry balances chemical energy in the form of hydrogen with direct use of electrical energy, bringing hydrogen into a highly reactive state. This shifts the energy-intensive production of hydrogen towards direct use of electrons. The solution is scalable as large electric arc plasma furnaces exist and less than 10% hydrogen partial pressure is needed to realize the concept.

2. Secondary Synthesis: The ‘Science of Dirty Alloys’– Infinite Recycling from Scrap

Making alloys from scrap has the highest potential to mitigate CO2 emissions in metal production, however, the huge challenge is that most scrap today (>70%) is highly contaminated post-consumer scrap. This means that alloy synthesis and design must embrace this fact while omitting chemical cleaning, owing to the high energy demand. This has motivated Raabe to develop a new research field which is today called ‘Science of Dirty Alloys’ (Prog. Mater. Sci. 128, p. 100947 (2022); Annual Rev. of Mater. Res. 54, p. 247 (2024)).
These works are about the two largest metal groups, steel and aluminium, standing for more than 1.9 billion tons produced per year. Raabe’s concept of ‘Dirty Alloys’ is a disruptive paradigm shift in alloy design that embraces, rather than resists, the presence of tramp elements from scrap. By understanding how contaminants interact with precipitation kinetics, phase stability, corrosion behavior, and mechanical performance, Raabe devised pathways to engineer alloys inherently tolerant of compositional variation, making them fit for endless recycling. This approach has fundamentally changed the way how alloys are designed.
The implications are transformative: for example, aluminum alloys produced entirely from scrap can reduce both energy consumption and CO₂ emissions by over 90% compared to primary production from oxides, while enabling closed-loop recycling in mass-market applications like vehicles and packaging. This approach not only closes the materials cycle but also stabilizes raw material supply in the face of geopolitical and environmental constraints.

3. Tertiary Synthesis: Turning Industrial Waste into Metal Feedstock
In another disruptive line of research, Raabe developed low-pressure (10%) hydrogen plasma methods to sustainably extract metals from poisonous industry waste products. One example is the extraction of iron, titanium, and rare elements from red mud, a toxic 4-billion ton by-product of aluminum refining (Nature 625, p. 703 (2024)). By converting such hazardous industry waste into high-value metal feedstock, he addresses two sustainability imperatives simultaneously: reducing the need for ore mining and remediating large-scale environmental hazards. This approach exemplifies the tertiary resource economy, a concept developed by Raabe, where industrial residues are re-defined as urban industry mines.

4. One-step synthesis and material design: in one process from oxides to products
Raabe and his coworkers also developed a new approach by making ‘ready-to-use’ alloys directly from ores, in one step (Nature 633, p. 816 (2024)). Here, Raabe demonstrates a radical departure from millennia-old practice: bypassing multi-stage refining by directly converting stoichiometrically mixed oxides via hydrogen-based co-reducing in the solid state into functional sustainable bulk alloys in a single step. This not only drastically reduces energy use and emissions but also opens a route to producing alloys from low-grade ores and waste streams that would otherwise be uneconomical to process. It also circumvents the need for heat treatment, reheating, and transport between downstream value-chain participants.

5. Sustainable Critical Element Retrieval from Strategic Industry Waste Products
Another approach of Raabe is to reclaim critical elements from dumped waste and scrap. One example is hydrogen-decrepitation recycling of heavy rare earth-based magnets. While the use of standard recycling leads to up to 21 % coercivity loss when used in new magnets, Raabe and coworkers have shown how to increase both the recycling rate and the performance of magnets made from such recycled material (Acta Materialia 283, 120532 (2025)), increasing coercivity by 35 % and even improving temperature coefficients beyond the original magnets. This closed-loop route enables reuse of advanced rare earth magnets with minimal performance penalty, reducing primary demand for strategic elements.
 
These examples document the huge effect of Raabe’s work for transformative global impact and a circular, sustainable economy. The systematic scientific basis of his innovations paired with a view on scalability is critical for sustainable development. Taken together, the technologies pioneered by Raabe offer routes to mitigating up to 10% of total global CO₂ emissions and 10% of global energy consumption, while securing the raw material base for the clean energy transition.
As Director of the newly established Max Planck Institute for Sustainable Materials, he has built one of the world’s premier centers for research on sustainable metals, fostering collaborations that bridge physics, modeling, artificial intelligence, microscopy, and pilot-scale processing. He trains the next generation of leaders in this field, having supervised over 50 postdocs and nearly 40 PhD students, many of whom hold professorships worldwide; serves in academies, chairs conferences, and advises governments. In public science communication he is articulating the role of sustainable metallurgy and manufacturing in climate change mitigation to policymakers, industry leaders, and the public, countering the misconception that sustainability lies solely in end-use technologies.
With this Professor Raabe shows that in the quest for a sustainable future, the decarbonization and circularization of the metals sector is not optional—it is a prerequisite and Raabe has shaped this quest into a completely new research field. His work shows that this transformation is possible, both through multiple incremental optimization steps in the real industrial world, but particularly through disruptive scientific breakthroughs that unite the disciplines of metallurgy, thermodynamics, engineering, and sustainability science.