Novel technique shines light on next-gen nanomaterials: how MXenes truly work
© Ralfy Kenaz/Hebrew University, Andreas Furchner/HZB
Researchers have for the first time measured the true properties of individual MXene flakes — an exciting new nanomaterial with potential for better batteries, flexible electronics, and clean energy devices. By using a novel light-based technique called spectroscopic micro-ellipsometry, they discovered how MXenes behave at the single-flake level, revealing changes in conductivity and optical response that were previously hidden when studying only stacked layers. This breakthrough provides the fundamental knowledge and tools needed to design smarter, more efficient technologies powered by MXenes.
Scientists have made a breakthrough in understanding the fundamental intrinsic properties of MXenes — a class of materials hailed for their promise in next-generation energy storage and advanced electronics.
MXenes (pronounced max-eens) are ultra-thin materials only a few atoms thick, celebrated for their ability to conduct electricity, store energy, and interact with light. Until now, however, most studies examined MXenes in bulk form — as thin films made up of many overlapping flakes. That approach, while useful, masked the unique properties of single flakes, leaving unanswered questions about their true potential.
The new study was led by Dr. Andreas Furchner from Helmholtz-Zentrum Berlin (HZB), together with Dr. Ralfy Kenaz from the Hebrew University’s (HUJI’s) Institute of Physics — a strong collaboration between the research groups of Dr. Tristan Petit and Prof. Ronen Rapaport, respectively. It reveals, for the first time, how individual MXene flakes behave when isolated and studied at the nanoscale. The findings were recently published in ACS Nano, one of the world’s leading nanoscience and nanotechnology journals.
Ellipsometry is one of the most advanced non-invasive optical techniques for material characterization. However, conventional ellipsometers inherently struggle to measure areas smaller than 50 microns — roughly the width of a human hair — making them unsuitable for analyzing the microscopic structures common in modern technology and research. As a result, ellipsometry measurements on MXenes have been limited to macroscopic thin films made of stacked, overlapping flakes. This limitation has prevented direct measurements of individual MXene flakes, whose lateral dimensions are much smaller, thereby hindering a true understanding of their intrinsic properties.
To crack the problem, the researchers employed an advanced, patented technique they developed and call spectroscopic micro-ellipsometry (SME) — essentially a kind of “optical fingerprinting” — which allowed them to measure the optical, structural, and electronic properties of single MXene flakes with high lateral resolution and without damaging them. In the study, individual MXene flakes of varying thicknesses were synthesized in HZB and sent to HUJI for SME measurements. Complementary nanoscale measurements were performed at HUJI’s Nano Center, and all data analyses were carried out collaboratively by both groups.
By shining light with defined polarization states on microscopic flakes as thin as a single molecular layer and analyzing how that light reflected back, the researchers mapped how the material’s ability to conduct electricity and interact with light changes depending on thickness and structural properties. They discovered that as MXene flakes become thinner, their electrical resistance increases — a critical insight for building reliable, high-performance devices.
The method was so precise that it matched nanoscale imaging tools like atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM), confirming its power as a non-invasive diagnostic tool.
Dr. Furchner of Helmholtz-Zentrum Berlin, who brought his extensive expertise in ellipsometry to the MXene field, noted:
“Measuring how single MXene flakes depolarize light enabled us to pinpoint structural intra-flake variations in thickness at the nano level. We were excited to see how well the results match destructive techniques like STEM.”
Dr. Kenaz of Hebrew University, developer and co-inventor of the SME technique, said:
“What is truly outstanding with this work is that in less than one minute, we can directly measure the optical properties, thickness, structural properties, and conductivity of individual MXene flakes — all in a non-destructive way. Normally, these measurements require three different instruments, are time-consuming and destructive, and in the end, not as reliable as spectroscopic micro-ellipsometry.”
Dr. Petit of Helmholtz-Zentrum Berlin added:
“This opens new fields of research for operando characterization, which were previously only possible with synchrotron techniques such as STXM (Scanning Transmission X-ray Microscopy). We now have a novel, high-throughput technique to understand how MXenes evolve in different environments — a lab-based tool that complements X-ray imaging experiments, for example.”
MXenes are being explored for a wide range of applications — from ultrafast batteries and water purification systems to flexible electronics and solar energy harvesting. Understanding how the material behaves at the single-flake level is essential for designing devices that are both efficient and scalable.
Prof. Rapaport of Hebrew University added:
“This work provides a roadmap for integrating MXenes into real technologies by offering a direct view of their intrinsic properties, without the interference of stacked layers or impurities. By refining how we study these materials using our SME technique, we are paving the way for their use in optoelectronic devices, energy solutions, and beyond.”
The study not only unlocks fundamental knowledge about MXenes but also establishes spectroscopic micro-ellipsometry as a new standard for analyzing 2D materials. With this breakthrough, scientists worldwide may soon gain the ability to probe other emerging nanomaterials in the same way.
As Dr. Petit of Helmholtz-Zentrum Berlin concluded:
“This is a powerful demonstration of how international collaboration and advanced physics can accelerate materials science. MXenes are just the beginning.”
- Susanne Nies appointed to EU advisory group on Green DealDr. Susanne Nies heads the Green Deal Ukraina project at HZB, which aims to support the development of a sustainable energy system in Ukraine. The energy expert has now also been appointed to the European Commission's scientific advisory group to comment on regulatory burdens in connection with the net-zero target (DG GROW).
- The future of corals – what X-rays can tell usThis summer, it was all over the media. Driven by the climate crisis, the oceans have now also passed a critical point, the absorption of CO2 is making the oceans increasingly acidic. The shells of certain sea snails are already showing the first signs of damage. But also the skeleton structures of coral reefs are deteriorating in more acidic conditions. This is especially concerning given that corals are already suffering from marine heatwaves and pollution, which are leading to bleaching and finally to the death of entire reefs worldwide. But how exactly does ocean acidification affect reef structures?
Prof. Dr. Tali Mass, a marine biologist from the University of Haifa, Israel, is an expert on stony corals. Together with Prof. Dr. Paul Zaslansky, X-ray imaging expert from Charité Berlin, she investigated at BESSY II the skeleton formation in baby corals, raised under different pH conditions. Antonia Rötger spoke online with the two experts about the results of their recent study and the future of coral reefs.
- Long-term stability for perovskite solar cells: a big step forwardPerovskite solar cells are inexpensive to produce and generate a high amount of electric power per surface area. However, they are not yet stable enough, losing efficiency more rapidly than the silicon market standard. Now, an international team led by Prof. Dr. Antonio Abate has dramatically increased their stability by applying a novel coating to the interface between the surface of the perovskite and the top contact layer. This has even boosted efficiency to almost 27%, which represents the state-of-the-art. After 1,200 hours of continuous operation under standard illumination, no decrease in efficiency was observed. The study involved research teams from China, Italy, Switzerland and Germany and has been published in Nature Photonics.