An international team of chemistry researchers, led by Dr. Laroussi Chaabane and Prof. Bao-Lian Su, has just demonstrated that it is possible to produce "green" hydrogen using natural water and sunlight. These findings have been published in the prestigious Chemical Engineering Journal.

Faced with climate change, pollution, and energy shortages, the search for alternatives to fossil fuels has become a global priority in order to achieve carbon neutrality by 2050. Among the solutions being considered, green hydrogen appears to be a particularly promising energy carrier: it has a high energy density and can be produced without greenhouse gas emissions. Today, most of the world's hydrogen (around 87 million tons produced in 2020) is obtained through costly and polluting electrochemical processes, mainly used by the chemical industry or fuel cells. Hence the major interest in more sustainable methods.

Producing hydrogen and oxygen directly from water using light, a process known as photocatalysis of water, is often referred to as the "Holy Grail of chemistry" because it is so complex to master. At the University of Namur, researchers at the Laboratory of Inorganic Materials Chemistry (CMI), part of the Nanomaterials Chemistry Unit (UCNANO) and the Namur Institute of Structured Matter (NISM), have taken a decisive step forward. They have demonstrated that it is possible to use natural water, and no longer just ultrapure water, to produce green hydrogen under the action of sunlight.

The new material developed is a three-dimensional (3D) photocatalyst based on titanium oxide, graphene, and gold nanoparticles. This 3D architecture allows for better light absorption and more efficient generation of free electrons, which are essential for triggering the water dissociation reaction. One of the main challenges lies in the use of natural water, which contains minerals, salts, and organic compounds that can disrupt the process. To address this challenge, the researchers tested their device with water from several Belgian rivers: the Meuse, the Sambre, the Scheldt, and the Yser.

The performance achieved is almost equivalent to that measured with pure water.  

This is a first in Belgium, opening up concrete prospects for the sustainable use of local natural resources!

The full article, "Synergistic four physical phenomena in a 3D photocatalyst for unprecedented overall water splitting," is available in open access.

This scientific breakthrough also earned Dr. Laroussi Chaabane the award for best poster at the 4th International Colloids Conference (San Sebastián, Spain, July 2025), highlighting the impact and originality of this work.

An international research team

• University of Namur, Faculty of Sciences, UCNANO, Laboratory of Inorganic Materials Chemistry (CMI) and Namur Institute of Structured Matter (NISM), Belgium | Principal Investigator (PI) | Professor Bao Lian SU; Postdoctoral Researcher | Dr. Laroussi Chaabane
• Institute of Organic Chemistry, Phytochemistry Center, Academy of Sciences, Bulgaria
• Department of Organic Chemistry (MSc), Loyola Academy, India
• Free University of Brussels (ULB) and Flanders Make, Department of Applied Physics and Photonics, Brussels Photonics, Belgium
• University of Quebec in Montreal (UQAM), Department of Chemistry, Montreal, Quebec, Canada
• National Institute for Scientific Research - Energy Materials Telecommunications Center (INRS-EMT), Varennes, Quebec, Canada
• Wuhan University of Technology, National Laboratory for Advanced Technologies in Materials Synthesis and Processing, China

At this stage, the study constitutes proof of concept demonstrating the feasibility of the process. It illustrates the excellence of chemical engineering and nanomaterials research at UNamur, as well as its potential for sustainable energy applications. A new study is underway to evaluate the performance of the process with seawater, a key step towards large-scale green hydrogen production.

The analyses carried out were made possible thanks to the equipment available at UNamur's Physico-Chemical Characterization (PC²), Electron Microscopy, and Material Synthesis, Irradiation, and Analysis (SIAM) technology platforms. UNamur's technology platforms house state-of-the-art equipment and are accessible to the scientific community as well as to industries and companies. 

The authors would like to thank the Wallonia Public Service (SPW) for its ongoing commitment to scientific research and innovation in Wallonia, enabling UNamur to develop technological solutions with a significant societal and environmental impact.

From fundamental to applied research, UNamur demonstrates every day that research is a driver of transformation. Thanks to the commitment of its researchers, the support of its partners from all walks of life, funders, industrial partners, and a solid ecosystem of valorization, UNamur actively participates in shaping a society that is open to the world, more innovative, more responsible, and more sustainable.

Photo: Green speleothems in the Aven du Mont Marcou (Hérault, France) © Stéphane Pire, Gaëtan Rochez (UNamur)

Speleothems, for instance stalactites and stalagmites, are commonly composed of calcite or aragonite (CaCO₃). This mineral compound comes directly from the rock in which the cave was formed and naturally has a white to brownish colour. However, speleothems can sometimes exhibit unique and unusual colours. From yellow to black, blue, red, green, and even purple, there is something for everyone! 

Such a diversity of colours reflects the many possible causes: mineralogical, chemical, biological, or even physical. A speleothem, like any natural formation, is never perfectly pure. Their deposition process, through the precipitation of calcium carbonate dissolved in water, is necessarily accompanied by the deposition of numerous impurities carried along with the water circulating underground. Even if these impurities are sometimes too low in concentration or simply uncoloured, they can still have a visible impact on the colour. 

OK, but what is the point?

The formation of speleothems is very often linked to impurities dissolved in groundwater. Therefore, studying coloured speleothems provides valuable information about potential contamination of surface water with heavy metals or other harmful organic compounds, which in some cases may be consumed by residents. It is therefore a simple and direct way to identify areas with potentially contaminated water and to determine whether this contamination poses an environmental or health risk.

This is the objective of Martin Vlieghe's thesis: to apply a range of cutting-edge analytical techniques to samples of these speleothems to determine these causes and propose an explanation for the origin of the colouring elements. 

Here are a few examples.

An initial project explored the green speleothems of the Aven du Marcou (see photo above). Located in the Hérault department of France, this chasm is well known in the area for its series of impressive shafts, the largest of which is over 100 meters deep. It also has a tiny chamber hidden at the top of a steep wall, which houses an impressive concentration of deep green speleothems. After all the effort of descending and climbing ropes to progress through this very vertical cave, what a wonderful reward to discover this true underground gem! Once the initial wonder has passed, it's time to get to work!  We observe, describe, interpret, and collect a few green fragments from the ground, while respecting the integrity of the site as much as possible. Back in Belgium, it's time to move on to the analyses.

The discovery is all the more surprising given that there are no nickel deposits in the vicinity of the cave! Further study of the composition of the nepouite reveals that they contain a high concentration of zinc, which is also very unusual and suggests that they are in fact quite different from those commonly mined in volcanic deposits. Finally, this mystery was solved by a thorough examination of the rock outcrops in the immediate vicinity of the cave. Just above the cave are siliceous deposits particularly rich in pyrite, an iron sulphide commonly found in this type of settingst. Analysis of these sulphides reveals high concentrations of nickel, which is also found in the natural water source closest to the cave. 

The result of this "investigation" and final explanation: nepouite was able to settle underground through the dissolution of various chemical elements contained in the pyrite of the overlying rocks, which were transported into the cave by surface water and were able to crystallize on site. 

The Malaval cave is very different from the Aven du Marcou. Located in Lozère (France), it extends largely along a high underground river that winds beneath the Cévennes massif. At the bend of a meander, one can find magnificent blue speleothems. 

As in the Aven du Marcou, the coloured speleothems are found only in two specific locations in the cave and nowhere else, suggesting that the origin of the chromophore elements is probably very localized.

Photos - Left: Blue stalagmite in Malaval Cave. Right: Cluster of blue aragonites in Malaval Cave © Gaëtan Rochez (UNamur)

Once again, a few fragments were collected, including a large bluish stalactite found broken on the cave floor. A series of microscopic observations and mineralogical and geochemical analyses were carried out. The first striking finding was that several blue fragments contained no minerals other than aragonite, suggesting that, unlike the green ones from Marcou, it was the aragonite itself that was coloured by the presence of metallic elements. After examining the analyses, three of these elements stood out: copper, commonly cited as the cause of blue colouring in aragonite, as well as zinc and lead. 

While copper appears to be the main cause of the blue colouration, zinc and lead also play a role here. 

Lead also has a marked colouring power, producing green to blue hues, but statistical analysis of coloured and uncoloured areas shows that these colours only appear in the absence of zinc, which seems to inhibit lead-induced colouring. This study clearly demonstrates that, even if a problem seems easy to explain at first glance, it can sometimes hide unexpected subtleties that need to be explored in greater depth in order to uncover all its secrets. 

The Cigalère Cave is one of a kind. Not only does it contain impressive quantities of gypsum, a calcium sulphate found in certain caves, but this gypsum also displays a wide variety of colours rarely seen in nature. Because of this rarity, the cave is particularly well protected, to the point that we were not allowed to collect any fragments from inside it. 

This study was therefore the ideal opportunity to test the Geology Department's new acquisition: a portable X-ray fluorescence spectrometer (pXRF), which allows rapid, in situ, and above all completely non-destructive analysis of coloured speleothems.

Photos - pXRF analysis of a blue stalactite core (left) and a yellow flowstone (right) in the Cigalère Cave © Stéphane Pire (UNamur)

Black is also found in the Chapelle de Donnea, but contrary to what one might think, no iron has been detected. Here, it is manganese in the form of oxides that is responsible for the colouration. This observation is interesting because it clearly demonstrates that black colouration in gypsum, two phenomena that appear similar at first glance, can have very different causes, hence the importance of being able to carry out analyses directly in the field. 

A little further downstream, blue dominates along the main gallery, and analyses have shown strong similarities with the blue speleothems of Malaval, with a marked influence of copper and potentially zinc. 

All this highlights that, despite certain limitations of the device, this type of non-destructive analysis method is a very valuable tool for studying rare, fragile, precious, or protected objects, of which the Cigalère cave is an excellent example! 

Martin Vlieghe's doctoral thesis on "The origin(s) of colored speleothems in caves," supervised by Professor Johan Yans and in collaboration with Gaëtan Rochez, began in February 2022. All three researchers are members of the Faculty of Sciences, Department of Geology at UNamur and the ILEE Research Institute. 

ILEE (Institute of Life, Earth and Environment) is directly involved in issues related to the study and preservation of the environment, to which this subject is directly linked. 

The various analyses were carried out with the support of UNamur's technological platforms:

• Physicochemical characterization (PC²)
• Lasers, optics, and spectroscopy (LOS)
• Electron microscopy
• Synthesis, Irradiation and Analysis of Materials (SIAM)

Some analyses were carried out in partnership with KUL, MRScNB and UMontpellier, and access to the caves was provided by the Association Mont Marcou, the Malaval Association and the Association de Recherche souterraine du Haut Lez.

This thesis was originally funded by the ILEE institute and institutional funds from UNamur, and by an Aspirant F.R.S. - FNRS grant (FC 50205) since October 2023.

It is also closely linked to the new research partnership supported by the RELIEF network (Réseau d’Échanges et de Liaisons entre Institutions d’Enseignement supérieur Francophones), the ILEE research institute at UNamur, and EDYTEM (Environnements, Dynamiques et Territoires de Montagne, Université Savoie Mont Blanc).  Mobility programs between these entities will strengthen a common research area: the study of the critical zone, the most superficial zone of the Earth, where rocks, water, air, and living organisms interact. The perspective is to develop other transdisciplinary research areas and potential teaching projects in the field of environmental sciences and sustainable development.

Studying geology means developing a solid foundation in physics, chemistry, and biology in order to understand the Earth, from its internal dynamics to surface processes and their interactions with our environment and human activities. 

Thanks to their interdisciplinary training, geologists are ideally positioned to perform a variety of roles that require a rigorous scientific approach to solving complex problems (research and development, project management, consulting, and education).

What are the advantages of studying at UNamur? 

• Practical training and numerous field activities
• Strong scientific foundations
• Immersion in geology from block 1
• The possibility of ERASMUS from block 3 onwards
• Close contact with teachers

This article is taken from the "Issues" section of Omalius magazine #40 (March 2026).

“August 6, 1945, was Day Zero. The day it was demonstrated that universal history might not continue, that we are in any case capable of severing its thread—that day ushered in a new age in world history,” wrote Günter Anders, considered the first “philosopher of the bomb,” in *Hiroshima Is Everywhere* (1982). 

For many thinkers, the invention of the atomic bomb and its use against Japan by the United States constitute a turning point in the destiny of humanity. The Chernobyl accident in 1986—40 years ago this April—and the Fukushima disaster in 2011, whose 15th anniversary was recently marked, are two other landmark events, serving as a reminder of the potential dangers of nuclear energy. 

“Günter Anders also speaks of ‘globocide,’ that is, the possibility that emerged with nuclear technology to ‘make everything disappear,’” explains Danielle Leenaerts, a researcher in art history at UNamur.  “He also emphasizes the impossibility of separating the risks of military nuclear power from those of civilian nuclear power, since radioactive fallout is a possibility in both areas.” 

Today, however, nuclear energy is ubiquitous in our lives. Every day, for example, many workers are exposed to ionizing radiation. In Belgium, anyone professionally exposed to such radiation must wear a dosimeter at chest level (Article 30.6 of the Royal Decree of July 20, 2001). This data is then centralized, analyzed, and archived monthly by the AFCN (Federal Agency for Nuclear Control). An epidemiologist, researcher at the Faculty of Medicine, and member of the Namur Research Institute for Life Sciences (NARILIS) at UNamur, Médéa Locquet is also a member of the Belgian delegation to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), whose mission is to assess the levels and effects of exposure to ionizing radiation on human health and the environment. In this context, she studies in particular the effects of occupational exposure—whether among airline pilots exposed to cosmic rays, uranium mine workers, or healthcare personnel—as well as environmental exposure, and notably the impact of radon, 

“a naturally occurring radioactive gas emitted by the soil that can accumulate in buildings, and which is now the second leading cause of lung cancer after tobacco,” she notes. 

As part of her collaboration with UNSCEAR, Médéa Locquet is participating with her colleagues in Japan in the “Lifespan Study,” which investigates the consequences of the bombings of Hiroshima and Nagasaki on irradiated survivors and their descendants. While the dangers of acute exposure to ionizing radiation (so-called “deterministic” effects) are well understood, the effects of low-dose exposure (“stochastic effects”) remain more complex to understand and assess. 

“Generally, in medicine, we move from basic research to applied research. Here, it’s the opposite: by observing an application of military nuclear technology, we directly study the effects on human beings to establish radiation protection standards and confirm certain mechanisms of action of ionizing radiation by returning to experimental research,” explains the researcher. 

Cancer cells are, in fact, characterized by their ability to proliferate continuously. 

Radiotherapy traditionally uses an X-ray beam to target the tumor, but today, researchers are increasingly turning their attention to protons. 

“UNamur has the only proton irradiator in the Wallonia-Brussels Federation, which allows us to study their advantages over X-rays,” notes Carine Michiels. 

Read our previous article on this topic: ALTAïS – Penetrating the depths of matter to address current challenges

“Protons have a ballistic advantage,” explains Anne-Catherine Heuskin. “When you target a tumor with X-rays, some of the radiation is absorbed and some passes through to the other side. By irradiating upstream, you also affect the downstream area. But the goal is to spare healthy tissue as much as possible: in breast cancer, for example, we try to avoid irradiating the heart.” 

Because they interact differently with matter, protons deposit a small amount of energy continuously as they travel. 

“On the other hand, when they have only a few centimeters or millimeters left to travel, they release all their energy at once,” continues Anne-Catherine Heuskin. “Whatever lies downstream is then spared.” 

Proton therapy is particularly promising for treating pediatric cancers—that is, for patients who still have a very long life expectancy and are therefore at greater risk of experiencing the long-term effects of radiation on their healthy tissues. 

In addition to these external radiation therapy techniques, it is also possible to treat tumors using internal radiation therapy, 

“by attaching a radioactive atom to a ‘carrier,’ such as gold nanoparticles, which will transport this atom to the tumor via the bloodstream,” explains Carine Michiels. 

This technique maximizes the effect on cancer cells while sparing normal cells as much as possible. 

“Over the past 5 to 10 years, the major breakthrough in cancer treatment has been immunotherapy,” she continues. “But we still don’t understand why some patients respond to it and others don’t. One hypothesis is that we need to boost the cancer cells so that they are recognized by the immune system. And this is where radiation therapy has a huge role to play, because by damaging the cancer cells, it helps boost the immune response. The combination of radiation therapy and immunotherapy is therefore set to play a leading role.” 

Today, the scientific community is increasingly concerned about the long-term risks (cancer, leukemia, etc.) associated with medical exposure to radiation. 

“Several recent studies highlight an increased risk of brain cancers and leukemias in patients who underwent repeated CT scans during childhood,” explains Médéa Locquet. “During childhood, the high rate of cell proliferation and differentiation makes cells more radiosensitive, which increases the risk of late effects, particularly in adulthood.” 

Similarly, radiation therapy treatment can increase the risk of certain diseases, even though these risks are now well understood and generally well managed. 

“My research hypothesis,” says Médéa Locquet, “is that the effects of exposure to ionizing radiation mimic the aging process, since what we will find are mainly complications such as cancer, cardiovascular diseases, as well as endocrine or neurodegenerative disorders—that is, diseases that appear in the general population with advancing age. Confirming this hypothesis would allow us to optimize doses to prevent this accelerated aging and the onset of treatment-related late effects. We could also try to prevent it by using senomorphs (editor’s note: agents that block the harmful effects of senescent cells), as well as through physical activity and nutrition programs in post-cancer care.”

What is nuclear energy?

Nuclear energy is a form of energy released by the nucleus of atoms, which is composed of protons and neutrons. It can be produced by fission (the splitting of an atomic nucleus into several parts) or by the fusion of several nuclei. The nuclear energy used today to generate electricity comes from nuclear fission. Energy production through fusion (as occurs in the cores of the sun and stars) is still in the research and development phase.

How does nuclear fission work?

In nuclear fission, an atom’s nucleus splits into several smaller nuclei, thereby releasing energy through a chain reaction. For example, when a neutron strikes the nucleus of a uranium-235 atom, it splits into two smaller nuclei and two or three neutrons. These neutrons then strike other uranium-235 atoms, which in turn split, producing more neutrons, with a multiplier effect that releases energy in the form of heat and radiation. 

What are the applications of nuclear energy?

Since the discovery of radioactivity, the properties of nuclear energy have been used in numerous applications, notably in nuclear weapons, as well as in military ships and submarines. But nuclear energy also has numerous applications in research, medicine, industry, the food industry (combating insect pests and pathogenic microorganisms), and even archaeology and museology (dating and authenticating certain artifacts).

This is particularly evident in the work of Belgian artist Cécile Massart, who explores landfills as sites of memory, and that of photographer Jacqueline Salmon, who documented the decommissioning of the Superphenix power plant (Isère), “offering a form of knowledge” that is distinct from and complementary to that of scientists. Both are featured in the exhibition curated by Danielle Leenaerts at the Delta, *(Faire) face au nucléaire*, and in her eponymous book (published by La Lettre Volée).

I was fascinated by the research field of one of my professors, Guy Demortier. He was working on the characterization of antique jewelry. He had found a way to differentiate by PIXE (Proton Induced X-ray Emission) analysis between antique and modern brazes that contained Cadmium, the presence of this element in antique jewelry being controversial at the time. He was interested in ancient soldering methods in general, and the granulation technique in particular. He studied them at the Laboratoire d'Analyses par Réaction Nucléaires (LARN). Brazing is an assembly operation involving the fusion of a filler metal (e.g. copper- or silver-based) without melting the base metal. This phenomenon allows a liquid metal to penetrate first by capillary action and then by diffusion at the interface of the metals to be joined, making the junction permanent after solidification. Among the jewels of antiquity, we find brazes made with incredible precision, the ancient techniques are fascinating.

In fact, this was one of Namur's fields of research at the time: heritage sciences. Professor Demortier was conducting studies on a variety of jewels, but those made by the Etruscans using the so-called granulation technique, which first appeared in Eturia in the 8th century BC, are particularly incredible. It consists of depositing hundreds of tiny gold granules, up to two-tenths of a millimeter in diameter, on the surface to be decorated, and then soldering them onto the jewel without altering its fineness. So I also trained in brazing techniques and physical metallurgy.

I applied for a position as a physicist at CERN in the field of vacuum and thin films, but was invited for the position of head of the vacuum brazing department. This department is very important for CERN as it studies methods for assembling particularly delicate and precise parts for accelerators. It also manufactures prototypes and often one-off parts. Broadly speaking, vacuum brazing is the same technique as the one we study at Namur, except that it is carried out in a vacuum chamber. This means no oxidation, perfect wetting of the brazing alloys on the parts to be assembled, and very precise temperature control to obtain very precise assemblies (we're talking microns!). I'd never heard of vacuum brazing, but my experience of Etruscan brazing, metallurgy and my background in applied physics as taught at Namur were of particular interest to the selection committee. They hired me right away!

CERN is primarily known for hosting particle accelerators, including the famous LHC (Large Hadron Collider), a 27 km circumference accelerator buried some 100 m underground, which accelerates particles to 99.9999991% of the speed of light! CERN's research focuses on technology and innovation in many fields: nuclear physics, cosmic rays and cloud formation, antimatter research, the search for rare phenomena (such as the Higgs boson) and a contribution to neutrino research. It is also the birthplace of the World Wide Web (WWW). There are also projects in healthcare, medicine and partnerships with industry.

For my part, in addition to developing vacuum brazing methods, a field in which I've worked for over 20 years, I've worked a lot in parallel for the CLOUD experiment. For over 10 years, and until recently, I was its Technical Coordinator. CLOUD is a small but fascinating experiment at CERN which studies cloud formation and uses a particle beam to reproduce atomic bombardment in the laboratory in the manner of galactic radiation in our atmosphere. Using an ultra-clean 26 m³ cloud chamber, precise gas injection systems, electric fields, UV light systems and multiple detectors, we reproduce and study the Earth's atmosphere to understand whether galactic rays can indeed influence climate. This experiment calls on various fields of applied physics, and my background at UNamur has helped me once again.

I was also responsible for CERN's MACHINA project -Movable Accelerator for Cultural Heritage In situ Non-destructive Analysis - carried out in collaboration with the Istituto Nazionale di Fisica Nucleare (INFN), Florence section - Italy. Together, we have created the first portable proton accelerator for in-situ, non-destructive analysis in heritage science. MACHINA is soon to be used at the OPD (Opificio delle Pietre Dure), one of the oldest and most prestigious art restoration centers, also in Florence. The accelerator is also destined to travel to other museums or restoration centers.

ELISA uses the same accelerator cavity as MACHINA. The public can observe a proton beam extracted just a few centimetres from their eyes. Demonstrations are organized to show various physical phenomena, such as light production in gases or beam deflection with dipoles or quadrupoles, for example. The PIXE analysis method is also presented. ELISA is also a high-performance accelerator that we use for research projects in the field of heritage and others such as thin films, which are used extensively at CERN. The special feature is that the scientists who come to work with us do so in front of the public!

I remember that in 1989, I finished typing my report for my IRSIA fellowship in the middle of the night, the day before the deadline. It had to be in by midnight the next day. There were very few computers back then, so I typed my report at the last minute on one of the secretaries' Macs. One false move and pow! all my data was gone - big panic! The next day, the secretary helped me restore my file, we printed out the document and I dropped it straight into the mailbox in Brussels, where I arrived after 11pm, in extremis, because at midnight, someone had come to close the mailbox. Fortunately, technology has come a long way since then...

The proximity between teaching and research inspires and questions. This enables graduate students to move into multiple areas of working life.

Come and study in Namur!

Serge Mathot (May 2025) - Interview by Karin Derochette

• The CERN accelerators complex
• The Science Portal, CERN's public education and communication center
• Newsroom - June 2025 | The Departement of physics hosts a delegation from CERN
• Newsroom and Omalius Alumni article - September 2022 | François Briard