07/12/2024 | Research, Research, English

Materials of the future

Chemistry develops new materials that are durable, functional and sustainable

The future is all about renewable energy. But that’s not all that needs to change. The Institute of Inorganic and Materials Chemistry develops new materials that are durable, functional and at the same time sustainable.

By Eva Schissler

Sanjay Mathur was President of the American Ceramic Society from 2022 to 2023. He is one of the initiators of the global scientific network ‘International Alliance of Societies for a Sustainable Future’.

Every year, the day when human consumption exceeds the resources that the earth naturally provides falls on an earlier date than in the past. While in the 1970s it was still in December or November, the so-called ›Earth Overshoot Day‹ will be reached at the end of July or beginning of August this year.
The energy transition is intended to reverse this trend – in Germany and around the world. However, as the world’s population grows and prosperity increases, so does the global consumption of goods, which constantly drives up the demand for energy. That makes it unclear how quickly the world can move away from climate-damaging fossil fuels.

Professor Dr Sanjay Mathur sees the energy issue as a crucial cornerstone on the road to a sustainable future. This is why he and his team are researching efficient electrolysis methods and innovative catalysts to produce green hydrogen. But since the production of new goods requires more and more input, the materials used by industry also need to change: They have to become more durable and the amount of material required must be reduced. Mathur is convinced: »The sustainability transition is a materials transition.«

Mathur holds the Chair of Inorganic and Materials Chemistry at the Department of Chemistry and Biochemistry of the Faculty of Mathematics and Natural Sciences. In his research in the field of chemical nanotechnologies, he has focused for many years on how to improve the functionality of materials, increase their longevity and reduce resource input.

He also sees a need for improvement in technologies that are particularly important for the energy transition: »If we look at wind power, for example, today the systems are only built to function for around twenty years. The same applies to materials for battery and photovoltaic systems. They require a holistic concept – from the integration of the materials into the components to their optimal utilization and reuse.« Mathur’s team conducts research on batteries for electric cars that can be recharged with integrated solar panels, or materials for fuel cells that utilize hydrogen as an energy source. He’s not alone with his interest in these aspects of material development – his team comprises 45 people from 17 countries.

Longevity without ›forever chemicals‹

Substituting established material technologies is no trivial matter for Mathur: »This means a disruptive change for many industries,« explained the chemist. One example is the restrictions associated with the future use of per- and polyfluorinated alkyl substances (PFAS), the so-called ›forever chemicals‹. Most PFAS may no longer be used in the European Union in future, as their strong chemical compounds are not naturally degradable and harmful to the environment. However, he believes there is an urgent need to use these versatile materials with unique properties. In addition to non-stick pans and functional clothing, they are used in the semiconductor and automotive industries as well as other high-tech sectors.

An electroloysis instrument producing green hydrogen that draws its energy from integrated solar panels.

Mathur and his team develop extremely water-repellent surface coatings for industrial applications.

Much of the research in the inorganic chemistry laboratories at the university takes place with partners from industry, including the South Korean car manufacturer Hyundai and the German glass manufacturer Schott AG. However, the PFAS restriction came into force just before the conclusion of a joint project with Hyundai. The team regarded the restriction as an opportunity to refocus: »Chemical materials in industry were always supposed to be optimized for durability. PFAS have fulfilled this requirement very well, but now we have to look for less problematic alternatives,« said Mathur.

Since then, the chemists have been working on new substances. In the automotive industry, for example, highly water-repellent – or superhydrophobic – functional coatings can improve the corrosion protection of components. The challenge is to create a surface with a very thin layer of such a material, so that the carrier material underneath can be produced more cheaply and with less material.

His group works on nanostructuring. It meets both sustainability requirements of durability and reduced material use. »Nanoparticles can change the properties of a surface and fulfil various other functions,« said the chemist. For example, his group is developing magnetic nanoparticles that are equipped with a specific enzyme. Unfortunately, this technology does not work to break down PFAS in nature, but it can be used to break down microplastics in waters or sewage plants.

Delivering drugs into cells

Similar to forever chemicals, nanoparticles also have a bad reputation. They are considered harmful to our health because their extremely small size allows them to enter our cells. However, all substances that are not found in living matter are potentially toxic. For Mathur, there is no proof that the smaller they are, the more harmful they will be. They only harm the body if they disrupt cellular processes or upset the energy balance. But it is still unclear whether this is the case.

Instead, Mathur sees very useful applications for nanoparticles, particularly in medicine: Nanocarrier substances for drugs could mean that significantly fewer active ingredients are needed to achieve the desired therapeutic effect. When conventional carrier materials are used, a large proportion of the medication is excreted directly from the body. »We could encapsulate the active ingredient in nanoparticles so that it is only released where we need it.« The release would also be delayed. It may not be necessary to use several milligrams of an active ingredient, but only a few to achieve the same efficacy.

In the joint research project ›Transformative Nanocarriers for RNA Transport and Tracking‹, supported by the University of Cologne’s funding line ›UoC Forum‹, Mathur’s team is collaborating with colleagues from the Faculty of Medicine and RWTH Aachen University. The project focuses on how cancer drugs can reach their target more effectively and how an intelligent drug release mechanism can be implemented in the microenvironment of a tumour. »With the conventional administration of drugs, more than 99 per cent of an active ingredient passes through the body and can also be absorbed by healthy organs – an undesired side effect,« said Mathur. This so-called ›systemic toxicity‹ causes side effects of chemotherapy such as premature ageing of the skin or hair loss. The targeted delivery of an active substance solely into the affected cells with the aid of nanoparticles could reduce such side effects.

A house that lives

Sanjay Mathur’s speciality is actually functional ceramics, which play a key role in both the energy transition and in medicine. In this field, he also collaborates with medical partners in Cologne, Bonn and Aachen, for example to develop even more durable medical implants such as hip prostheses or vascular stents. But this is not the only way to utilize this group of materials. Another example is a special building material into which vertical gardens can be integrated. Together with the German Federal Institute for Materials Research and Testing, a working group at Mathur’s department is developing inorganic particles that contain plant nutrients from which plants can grow directly. These functional ceramics are applied as a thin layer on cement and provide the plants with all the necessary nutrients and moisture. This means that green façades can not only bind CO2, but also fine dust from the air. With progressing climate change, buildings with this material could provide cooling in very hot countries.

Like in these samples, plants could grow directly out of building structures in the future.

There is even a whole new term for this type of building material: ›engineered living materials‹. They go one step further than façade greening, integrating the plant material directly into the core structure. »The choice of materials is particularly important as the stability and safety of the building must not be compromised,« said Mathur.

These examples are just a few of the many research areas in which students, doctoral candidates and postdocs are working at the Institute of Inorganic and Materials Chemistry. What now falls under ›sustainability‹ has been on the agenda there for much longer. Sanjay Mathur is pleased that the university has recently created a Vice-Rectorate for Sustainability and a Sustainability Office, which tie in with many of his research topics.

However, the University of Cologne does not have engineering sciences, so there are no opportunities to test the many application-oriented research results from Mathur’s labs and to help with their technical implementation. This is where he relies on the strong regional research network: In addition to partners from industry, Mathur’s group cooperates, among others, with RWTH Aachen University, the German Aerospace Center, Forschungszentrum Jülich and the University of Bonn. He is also in close contact with the Gateway Excellence Start-up Center. »We make many patent-worthy discoveries. The Gateway technology scouts talk to all of our working groups and advise us.« Already ten years ago, the Materials Alliance Cologne was founded and has been promoting cooperation between the university and private industry ever since.

A profile for Cologne’s chemistry

For Sanjay Mathur, the wide range of topics taught and researched at the Department of Chemistry and Biochemistry is a great asset. But he also sees advantages in a more targeted profile development, for example through the acquisition of a Collaborative Research Centre funded by the German Research Foundation or other prestigious funding: »With such a grant, we could strengthen our position in the research landscape, create more efficient structures for the promotion of early-career scientists and optimize our teaching.«

In any case, he considers Cologne to be the ideal location for such a project: In addition to many industrial companies, the universities and research institutes in the so-called ABCD-J region (Aachen, Bonn, Cologne, Düsseldorf and Jülich) cooperate closely in many areas. Together with these partners, the chemist wants to continue developing materials and energy sources for a future in which there is no Earth Overshoot Day.

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