have a very large surface area relative to their volume and exhibit numerous surface defects that further improve the e昀케ciency of conversion. For these analyses, the researchers 昀椀rst produce titanium dioxide nanoparticles by aerosolization and then cover them with gold nanoparticles in a spark gen- erator. The combination of titanium dioxide and gold nanoparticles can extend the useful spectrum from UV to visible light, allowing researchers to initiate the cat- alytic breakdown of CO with sunlight and improve the 2 e昀케ciency. Before reaching the application stage, it will be necessary to characterize the nanoparticles accurately in order to better understand their properties. For such analyses, the Nano Imaging Lab team is a key point of contact when it comes to investigating the morphology Transmission electron microscope image of titanium dioxide (large, light and the ratio of titanium dioxide and gold nanoparticles spots) and gold nanoparticles (small, darker spots). (Image: B. Gfeller, with high-resolution electron microscope images. Department of Environmental Sciences, University of Basel) “Nanoparticles can help to mitigate climate change because their huge surface area and unique defects make them highly e昀케cient catalysts that can convert CO into energy-rich organic compounds 2 such as methane (natural gas) with the help of sunlight.” Benjamin Gfeller, doctoral researcher, Kalberer Group Department of Environmental Sciences, University of Basel X-ray spectroscopy. Titanium dioxide nanoparticles are shown in blue, and gold nanoparticles are shown in green. (Image: B. Gfeller, Depart- ment of Environmental Sciences, University of Basel) Extraction and recovery of raw materials At the Institute for Ecopreneurship at the FHNW School of view to separating and concentrating metals from acidic Life Sciences, former nanoscience student Meret Amrein waste streams. To this end, she produces “layer-by-layer” is researching nano昀椀ltration membranes for the reuse of (LbL) membranes by applying charged polyelectrolyte valuable metals in solar cells in a group led by Dr. Markus layers to a porous support substrate. These membranes Lenz. The recovery of these and other raw materials rep- have high permeability and require signi昀椀cantly lower resents a key step on the journey toward planned climate operating pressures than conventional nano昀椀ltration neutrality with a view to covering supply and demand. membranes — and can therefore be operated with con- Meret Amrein is working in a team that focuses siderably lower power consumption. Overall, this allows on the recycling of next-generation thin-昀椀lm solar cells, for a signi昀椀cant reduction in chemical and energy con- whose production is set to increase over coming years. sumption for the reprocessing of metals from solar cells. These cells often contain metals such as silver and indium. In recycling, metals are usually separated and puri昀椀ed Further nano applications in the environmental using hydrometallurgy (extraction using aqueous solu- sciences tions). This process often consumes huge quantities of Around the world, researchers are investigating many chemicals and is associated with negative environmental other nanotechnology-based approaches in the environ- impacts and health risks. In this context, chemical-free mental sciences. For example, nanotechnology plays a key nano昀椀ltration — a pressure-driven technique for treating role in the monitoring of pollutants, in air quality man- aqueous solutions using pore sizes of less than 2 nanome- agement or in soil treatment. Accordingly, nanosensors ters — can o昀昀er a promising alternative or supplement to are used to monitor various substances in air, water and classical hydrometallurgy. soil. Nanocatalysts and photocatalysis are used to break In her doctoral dissertation, Meret Amrein is in- down airborne pollutants such as nitrogen oxides. In soil vestigating tailor-made nano昀椀ltration membranes with a treatment, iron nanoparticles support the breakdown of SNI INSight December 2024 13