Porous media are all around us! From natural materials like soil, sand and rocks, to everyday products like sponges, filters, diapers, and concrete, these materials contain tiny spaces – or pores – that hold liquids or gases. When you soak up water with a sponge, for example, the pores fill with liquid, pushing out the air. The same process happens underground, where porous rocks store water, oil, or even carbon dioxide. Understanding how fluids move through porous materials is essential for solving real-world problems, such as cleaning up oil spills, improving water filtration, developing better batteries for electric cars, and storing gases underground to fight climate change.

Air pollution is often thought of as an outdoor problem, but the air inside buildings can be just as complex – and sometimes more polluted. Dr Dimitrios Kotzias, former official at the European Commission’s Joint Research Centre, has been exploring how innovative building materials containing semiconductor oxides might actively clean the air we breathe, both outdoors and indoors, using nothing more than light.