Tailoring solid foam structures for high-efficiency photocatalytic filtration of air and water

• Polymer-based solid foams engineered as green bodies for photocatalytic filters. • Foam morphology is tuned by crosslinker concentration and liquid fraction. • SEM imaging reveals exponential pore window distributions. • Permeability spans six orders of magnitude. • Mechanical properties follow classical scaling laws. Solid foams are increasingly recognized for their potential in advanced functional applications, particularly in photocatalytic air and water purification systems. Enhancing their efficiency however requires foams that simultaneously exhibit high permeability and robust mechanical properties—both dictated by the foam’s microstructural morphology, notably the connectivity and distribution of open pores. In direct foaming methods, these characteristics are imparted via a two-step fabrication process involving the formation of a polymeric precursor loaded with inorganic nanoparticles (green body), followed by thermal calcination. Since the final inorganic structure replicates the morphology of the green body, optimizing the precursor is critical. In this work, we investigate the tunability of green body foam architecture by varying key synthesis parameters, including air volumetric fraction and crosslinker concentration. We demonstrate that careful modulation of these variables yields solid foams with tailored porosity and enhanced permeability, while preserving good mechanical properties. These findings offer valuable insights into structure–property relationships in porous solids and support the development of foam-based systems for catalytic and environmental technologies.