Designing an Antibacterial Radiative Cooling Device with the Engineering Optical Properties of Silver Nanoparticles

The integration of radiative cooling and antibacterial functionality into a single-material platform is a promising strategy for addressing the dual global challenges of climate-induced heat stress and microbial contamination risks. An antibacterial radiative cooling device (ARCD) is developed in this study by constructing a triple-layer structure consisting of a top layer of Ag nanoparticles (Ag NPs) for antibacterial action, a polydimethylsiloxane middle layer for mid-infrared thermal emission, and a bottom Ag thin film for visible light reflection. The ligand-exchanged Ag-1,4-butanedithiol (BDT) NPs ensure strong interfacial adhesion and robust antibacterial performance, achieving >99.99% bacterial reduction for both Escherichia coli and Staphylococcus aureus. The optimized ARCD containing 0.1 mg·mL^-1 Ag-BDT NPs exhibits a subambient cooling of up to 3.7 °C under outdoor conditions while maintaining effective antibacterial efficacy. Furthermore, the device is functionalized with nontoxic green-emitting InP quantum dots to enable photoluminescent radiative cooling and aesthetic versatility. The resulting luminescent antibacterial cooling tumbler exhibits real-world applicability with a 6.8 °C reduction in water temperature and sustained antimicrobial activity. This study highlights the potential of multifunctional ARCDs as next-generation materials for sustainable thermal management and hygiene protection in built environments and consumer products.