Robust and Biocompatible Radiative Cooling Textiles Based on a Synergistic TiO2 and SiO2 Nanoparticle Coating

Abstract

Radiative cooling textiles offer a passive strategy for reducing heat load and improving thermal comfort, yet achieving durable coatings with high solar reflectivity and mid-infrared emissivity remains challenging. Here we develop a composite TiO₂ -SiO₂ nanoparticle coating for cotton fabrics, using polyacrylic acid-based functionalization strategy to promote uniform, stable nanoparticle adhesion. Nanoparticle sizes were rationally selected based on Mie-scattering calculations, identifying 200 nm TiO₂ for optimal solar scattering and 50 nm SiO₂ for enhanced emissivity. The resulting coated fabrics exhibited significantly higher reflectance across the solar spectrum and strong emission within the 8-13 µm atmospheric window. Outdoor measurements showed temperature reductions of up to 6.9°C under direct sunlight relative to uncoated cotton, with consistent performance over multiple days. The results are comparable to or exceeding reductions reported in prior nanoparticle-based or photonic textile systems. Cytotoxicity assays of nanoparticle dispersions and fabric extracts confirmed biocompatibility with human dermal fibroblasts, supporting suitability for wearable applications. These findings demonstrate a scalable, durable, and biologically safe radiative-cooling textile with potential for energy-efficient personal thermal management.