Batio3@Sio2 Core-Shell Particles Enhanced Pvdf-Hfp Porous Films for Passive Daytime Radiative Cooling

Abstract

Passive Daytime Radiative Cooling (PDRC) has emerged as a sustainable solution to mitigate global warming by enabling energy-free cooling through high solar reflectance and mid-infrared heat emission. PVDF-HFP porous films containing core-shell particles (CSP, BaTiO3@SiO2) were prepared by a phase separation method. CSP enhances solar reflectance by controlled refractive index gradients and Mie scattering. Multistage pores enhanced reflectance (90.7%) through Mie scattering. SiO2 shell layers enhanced infrared emission in the 9.7μm band through the Froehlich resonance and the molecular vibration of PVDF-HFP enhanced the mid-infrared emissivity (95.7%). The indoor xenon simulation showed a temperature drop of 7.2°C, and the outdoor test showed a 10.7°C drop compared to the ambient temperature with a cooling power of 68.7 W/m2. The film is hydrophobic (contact angle of 138°), and after 168 hours of UV aging at 50°C, the reflectivity reduced by only 1.7%, while maintaining hydrophobicity, the contact angle reduced by only 2°. Showing excellent durability which ensure long-term outdoor use.

Keywords: core-shell nanoparticles, Porous films, radiative cooling, Anti-UV aging, Hydrophobicity