Multi‐Functional hBN/ZrO ₂ /CaO – PVDF‐HFP Composite Films for Enhanced Passive Daytime Radiative Cooling and Piezocatalytic Dye Degradation

Abstract Passive daytime radiative cooling (PDRC) is the sustainable cooling solution for climate change mitigation and heat island effects. Present work focuses on developing flexible fiber network to reflect the sunlight and emit infrared energy to reduce cooling loads on roofs. Here, inorganic high bandgap fillers namely, hexagonal boron nitride (hBN), zirconium oxide (ZrO ₂ ), and calcium oxide (CaO) is mixed with dielectric polymer PVDF‐HFP to fabricate single pigment radiative cooling film (SPRC) and multi pigment radiative cooling (MPRC) films by electrospinning method. Developed films with a unique micro/nano porous and cross‐linked structure reflect ≈ 90% of sunlight in solar window (0.2–2.5 µm) and emits 98% of heat in thermal window of atmosphere (2.5–20 µm). During peak solar irradiance, MPRC3 maintains just 1 °C above the ambient temperature (35 °C) and produced maximum cooling power of ≈ 45 Wm ⁻² than other developed films. Further, the ability of dye degradation is examined using piezocatalytic effect and hence, ZrO ₂ mixed SPRC and MPRC films is investigated experimentally. The MPRC4 film has achieve a degradation of 83% owing to improve dielectric properties. Hence, these films are suggested, ideal candidates for building cooling and dye degradation.