Scalable, flame-resistant, superhydrophobic ceramic metafibers for sustainable all-day radiative cooling

Meng Ting Tsai, Sih Wei Chang, Yen Jen Chen, Hsuen Li Chen, Pin Hui Lan, Dai chi Chen, Fu Hsiang Ko, Yu Chieh Lo, Hsueh Cheng Wang, Dehui Wan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Passive daytime radiative cooling (PDRC), as a strategy to dissipate heat through an atmospheric transparency window (ATW) to outer space without any extra energy consumption, has been recently considered as a novel approach for global net-zero emissions. However, limited to expensive manufacturing, poor thermal/chemical stability, or insufficient weather-resistance, the development of a PDRC building material for long-term outdoor usages still remains a challenge. Here, a scalable superhydrophobic silica metafibers (sh-SMF) was fabricated via an electrospinning process combined with the fluorosilane-modification on fiber surface. The optically engineered sh-SMF could attain an extremely high average reflectivity (∼97 %) with near-zero absorption in the solar spectral region, due to the multiple backscattering at the fiber/air interfaces. In addition, the sh-SMF possessed a high average emissivity (∼90 %) in ATW, originated from the strong phonon resonances of the abundant Si-O bonds. Thus, the optimal sh-SMF realized a sub-ambient cooling performance of 6 °C (4 °C in nighttime) and the maximum cooling power of 112 W/m2 (87 W/m2 in nighttime) under a solar irradiance of ∼790 W/m2. Besides, the temperature decline for the sh-SMF-covered building and vehicle models could also achieve 12.7 °C and 17 °C under sunlight, respectively. Noteworthily, the ceramic sh-SMF could withstand high temperatures over 1200 °C, which might effectively prolong the time for resident to evacuate from buildings in fireground situation. Moreover, the superhydrophobic surface (contact angle=155°) of sh-SMF demonstrated attractive self-cleaning and anti-mildew properties. Furthermore, the excellent weather resistance against acid rain and ultraviolet exposure endowed the sh-SMF with long-term cooling performance. Finally, the sh-SMF with above mentioned properties opens a path for future energy-efficient and sustainable architectural applications.

Original languageEnglish
Article number101745
JournalNano Today
Volume48
DOIs
StatePublished - Feb 2023

Keywords

  • Ceramic nanofibers
  • Electrospinning
  • Flame-resistance
  • Passive radiative cooling
  • Self-cleaning

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