Nanoparticle-polymer hybrid dual-layer coating with broadband solar reflection for high-performance daytime passive radiative cooling

Kaixin Lin (Co-first Author), Yuwei Du (Co-first Author), Siru Chen, Luke Chao, Hau Him Lee, Tsz Chung Ho, Yihao Zhu, Yijun Zeng, Aiqiang Pan, Chi Yan Tso*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

34 Citations (Scopus)
39 Downloads (CityUHK Scholars)

Abstract

The passive cooling technology is refrigerant-free and energy-free, making it an appealing alternative to reduce the energy consumption of traditional cooling systems. Although effective in optical design, the materials involving optical structures and metal reflectors are rarely cost-effective or readily applicable. Radiative cooling materials with promising optical properties and good practical applicability remain an urgent research need. We present a simple and scalable method to fabricate a dual-layer nanoparticle-polymer hybrid coating which achieves a high diffused solar reflection of 92.2 % without using metal reflectors, and a strong mid-infrared emission of 95.3 % within the atmospheric window. The coating allows continuous sub-ambient cooling in both daytime and nighttime. Promisingly, the coating reaches about 4 °C lower temperature than ambient under intensive solar irradiation, along with a 78.9 Wm−2 cooling power generation. Moreover, the cooling coating exhibits great reliability and cooling effect when applied as an exterior coating on model houses and the roof of a real building. Applying the proposed material as a roofing material is capable to save cooling energy across various climate zones, especially in the hot climate, which confirms the material's possibility for carbon reduction and tackling global climate change.
Original languageEnglish
Article number112507
JournalEnergy and Buildings
Volume276
Online published23 Sept 2022
DOIs
Publication statusPublished - 1 Dec 2022

Funding

This research is funded by the Hong Kong Research Grant Council via General Research Fund (GRF) accounts 16200518 and 11200121, as well as City University of Hong Kong Applied Research Grant (ARG) via the account of 9667231.

Research Keywords

  • Daytime Passive Radiative Cooling
  • Large-Scale Application
  • Nanoparticle-embedded Polymer Matrix
  • Solar Reflection
  • Thermal Radiation

Publisher's Copyright Statement

  • COPYRIGHT TERMS OF DEPOSITED POSTPRINT FILE: © 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/.

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