Photocatalytic cement-based passive cooling composites: The synergy between radiative cooling and self-cleaning mechanisms

Daoru Liu, Jonathan C.O. Zepper, Daiwei Fan, Qingliang Yu (Corresponding author)

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Abstract

Radiative cooling holds promise in combating climate change by reducing energy consumption. However, organic radiative coolers face fabrication complexities, weak environmental reliability, and limited self-cleaning capabilities. To overcome these challenges, we present autoclaved cement pastes, inorganic passive coolers with exceptional energy-free cooling and self-cleaning properties, achieved through a straightforward hydrothermal process. The inorganic cooler incorporating 28 wt% alumina exhibits impressive solar reflectivity (0.91), atmospheric window emissivity (0.91), radiative cooling power (−11.0 W/m2), and effective evaporative cooling (>8 h, 25 W/m2). The high solar reflectivity is attributed to tailored nano/micro particles and pores inducing strong Mie scattering within the solar spectral range (λ = 280–2500 nm). The theoretical cooling properties are validated by the outdoor on-site measurements, and the roles of moisture inside the cooler matrix are verified. Additionally, the cooler formulation featuring 14 wt% nanosilica and 14 wt% alumina demonstrates remarkable self-cleaning capabilities, eliminating approximately 68% of surface contaminants within 30 min. This self-cleaning performance stems from the evolution of C–S–H phases, leading to the formation of massive nano C-(A)-S-H "honeycombs" with "nanowires", enhancing mass adsorption and photocatalytic quantum effects at abundant active sites. This study would open new avenues for scalable, energy-free cement-bound cooling materials for building engineering and align with the UN's sustainable development goals.
Original languageEnglish
Article number108749
Number of pages19
JournalJournal of Building Engineering
Volume85
DOIs
Publication statusPublished - 15 May 2024

Funding

This research is supported by the National Natural Science Foundation of China (Grant No. 52178246 ), China Scholarship Council (No. 202006950045 ), and Eindhoven University of Technology .

FundersFunder number
National Natural Science Foundation of China 52178246
China Scholarship Council 202006950045
Eindhoven University of Technology

    Keywords

    • Atmospheric window
    • Boehmite
    • Hydrogarnet
    • Radiative cooling
    • Self-cleaning
    • Tobermorite

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