Cementitious core–shell particles with optimized radiative and anti-wetting properties for efficient and durable passive building cooling

Abstract

Developing a building-compatible radiative cooler that exhibits an all-day subambient cooling effect and maintains a clean surface for long-term stability is challenging. This study proposes a liquid marble-derived core–shell particle (LM-CSP) that combines excellent anti-wetting capability, efficient and durable daytime radiative cooling properties, and compatibility with building materials. A series of LM-CSP coated samples were fabricated with varying dosages of BaSO₄ and water-repellent agents, as well as different coating thicknesses. Comprehensive characterization of the as-prepared samples revealed that the optimal LM-CSP exhibited a solar reflectance of 91 % with a mid-infrared emissivity of 0.97 and a water contact angle of ∼151.9° with a roll-off angle of ∼7.8°, respectively. In-depth analyses using XRD, FT-IR, TGA/DTG, and XPS elucidated the underlying mechanisms responsible for the enhanced optical and wetting properties of the LM-CSP. The exceptional durability of the LM-CSP was validated by its subambient cooling effects after being contaminated with muddy slurry (subambient temperature drop of ∼5.4 °C) and after being rain-washed (subambient temperature drop of ∼2.1 °C). EnergyPlus simulations were employed to assess the year-round energy-saving potential of the LM-CSP, and a life-cycle economic and environmental analysis was performed to guide the practical application. The findings of this study are expected to provide new insights into functional cementitious materials with efficient and durable cooling capabilities, ultimately contributing to the advancement of sustainable building design and energy efficiency.