Superamphiphobic interface-enhanced inorganic coating for multi-environments tolerant and zero-energy building radiative cooling

Passive radiative cooling (PRC) is a promising technology to achieve eco-friendly building cooling relying on automatic solar reflection and thermal emission. However, sewage, oil and even dust in actual application often cause irreversible damage of surface optical selectivity required by durable cooling. Herein, ZnAl LDO biomimetic microflowers are fabricated as optically selective substrate following by crosslinking of superamphiphobic (SAP) SiO2 nanoparticles to obtain inorganic SAP-PRC coating. Openly-porous micro-nano-structure from LDO microflowers imparts the coating excellent solar reflectivity (∼97.58% normalized with BaSO4) and thermal emissivity (∼98%) as well as efficient resistance for both water (contact angle >158°/slide angle <5°) and oil (contact angle >151°/slide angle <10°). As the result, the coating achieves about 7℃ of cooling effect under (>1400 W/m2) of solar radiation and ∼5℃ lower than the commercial coating. The superamphiphobic surface help SAP-PRC coating avoid over 7.5℃ increase of temperature under >1500 W/m2 after being immersed by oil pollution. It is estimated that the cooling coating can help achieve ∼26% energy saving in hot areas (Haikou in China) throughout a year also considering warming-energy consumption in winter. The synergistic self-cleaning and optical selectivity strategy will effectively promote the commercialization of building PRC materials and further contribute to energy and environment sustainability.