In a significant stride towards sustainable cooling solutions, researchers at Nanjing Forestry University have developed an ultrathin and self-cleaning cellulose aerogel film that offers efficient daytime radiative cooling. This innovation, published in the Journal of Bioresources and Bioproducts, addresses the need for alternative cooling technologies that can reduce energy consumption and mitigate global warming.
The study’s background highlights the escalating global demand for cooling energy, which contributes to nearly 20% of a building’s total electricity use. Traditional cooling methods, reliant on fossil fuels, exacerbate global warming, making the development of passive radiative cooling technology an urgent priority.
The researchers aimed to enhance the solar reflectance of cellulose, a material known for its high emissivity in the atmospheric transparency window (8–13 μm), and to create a material with self-cleaning properties. The team employed a freeze-casting and hot-pressing process to develop cellulose nanowhiskers (CNWs) reinforced with zinc oxide (ZnO) to form a composite aerogel film.
The resulting aerogel film, termed CNZ, demonstrated remarkable solar reflectance (97%) and infrared emittance (92.5%), achieving a sub-ambient temperature drop of 6.9 °C under direct sunlight. The film’s unique hierarchical porous structure and chemical bonds (Si-O-C/Si-O-Si) contribute to its high performance. Additionally, the CNZ film exhibited hydrophobicity with a contact angle of 133°, providing an anti-dust function.
The study’s methodology involved a detailed process of preparing the CNZ film, characterizing its morphology, and calculating solar reflectivity and thermal emissivity. The researchers also conducted outdoor radiative cooling tests and evaluated the mechanical performance of the aerogel films.
The results and discussion sections of the study underscore the film’s superior optical performance and mechanical robustness. The CNZ aerogel film’s high solar reflectance and infrared emittance, coupled with its self-cleaning capability, make it a promising material for sustainable thermal regulation and a step towards carbon neutrality.
In conclusion, the Nanjing Forestry University team’s development of the CNW aerogel film represents a significant advancement in eco-friendly cooling solutions. The film’s ability to provide efficient daytime radiative cooling, its mechanical strength, and self-cleaning properties position it as a potential game-changer in the realm of sustainable building materials and energy conservation.
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