Large-scale industry-compatible sub-ambient radiative cooling pulp
Wenkai Zhu, Yun Zhang, Noor Mohammad, Wenhui Xu, Sefik Tunc, Xiwei Shan, Chenli Zhou, Katherine Semple, Chunping Dai, Tian Li
Abstract
Existing passive daytime radiative cooling (PDRC) materials have promising performance yet are far from mass production and therefore have limited contribution to carbon neutrality. Pulp provides a good opportunity for renewable cooling materials with emerging optical and thermal properties of cellulose to readily deploy for cooling applications. Here, we report a facile yet effective “top-down” approach to transforming industrially bleached pulp into “cooling pulp” with good scalability. The one-step H2O2 spraying improves the cooling pulp’s solar reflection to 89.8%, thereby boosting its PDRC performance. The cooling pulp provides an average 33.2 W m−2 cooling power and a sub-ambient temperature around midday. The cooling pulp’s PDRC effect is demonstrated at a pilot scale of 6.1 × 5.4 m2. Practical applications of cooling-pulp-based products are demonstrated including roofing tiles, heat-sensitive packages, and window visors. Cooling pulp’s economic and environmental benefits make it a cost-competitive and sustainable option for close-to-market cooling technologies.