Large-scale industry-compatible sub-ambient radiative cooling pulp

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.