Supramolecular Aggregate-Functionalized Biomass Radiative Cooling Aerogel for Building Energy Conservation

Abstract

Biomass aerogels have emerged as promising passive radiant cooling materials, offering a sustainable strategy for mitigating global warming. However, simultaneously achieving high solar reflectance, flame retardancy, and mechanical robustness remains challenging, substantially limiting their deployment in complex environments and long-term energy-saving applications. Here, we report a supramolecular aggregate-functionalized biomass aerogel (AMPx), which integrates effective radiative cooling, fire resistance, and mechanical stability. The aggregate is synthesized through supramolecular self-assembly reactions, using melamine (ME) and phytic acid (PA) as building blocks. By incorporating these aggregates into the sodium alginate matrix and utilizing directional freezing technology, the honeycomb-structured AMPx is prepared. The resulting aerogel exhibits a high solar reflectance of 92% and an atmospheric window emittance of 94%, enabling a temperature reduction of 11.4 °C relative to a commercial aerogel under direct sunlight. Building energy simulations further predict annual cooling-energy savings of up to 54.79%. Moreover, sufficient incorporation of ME-PA aggregates endows AMPx with rapid self-extinguishing properties. Interestingly, incorporating ME-PA aggregates increases the aerogel’s compressive strength and modulus to 3.71 and 12.17 MPa, respectively, representing increases of 334 and 168% compared with the original alginate aerogel. This work proposes a new paradigm for the development of functionally integrated biomass aerogels, demonstrating practical potential for sustainable energy-efficient thermal management.