Biomass-derived porous carbon aerogels for effective solar thermal energy storage and atmospheric water harvesting

Solar-powered hydrated salt-based phase change materials have great potential in the field of solar building energy efficiency. However, hydrated salts suffer from leakage, subcooling and phase separation in practical applications. To address these problems, this study proposes a solution to encapsulate hydrated salt with biomass-derived carbon aerogel as a carrier, which can effectively mitigate the leakage, subcooling, and phase separation problems of hydrated salt without the need of additional modifiers. The composite phase change material exhibited high phase change enthalpy retention (92%), negligible supercooling (0.4 °C), and excellent photothermal conversion efficiency (91.5%). In addition, thanks to the rich porosity and superhydrophilicity of the carbon aerogel, a composite hygroscopic agent combined with lithium chloride was prepared for high-performance atmospheric water harvesting. The composite hygroscopic material has a moisture adsorption capacity of 2.1 g g−1 at 90% RH and can desorb more than 92.3% of the moisture by solar energy drive. The performance was stable after several adsorption-desorption cycles. The multifunctional composites based on biomass-derived carbon aerogels have excellent performance in solar thermal storage and atmospheric water harvesting, providing a new perspective on solar thermal utilization.