Phase-separated and monolithic phenolic aerogels from creosote for solar vapor generation

Solar vapor generation utilizing aerogel evaporators represents a promising paradigm for sustainable freshwater production. Nevertheless, practical deployment is often hindered by fussy fabrication process, requirement of additional absorbers, and inadequate mechanical strength. Herein, a facile method for preparing high strength, phase-separated, and monolithic aerogels for efficient and durable seawater desalination was proposed. By employing creosote—a major fraction of coal tar—as a feedstock, mixed solvents as a phase-separation inducer, and melamine foam as a scaffold, phenolic aerogels (CPAs) were prepared through polymerization and vacuum drying. Unlike conventional counterparts processed with single solvents, the engineered phase-separated CPAs exhibit higher porosity (up to 94.2%) and superior interconnectivity. This architecture not only enhances broadband light absorption and provides expansive evaporation surfaces but also thermodynamically modulates the water state, effectively reducing evaporation enthalpy. Leveraging these synergistic advantages, the optimized CPA evaporator, from an ethanol/n-butanol medium, achieves an evaporation rate of 2.09 kg m−2 h−1 under one sun, with an energy efficiency of 86.3%. Crucially, the evaporator maintains robust performance in hypersaline brine (1.86 kg m−2 h−1 in 20 wt% NaCl) and demonstrates exceptional mechanical strength (4.3 MPa at 90% strain). This work not only provides a scalable route for fabricating phase-separated aerogels but also pioneers a circular economy approach for transforming coal tar waste into high performance desalination materials.