Volcano‐Inspired Dual‐Carbon Network Aerogel for High‐Performance Solar Evaporation With Edge‐Directed Salt Crystallization and Recovery

The escalating global freshwater shortage demands sustainable and energy-efficient desalination solutions. Here, a volcano-inspired dual-carbon-network aerogel (CFCA) that couples hierarchical fluidic channels with multiscale thermal management for high-performance solar desalination is developed. The CFCA features interconnected primary, branching, and microporous conduits within a carbon-black aerogel, reinforced by dispersed short carbon fibers to form continuous capillary pathways for rapid water transport and vapor release. A continuous outer carbon-fiber shell acts as a heat-confining layer and thermal reservoir while directing salt migration toward the edges. The conical geometry generates radial temperature gradients that induce Marangoni convection, enabling spontaneous salt expulsion and edge-localized crystallization without blocking the photothermal surface. Benefiting from these synergistic effects, the CFCA delivers an ultrahigh evaporation rate of 4.08 kg m⁻² h⁻¹ and a solar-to-vapor efficiency of 95.8% under 1 sun. It also maintains an evaporation rate of 2.63 kg m⁻² h⁻¹ in 20 wt.% brine with a salt recovery efficiency of 44.2%, and achieves an average rate of 3.00 kg m⁻² h⁻¹ during seven-day operation in 3.5 wt.% saline water. This work establishes a comprehensive design strategy integrating efficient photothermal conversion, guided mass transport, and recoverable salt crystallization for scalable solar-driven water purification and salt resource recycling.