Templating synthesis of natural cotton-based hierarchically structured carbon hollow microfibers for high-performance solar vapor generation

Abstract

Solar-thermal desalination by interfacial evaporation that leverages abundant solar energy to convert saline water into clean freshwater has promised an exciting alternative to meet the grand challenges of water scarcity. Among a host of novel materials developed for efficient solar-thermal desalination, carbon-based materials are arguably the most competitive candidates for practical applications due to their superior biocompatibility. However, conventional carbon-based materials have the limitation of an unsatisfactory vapor generation performance under 1 sun illumination. Here, we report a hierarchical carbon nanostructure that is based on rational design of artificial hollow frameworks on natural cotton to achieve very favorable evaporation properties. Hierarchical water pathways of the evaporator rapidly replenish water as it evaporates. Water evaporation is facilitated by a thin-film effect in the hollow frameworks. The hollow carbonized cotton microfibers (HCMFs) evaporated water with an extremely high rate of 3.2 kg m⁻² h⁻¹ under 1 sun illumination, and exhibited outstanding solar desalination performance with excellent stability and durability. This new material design provides a novel approach to solar vapor generation for a broad range of practical applications.