Carbon nanofiber stringed hierarchical porous carbon polyhedrons flexible thin films for solar vapor generation

Solar vapor generation shows the great potential to produce clean water from salinity water. Efficient solar absorber plays a key role for high efficient solar vapor generator. Carbon materials have been utilized as solar absorber layer and show promising potentials. In this work, we prepared hierarchical porous carbon membranes (HPCM), comprising carbon nanofiber stringed porous carbon polyhedrons layer anchored on a carbonized filter paper (CFP), from a cellulose nanofiber (CNF) stringed metal organic framework (MOF) (HKUST-1) polyhedrons thin film grown on a filter paper by thermal carbonization. The resulted HPCM with hierarchical porous structures demonstrates different hydrophilicity between the carbon nanofiber stringed porous carbon polyhedrons top layer and bottom CFP layer, which not only ensures enough water supply to surface layer but also prevents excessive bulk water contacting with evaporating surface of higher temperature. When used as solar absorber for solar vapor generation, this HPCM exhibits an optimal water evaporation rate of 1.33 kg m−2 h−1 and solar vapor efficiency of 84.3%. This may provide a facile way to prepare high-performance, low-cost, light weight carbon membranes with flexible and reusability hierarchical porous structure for solar vapor generation.