Solar-driven vapor generation is one of the most promising techniques for seawater desalination, which has attracted broad attention. However, a significant challenge remains for achieving a low-cost and easy-to-manufacture solardriven steam generation device with higher evaporation efficiency, excellent mechanical performance, and good durability. Herein, a simple and cost-effective method is developed to prepare graphene/cellulose nanocrystals (CNCs) lamella network (GCLN) with melamine foam (MF) as the skeleton. Due to the excellent light absorption properties of graphene and excellent hydrophilic properties of CNCs, GCLN exhibits an evaporation rate of 1.66 kg m-2 h-1 and an evaporation efficiency of 97.5% under 1 kW m-2 of solar radiation. In addition, GCLN can maintain its structural stability and evaporation performance during a series of harsh condition and durability tests. Due to the excellent processability of MF, the 3D-shaped GCLN can be easily designed for an enhanced evaporation rate of 1.59 kg m-2 h-1, which is better than the theoretical limit of the evaporation rate.

The novel design presented in this work offers a new avenue to develop solar steam generation devices for low-cost and large-scale seawater desalination under natural sunlight conditions, which is especially attractive for the urgent fresh water supply in remote areas.