Bioinspired cellulose membrane with hierarchically porous structure for highly efficient solar steam generation

In order to imitate wood truly in structure and content, a viscose solution was used to prepare a cellulose membrane with the hierarchically porous structure of wood by two-step process of ice-templating and low-temperature phase inversion for a solar steam device. The prepared cellulose membrane with microchannels observed by microscopy, which resembled those of wood, showed excellent wicking and water flux characteristics. The physical properties of cellulose membranes, including mechanical and thermal stability, allow their application in many fields. In evaluating of solar steam performance, the water evaporation rate of 1.56 kg m⁻² h⁻¹ from a graphene-coated cellulose membrane at the light density of 1 kW m⁻² exceeded that of a cellulose membrane with pure water. The water evaporation rate of the cellulose membrane was higher than that of a wood-derived solar steam device. The conversion efficiency was increased from 40.72 to 95.57% with modification of the prepared cellulose membrane using graphene. The collected data showed that the cellulose membrane with a hierarchically porous structure was a promising alternative to wood-based solar steam devices, which have the limitations in the reproducibility of structure and composition.