Banana Pseudostem-Inspired Fluidic Photothermal Structure Towards Efficient Solar Steam Generation and Continuous Salt Rejecting

Abstract

Solar-driven steam generation (SSG) is emerging as a promising off-grid strategy to relieve freshwater shortage. In recent years, extensive research works have been conducted to develop full biomass-based SSGs due to their unique hierarchical structural features. However, the long-term durability of biomass-based SSGs remains a concern. Herein, the discarded banana pseudostems have been demonstrated as an excellent potential SSG through a simple surface flame treatment. Firstly, the well-developed pore structure, superior light absorbance, extremely low thermal conductivity and superhydrophilic properties of the surface carbonized banana pseudostem (SCBP) have been well revealed respectively. In addition, it is also demonstrated that the SCBP evaporator can achieve an impressive evaporation rate of up to 2.548 kg∙m-2·h-1 with a 91.96% solar-thermal conversion efficiency superior to most reported biomass based SSGs. Furthermore, a SCBP inspired one-way fluidic photothermal structure is dedicatedly constructed. It is found that the salinity on the top surface of the SCBP evaporator remains far below 26 wt% and the evaporation rate is maintained at 2.384 kg∙m-2·h-1 in a 15 wt% NaCl solution even after 200 hours. Finally, from a proof-of-concept demonstration, the SCBP evaporator also shows an excellent water purification and seawater desalination performance in a real ocean situation.

Keywords: solar-driven steam generation, Biomass, Banana pseudostem, Fluidic photothermal structure, Continuous salt rejecting