A simple, natural 3D honeycomb structure achieving high photothermal conversion and sustainable salt-resistance for efficient desalination and potential electricity generation

Excellent light absorption and suppressed salt crystallization are required for solar evaporators to operate continuously and efficiently. Herein, we report a waste biomass-derived solar evaporator (Le/CNTs-corn stalk) with natural 3D honeycomb structure and sustainable salt-resistance for efficient desalination and potential electricity generation. This simply fabricated 3D light-absorbing nanostructure greatly increases the light transmission distance, achieving significant boost in light absorption of 94.8 % and photothermal conversion efficiency of 92.5 %. Moreover, a spontaneous salt exchange capability between vascular bundles and laser engraved channels is developed according to the Hagen-Poiseuille's law. Salt concentration difference formed by the volume flowrate is alleviated to facilitate salt dissolution and prevent salt accumulation on the surface, enabling to evaporate effectively for 8 h even in 10 % salt solutions. In addition, tentatively inserted carbon nanotubes on its internal channel surface raises the total zeta potential and causes surface negative charge. A promising electricity generation potential is explored with continually generating a steady voltage of ∼136 mV. Our work provides a sustainable and massive strategy to realize efficient water production and simultaneous electricity generation using sufficient solar energy and biomass resources.