Biomimetic surface strategy of spectrum-tailored liquid metal via blackbody inspiration for highly efficient solar steam generation, desalination, and electricity generation

Highlights: • Spectrum-tailoring of liquid metal via dipole layer mechanism. • Sunflower-inspired strategy for structured blackbody with sunlight reflections. • Binary configurations of surface topography and interior topology for aerogel. • Synergistic mechanism of dipole layer and blackbody for multiple applications. Solar steam generation as a promising strategy has attracted more and more attention owing to its applications of the water purification which meet the demand of clean water worldwide. Photothermal material, as the key component of solar evaporators, has aroused great interest in the design of extraordinary photothermal conversion efficiency. Herein, liquid metal was the first time used to develop a photothermal promotor with the tailored spectrum via the dipole layer strategy for highly efficient solar steam generation. As the proof-of-concept, cellulose nanocrystals were applied as bonding agent of matrix scaffold and photothermal layer for the successful preparation of the lignin-based aerogel evaporators. Inspired by the seedless sunflower, binary configurations of interior topology and surface topography was manipulated on the layer-doubled lignin-based aerogels with inverted pyramid veneer for the favorable multi-functionalities, which could hardly realize within the entirety before. The blackbody-inspired aerogel evaporators showed exceptional solar evaporation efficiency of 94% under 1 sun, and the depuration and desalination efficiency up to 99% in the sewage (water containing Zn²⁺, Ni²⁺, Cu²⁺, Fe³⁺) and seawater (Yellow sea, China). In addition, the resulted lignin-based aerogels also presented a promising application in the electricity generation field. This work opens a new avenue to design liquid metals with excellent light absorption ability for the effective solar steam generation, sewage depuration and desalination, with the application of liquid metals in the electricity generation field.