Solar Absorber Gel: Localized Macro‐Nano Heat Channeling for Efficient Plasmonic Au Nanoflowers Photothermic Vaporization and Triboelectric Generation

Abstract

Plasmonic nanoparticles with outstanding photothermal conversion efficiency are promising for solar vaporization. However, the high cost and the required intense light excitation of noble metals, hinder their practical application. Herein, an inexpensive 3D plasmonic solar absorber gel that embraces all the desirable optical, thermal, and wetting properties for efficient solar vaporization is reported. The broadband absorption and strong near‐field intertip enhancement of the sparsely dispersed gold nanoflowers contribute to efficient light‐to‐heat conversion, while the macro‐nano thermal insulative silica gel retains and channels the plasmonic heat directly to the water pathways contained within the porous gel. The plasmonic‐based solar absorber gel shows a vaporization efficiency of 85% under solar irradiation of 1 sun intensity (1 kW m−2). Moreover, the porous gel framework exhibits high mechanical stability and antifouling properties, potentially useful for polluted/turbid water evaporation. Complementary water condensation‐induced triboelectricity can be harvested alongside fresh water condensate, granting simultaneous fresh water production and electricity generation functionalities. The facile sol‐gel synthesis at room temperature makes the solar absorber gel highly adaptable for practical large‐scale photothermal applications.