Morphology Control of Ag Polyhedron Nanoparticles for Cost-Effective and Fast Solar Steam Generation

Since introduction of inorganic metallic salt serves as an inducer for modulating crystalline nucleation and overgrowth, we have synthesized highly monodispersed silver nanoparticles (AgNPs) (diameter: 48.7–411.9 nm) in the shape of polyhedral quasi-spheres via a household microwave oven. The localized surface plasmon resonance (LSPR) absorption spectrum of AgNPs exhibits a good match to the solar spectrum in the UV to near infrared wavelength range. Consequently, AgNPs dispersed in deionized (DI) water have a great potential for efficient solar heat collecting, able to convert both hot steam and its clustering nanobubbles into macro-bubbles (macroscopic bubbles) in a fast and consecutive manner. The maximum values of solar thermal conversion efficiency, rate of steam, and diameter of the clustered macroscopic bubbles obtained in the preliminary experiments under the best conditions are 82.45%, 16.8 g/(AM1.5 · m 2 · min), and 2.4 cm, respectively. Here we show that the designated system has fast dynamics of steam generation, as well as easy and cost-effective scale-up capability, suggesting that the steam generation system using AgNPs might be feasible after further development.