Impact of enhanced electric field on light-induced evaporation process of plasmonic nanofluid

Recently, some studies have shown that the vaporization of plasmonic nanofluids (PNFs) is observed to be more intensive than that of pure water during the light-induced heating process, but the mechanism remains controversial. In this work, we conduct several comparative experiments and molecular dynamics (MD) simulations to investigate the evaporation process of PNFs under the illumination of different monochromatic incident lights, especially focusing on the plasma-mediated evaporation mechanism. Based on the experimental results of silver, gold, and graphite nanofluids, it is found that the evaporation process of PNFs can be heavily promoted under the combined effect of the enhanced electric field induced by the localized surface plasmon resonance (LSPR) and the thermal diffusion. Combined with the electromagnetic theory, a modified MD simulation is developed to analyze the effect of the induced electric field on the evaporation process of PNFs. The results indicate that nanoparticles with the LSPR effect are not only 'heat sources' which transfer the thermal energy to the surrounding media, but also can produce the enhanced electric field to directly impact the motion of water molecules. The effect of localized electric field on the evaporation of PNFs cannot be neglected, especially during the initial evaporation period when the particle temperature is relatively low. The results also reveal that the light-induced evaporation process of PNFs is quite different from the conventional thermo-mediated evaporation process in carbon-based nanofluids. Besides, some necessary conditions for exciting the plasma-mediated evaporation are also discussed. This work can offer some new insights for a comprehensive understanding of the evaporation process of PNFs, which is of fundamental interest to many emerging applications. (C) 2022 Elsevier Ltd. All rights reserved.