Super-Heating and Micro-Bubble Generation around Plasmonic Nanoparticles under cw Illumination

Abstract

Under illumination, metal nanoparticles can turn into ideal nanosources of heat due to enhanced light absorption at the plasmonic resonance wavelength. In this article, we aim at providing a comprehensive description of the generation of microbubbles in a liquid occurring around plasmonic nanoparticles under continuous illumination. We focus on a common situation where the nanoparticles are located on a solid substrate and immersed in water. Experimentally, we evidenced a series of singular phenomena: (i) the bubble lifetime after heating can reach several minutes, (ii) the bubbles are not made of water steam but of air, and (iii) the local temperature required to trigger bubble generation is much larger than 100 degrees C: This last observation evidences that superheated liquid water, up to 220 degrees C, is easy to achieve in plasmonics, under ambient pressure conditions and even over arbitrary large areas. This could lead to new chemical synthesis approaches in solvothermal chemistry

Volumetric solar heating and steam generation via gold nanofluids

“…As far as the steam generation mechanism is concerned, it has been shown analytically that a minimum radiation flux of 3×10 8 W/m 2 is required to produce nanobubbles on heated nanoparticles [46,49,50], which can only be reached by powerful laser beams. In a separated study, Julien et al [51] showed that 1×10 10 W/m 2 was required to generate a nanobubble on a plasmonic gold nanoparticle.…”

Steam generation under one sun enabled by a floating structure with thermal concentration

“…[8][9][10][11][12] Plasmonic nanoparticles with absorption and scattering cross-sections exceeding their geometrical cross-sections have been recently developed and applied for direct solar steam generation [13][14][15][16][17][18][19][20][21][22][23][24] , but they typically require optical concentration of 10-1000x for steam generation. However, optical concentrators are expensive ($200/m 2 ) 25 , often accounting for a major portion of the capital cost of solar thermal systems.…”

Behavior of microbubbles on spatially controlled golden nanoparticles

“…Numerous studies have been conducted over the past 50 years to understand the formation of photothermal bubble generation mainly under pulsed illumination [16] . In fact, the plasmonic bubble generation under CW illumination had received considerable attention until recently [17] . In 2009, Adleman et al [18] were the first scholars who focused a CW laser on a flowing ethanol-water mixture over gold nanoparticles and provided the necessary heat of heterogeneous catalysis.…”

“…Zhao et al [22] proposed a first application of plasmon-induced microbubbles (MBs) that consisted of generating a surface MB on a metal film as an effective lens for surface plasmon waves in a microfluidic environment. In 2014, Baffou et al [17] investigated a temperature threshold for plasmonic bubble formation, explained their unexpectedly long lifetime, and described the MB steady state maintained under CW illumination. Lombard et al [23] addressed the kinetics of formation of the nanobubbles using a hydrodynamic free-energy model.…”

“…The fact that the plasmonic bubble does not collapse as soon as the heating beam switched off vanishes from the nature of the bubble: it is not made of steam, but of air molecules. If the plasmonic bubbles were made of steam, they would disappear as soon as the heating stopped [17] . Furthermore, the shape of a collapsing bubble is not regular due to the existence of nanopillars, so there are peaks in the picture.…”