“…A variety of direct absorption nanoparticles materials had have been analyzed in terms of the enhancement in the photothermal performance, including Ag [27][28][29], Au [30][31][32], CNT (carbon nanotubes) [33][34][35], Cu [36], Al 2 O 3 [37,38], graphite [17], graphene [22], and TiO 2 [39]. In addition to the volumetric heating, direct vapor generation due to localized heating of the As far as the steam generation mechanism is concerned, for nanobubbles to be produced around heated nanoparticles, 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 may only be reached developed by powerful laser beams.…”