Fig. 3: Photothermal conversion characteristics of the IENGs.

a Light absorption spectra of the IENGs in the wavelength range of 190–2500 nm. b Surface temperature curves of the IENGs under a solar light intensity of 1.0 kW· m−2. c Side surface temperature images of the IENG recorded via IR camera. d IR thermal imaging of the IENG evaporation interface. e Time-dependent side surface temperature variation at different depths for the IENG and the bottom-middle-layer.