Research ArticleAPPLIED OPTICS

Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation

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Science Advances  08 Apr 2016:
Vol. 2, no. 4, e1501227
DOI: 10.1126/sciadv.1501227
  • Fig. 1 Schematic, processes, and photographs of plasmonic absorbers.

    (A) Schematic of an ideal plasmonic absorber. (B) Self-assembly of gold nanoparticles on nanoporous templates to form plasmonic absorbers. (C) Digital camera images of a 1-inch-diameter bare nanoporous template sample and a ≲90-nm-thick Au/NPT sample (observed from the template side). CEAS, College of Engineering and Applied Sciences.

  • Fig. 2 Structures of self-assembled plasmonic absorbers.

    (A) 3D schematic of self-assembled plasmonic absorbers. (B) 3D SEM image of a typical Au/NPT sample. (C and E) Top view (C) and cross-sectional (E) SEM images of Au/NPT sample. The geometry parameters of the Au/NPT sample are the average pore size D ~300 nm and effective gold film thickness ~60 nm. (D and F) Top-view (D) and cross-sectional (F) SEM images of the Au/D-NPT sample with the average pore size D ~365 nm and effective gold film thickness ~85 nm. The insets in (C) and (D) are the corresponding Fourier transform diagrams of Au/NPT and Au/D-NPT, respectively.

  • Fig. 3 Broadband absorption properties of the self-assembled plasmonic absorbers.

    (A) Experimental absorption spectra measured by an integrated sphere in the visible and near-infrared regimes. (B) Experimental absorption spectra measured by specular reflectance in the mid-infrared regime. The thin red, thin black, and thick black lines in (A) and (B) represent the bare nanoporous templates Au/NPT and Au/D-NPT samples, respectively. (C and D) Finite-difference time-domain (FDTD) method-calculated absorption spectra of the bare nanoporous template (red solid line) and Au/NPT (black solid line) samples. The other dashed lines in (C) and (D) represent simulated absorption curves of three virtual geometries, that is, the nanoporous template with gold perforated film (orange), the nanoporous template with gold nanoparticles (green), and the perforated gold film with nanoparticles (blue), respectively. (E) Comparisons of absorption performance between our plasmonic absorbers (black solid line for Au/D-NPT and black hollow line for Au/NPT, respectively) and other reported structures (other colored dashed lines). The absorbance curve of a standard carbon nanotube sample on a silicon substrate was shown by the red dashed line as well. The other colored lines are absorption curves subtracted from the related references, respectively. CNT, carbon nanotube.

  • Fig. 4 Plasmonic absorbers for solar steam generation.

    (A) Schematic of the solar steam experiment. (B) Calculated cross-sectional electric field distributions at four arbitrary wavelengths. (C) Experimental setups for solar steam generation with the solar simulator off (upper) and on (lower). (D) Evaporation mass change of water with (solid lines) and without (dashed lines) the plasmonic absorbers (Au/D-NPT) as a function of time under different solar irradiations: 1 kW m−2 (red line) and 4 kW m−2 (blue line). (E) Solar steam efficiency (black, left-hand side axis) and evaporation rate (blue, right-hand side axis) with plasmonic absorbers as a function of illumination intensity on the absorber surface.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/4/e1501227/DC1

    Materials

    Note S1. Template-assisted PVD procedure for self-assembly of Au/NPT.

    Note S2. Systematic demonstrations of optical absorbance on geometry parameters.

    Note S3. Antireflection and impedance matching by the nanoporous templates.

    Note S4. Physical understandings for differences between the simulated and experimental absorbance (Fig. 3).

    Note S5. Understanding the nonlinear behavior of evaporation rate on light intensity.

    Note S6. Radiation loss of the steam generation system.

    Note S7. Advantages of Au/D-NPT absorber for steam generaton: Comparisons with carbon paint or traditional plasmonic absorbers.

    Note S8. Optical modeling for random gold particles.

    Note S9. Angular dependence of the Au/D-NPT absorber.

    Note S10. Electric measurements and potential applications.

    Fig. S1. Schematic diagrams of the Au/NPT absorber.

    Fig. S2. Measured absorption spectra of Au/NPT absorbers with different pore diameter D.

    Fig. S3. Absorbance of the plasmonic absorbers on pore length H and gold film thickness hf.

    Fig. S4. Schematic diagram of Au/NPT and the propagation direction of light.

    Fig. S5. Effective index and impedance of nanoporous template calculated by Bruggeman effective medium formula.

    Fig. S6. Scheme for the difference between the actual and simulated structures.

    Fig. S7. Simulated absorbance of the Au/NPT absorber with different particle length hp.

    Fig. S8. Comparison of the experimental and simulated absorption spectra of the Au/NPT absorber.

    Fig. S9. Measured temperature of steam as a function of illumination intensity.

    Fig. S10. The radiation loss of the plasmonic absorber surface.

    Fig. S11. Advantages of Au/NPT for solar steam generation.

    Fig. S12. Evaporation comparisons between the Au/D-NPT and carbon black–based absorber (carbon nanotube).

    Fig. S13. Simulated absorbance as a function of particle number N.

    Fig. S14. Angular dependence of the plasmonic absorber.

    References (5056)

  • Supplementary Materials

    This PDF file includes:

    • Materials
    • Note S1. Template-assisted PVD procedure for self-assembly of Au/NPT.
    • Note S2. Systematic demonstrations of optical absorbance on geometry parameters.
    • Note S3. Antireflection and impedance matching by the nanoporous templates.
    • Note S4. Physical understandings for differences between the simulated and experimental absorbance (Fig. 3).
    • Note S5. Understanding the nonlinear behavior of evaporation rate on light intensity.
    • Note S6. Radiation loss of the steam generation system.
    • Note S7. Advantages of Au/D-NPT absorber for steam generaton: Comparisons with carbon paint or traditional plasmonic absorbers.
    • Note S8. Optical modeling for random gold particles.
    • Note S9. Angular dependence of the Au/D-NPT absorber.
    • Note S10. Electric measurements and potential applications.
    • Fig. S1. Schematic diagrams of the Au/NPT absorber.
    • Fig. S2. Measured absorption spectra of Au/NPT absorbers with different pore diameter D.
    • Fig. S3. Absorbance of the plasmonic absorbers on pore length H and gold film thickness hf.
    • Fig. S4. Schematic diagram of Au/NPT and the propagation direction of light.
    • Fig. S5. Effective index and impedance of nanoporous template calculated by Bruggeman effective medium formula.
    • Fig. S6. Scheme for the difference between the actual and simulated structures.
    • Fig. S7. Simulated absorbance of the Au/NPT absorber with different particle length hp.
    • Fig. S8. Comparison of the experimental and simulated absorption spectra of the Au/NPT absorber.
    • Fig. S9. Measured temperature of steam as a function of illumination intensity.
    • Fig. S10. The radiation loss of the plasmonic absorber surface.
    • Fig. S11. Advantages of Au/NPT for solar steam generation.
    • Fig. S12. Evaporation comparisons between the Au/D-NPT and carbon black–based absorber (carbon nanotube).
    • Fig. S13. Simulated absorbance as a function of particle number N.
    • Fig. S14. Angular dependence of the plasmonic absorber.
    • References (50–56)

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