Research ArticleMATERIALS SCIENCE

Regulating the absorption spectrum of polydopamine

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Science Advances  04 Sep 2020:
Vol. 6, no. 36, eabb4696
DOI: 10.1126/sciadv.abb4696
  • Fig. 1 Synthesis and characterization of TEMPO-doped PDA.

    (A) Schematic illustration of the TEMPO-doped PDA with narrower bandgap and improved light absorption ability compared to conventional PDA. (B) Polymerization of dopamine and TEMPO, together with their molecular structures and powder photographs. (C) SEM image of PDA-3. (D) EELS mapping analysis of PDA-3 (Scale bars, 100 nm). (E) XPS survey spectra of PDA-i (i = 0 to 3). a.u., arbitrary units. (F) C 1s peaks, (G) N 1s peaks, and (H) O 1s peaks in XPS spectra of PDA-3.

  • Fig. 2 Enhanced light absorption and photothermal behavior of TEMPO-doped PDA.

    (A) Photographs of PDA aqueous solutions with concentration of 50 and 100 μg ml−1. Photo credit: Yuan Zou, Sichuan University. (B) L* values of different PDA aqueous solutions. (C) UV-vis-NIR spectra of PDA-i (i = 0 to 3) ranging from 300 to 1500 nm. (D) Temperature elevations of PDA-3 at different concentrations under 808-nm laser irradiation. (E) The photothermal response of PDA-i (i = 0 to 3) aqueous solutions (100 μg ml−1) for 600 s with 808-nm laser irradiation, and then the laser was shut off. (F) Temperature curves of PDA-3 (100 μg ml−1) under four on/off cycles and under 808-nm laser irradiation. The light intensity of 808-nm laser was 2.0 W cm−2. (G) Molar extinction coefficient, ΔT, and total photothermal efficiency of PDA-i (i = 0 to 3). Photo credit: Yuan Zou, Sichuan University.

  • Fig. 3 Electrochemical and DFT measurement of PDA-i (i = 0 to 3).

    (A) CVs of PDA-i (i = 0 to 3). (B) Schematic illustration of the energy levels of TEMPO and PDA-i (i = 0 to 3). (C) Chemical structures of possible moieties within PDA microstructure and theoretical calculated frontier molecular orbital using DFT calculations at the B3LYP/6-31 G(d, p) level.

  • Fig. 4 The light energy conversion process within PDA.

    (A) EPR spectra of PDA-i (i = 0 to 3) with the same mass in the solid states. (B) Transient absorption kinetics traces for PDA-i (i = 0 to 3). (C) Transient absorption spectra of PDA-3 at indicated delay times. (D) The EIA kinetic trace of PDA-3. mOD, mean optical density.

  • Fig. 5 Water desalination experiment.

    (A) A schematic diagram of the solar steam evaporation device based on PDA-3. (B) Photograph of the CM and PDA-3–coated CM. (C) SEM cross-section image of the double-layered film structure. (D) UV-vis-NIR diffuse reflection spectra of the CM and PDA-3–coated CM in the wavelength range of 250 to 2500 nm. (E) IR image of PDA-3–based device under one sun for 15 min. (F) Time course of water evaporation performances of saline water, CM, and PDA-3–coated CM under one sun irradiation. (G) Solar steam efficiency and evaporation rate of saline water, CM, and PDA-3–coated CM. (H) Photograph of the water steam generated under solar illumination of four suns with the PDA-3–coated CM. (I) The ion concentration of the saline water and seawater obtained from Bohai Bay before and after desalination. The dashed lines refer to the standard for drinkable water from the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA), respectively. (J) Evaporation cycle performance of solar desalination devices over 30 cycles, with each cycle sustained more than 1 hour. The inset showed the photograph of absorber after 30 cycles. (K) Evaporation rate among different PDA-based evaporators under one-sun illumination. PVDF, polyvinylidene difluoride. Photos credit: Yuan Zou, Sichuan University.

Supplementary Materials

  • Supplementary Materials

    Regulating the absorption spectrum of polydopamine

    Yuan Zou, Xiaofeng Chen, Peng Yang, Guijie Liang, Ye Yang, Zhipeng Gu, Yiwen Li

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