Research ArticleCHEMICAL PHYSICS

A spongy nickel-organic CO2 reduction photocatalyst for nearly 100% selective CO production

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Science Advances  28 Jul 2017:
Vol. 3, no. 7, e1700921
DOI: 10.1126/sciadv.1700921
  • Fig. 1 Structure of the laser-chemical tailored spongy Ni(TPA/TEG) catalyst.

    (A) Scanning TEM (STEM) images and energy-dispersive x-ray spectroscopy (EDX) mapping of the spongy Ni(TPA/TEG) nanostructure. (B) STEM image of the Ni(TPA/TEG) particles. (C) Three-dimensional tomographic reconstruction of a fraction of spongy Ni(TPA/TEG) composite (movie S1). (D) TEM image of the spongy Ni(TPA/TEG) nanostructure. The inset high-resolution TEM image displays the defective (020) lattices [d(020) = 1.02 nm] of an orthorhombic crystal. (E) Scanning electron nanodiffraction series taken from the Ni(TPA/TEG) particle by a scanning nanoprobe with an electron beam size of ~3 nm. The probe step size is 10 nm with an exposure time of 0.5 s at each step and a total beam current of ~5 pA. (F) Diffraction patterns showing the [100] and [111] orientations of the orthorhombic Ni(TPA/TEG) composite (movies S2 and S3). The dimensions of the diffraction patterns are 11.9 nm−1 × 11.9 nm−1.

  • Fig. 2 Comparison of laser-chemical tailored Ni(TPA/TEG) and Ni(TPA) composites.

    (A) Proposed design strategy of the disordered spongy Ni(TPA/TEG) composite by introducing soft Ni-TEG building units into a Ni(TPA) framework through laser-chemical reaction. XRD patterns (B), FTIR spectra (C), EDX spectra (D), TGA curves (E), and XPS spectra (F) of the laser-chemical tailored Ni(TPA/TEG) and Ni(TPA) composites. a.u., arbitrary units.

  • Fig. 3 Conversion of CO2 to CO by photocatalysis.

    (A) CO evolution on five Ni-based catalysts with different combinations of TPA, TEG, and DMF. The composites synthesized by laser-chemical approach are labeled with “L”; the ones synthesized by traditional heating method are marked with “H.” (B) CO production on different amounts of the Ni(TPA/TEG) catalyst. (C) Average yield of CO in the first 2 hours for five recycling tests. (D) MS of 12CO (blue lines) and 13CO (red lines) produced on the spongy Ni(TPA/TEG) catalyst by using 12CO2 and 13CO2 as gas sources, respectively. m/z, mass/charge ratio. (E) Comparison of CO evolution on five laser-synthesized M(TPA/TEG) (M = Ni, Co, Cu) catalysts. (F) Comparison of H2 evolution on the five M(TPA/TEG) catalysts.

  • Fig. 4 Generation of liquid products on metal-decorated Ni(TPA/TEG) composites.

    Low-magnification (A) and high-resolution (B) TEM images of the Ni(TPA/TEG) composite decorated with Ag nanocrytals. (C) EDX mapping of the as-prepared Ni(TPA/TEG)-Ag composite. (D) Comparison of the amount of the products (CO, HOOH, and CH3COOH) generated from photocatalytic CO2 reduction on Ni(TPA/TEG), Ni(TPA/TEG)-Rh, and Ni(TPA/TEG)-Ag catalysts.

  • Fig. 5 Comparison of the liquid products generated from photocatalytic CO2 reduction reactions (CO2RR) and CO reduction reactions (CORR) on two catalysts.

    (A) Ni(TPA/TEG). (B) Ni(TPA/TEG)-Ag.

  • Fig. 6 Proposed mechanisms for the photocatalytic conversion of CO2 to CO and of CO to other liquid products.

    (A) Visible light reduction of the photosensitizer [Ru(bpy)3]2+, which transfers an electron to the Ni(TPA/TEG) catalyst to convert CO2 to CO (B) and to Ni(TPA/TEG)-(Ag/Rh) catalysts for the generation of HCOOH, CH3COOH, and CH3CH2OH from further reduction of CO (C). The STEM image in (C) is the Ag-decorated Ni(TPA/TEG) catalyst (the original STEM image is shown in fig. S15). (D) Possible conversion pathways leading to the formation of HCOOH, CH3COOH, and CH3CH2OH via proton-coupled one-, four-, and eight-electron steps, respectively.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700921/DC1

    Materials characterizations

    Three-dimensional tomographic reconstruction of the spongy Ni(TPA/TEG) network

    Comparison of the samples synthesized by laser-chemical route and traditional heating method

    Control experiments to confirm the origin of the evolved CO

    fig. S1. Structure of the selected rigid TPA linkers and soft TEG linkers for the laser synthesis of the nickel-organic photocatalyst.

    fig. S2. Morphology and composition of the spongy Ni(TPA/TEG) composite.

    fig. S3. Nitrogen physisorption measurements of the spongy Ni(TPA/TEG) catalyst.

    fig. S4. A comparison between the measured and simulated powder XRD patterns of the crystalline Ni(TPA) framework.

    fig. S5. Electron diffraction of the Ni(TPA/TEG) catalyst.

    fig. S6. STEM images show the morphologies of five nickel-organic composites synthesized either by the laser-chemical approach (L) or the conventional heating method (H).

    fig. S7. Comparison of the structure of Ni(TPA/TEG) and Ni(TPA) composites synthesized by both laser-chemical (L) and heating (H) methods.

    fig. S8. Brunauer-Emmett-Teller surface area of five as-synthesized nickel-organic composites, including Ni(TPA/TEG) (L), Ni(TEG) (L), Ni(TPA)-DMF (L), Ni(TPA)-TEG (H), and Ni(TPA)-DMF (H).

    fig. S9. CO production rate on different amounts of the Ni(TPA/TEG) catalyst.

    fig. S10. Powder XRD patterns of the spongy Ni(TPA/TEG) catalyst before and after 24-hour photocatalytic reactions.

    fig. S11. Controlled photocatalysis experiments by applying the Ni(TPA/TEG) (L) catalyst in either CO2 or He gas, and without adding catalyst in CO2.

    fig. S12. Comparison of the morphology and structure of the five laser-synthesized M(TPA/TEG) (M = Ni, Co, Cu) catalysts, including Ni(TPA/TEG), NiCo(TPA/TEG), Co(TPA/TEG), NiCoCu(TPA/TEG), and Cu(TPA/TEG).

    fig. S13. Comparison of the yield of CO and H2 on five laser-synthesized M(TPA/TEG) (M = Ni, Co, Cu) catalysts after a 6-hour photocatalytic CO2 reduction reaction.

    fig. S14. Comparison of the gas products evolved from the laser-synthesized Ni(TPA/TEG) and Ni(TEG) catalysts.

    fig. S15. MS of acetic acid (CH3COOH) produced from the photocatalytic reduction of CO2 using the Ni(TPA/TEG)-Ag catalyst.

    fig. S16. Comparison of the liquid products generated from photocatalytic CO2RR and CORR on the Ni(TPA/TEG)-Rh catalyst.

    fig. S17. STEM image of the Ag-decorated Ni(TPA/TEG) catalyst.

    fig. S18. Comparison of the liquid products generated from photocatalytic CO reduction reactions on the Ni(TPA/TEG)-Ag catalyst at pH 8 and 13.

    fig. S19. Proposed three-cell tandem photocatalytic CO2 reduction system for liquid fuels production.

    table S1. List of other heterogeneous catalysts used for photocatalytic CO2-to-CO conversion.

    movie S1. Three-dimensional reconstructed tomography of a fraction of the spongy Ni(TPA/TEG) composite.

    movie S2. Scanning nanobeam diffraction pattern series showing the [100] orientation of the spongy Ni(TPA/TEG) composite.

    movie S3. Scanning nanobeam diffraction pattern series taken along the [111] orientation of the spongy Ni(TPA/TEG) composite.

    References (5055)

  • Supplementary Materials

    This PDF file includes:

    • Materials characterizations
    • Three-dimensional tomographic reconstruction of the spongy Ni(TPA/TEG) network
    • Comparison of the samples synthesized by laser-chemical route and traditional heating method
    • Control experiments to confirm the origin of the evolved CO
    • fig. S1. Structure of the selected rigid TPA linkers and soft TEG linkers for the laser synthesis of the nickel-organic photocatalyst.
    • fig. S2. Morphology and composition of the spongy Ni(TPA/TEG) composite.
    • fig. S3. Nitrogen physisorption measurements of the spongy Ni(TPA/TEG) catalyst.
    • fig. S4. A comparison between the measured and simulated powder XRD patterns of the crystalline Ni(TPA) framework.
    • fig. S5. Electron diffraction of the Ni(TPA/TEG) catalyst.
    • fig. S6. STEM images show the morphologies of five nickel-organic composites synthesized either by the laser-chemical approach (L) or the conventional heating method (H).
    • fig. S7. Comparison of the structure of Ni(TPA/TEG) and Ni(TPA) composites synthesized by both laser-chemical (L) and heating (H) methods.
    • fig. S8. Brunauer-Emmett-Teller surface area of five as-synthesized nickelorganic composites, including Ni(TPA/TEG) (L), Ni(TEG) (L), Ni(TPA)-DMF (L), Ni(TPA)-TEG (H), and Ni(TPA)-DMF (H).
    • fig. S9. CO production rate on different amounts of the Ni(TPA/TEG) catalyst.
    • fig. S10. Powder XRD patterns of the spongy Ni(TPA/TEG) catalyst before and after 24-hour photocatalytic reactions.
    • fig. S11. Controlled photocatalysis experiments by applying the Ni(TPA/TEG) (L) catalyst in either CO2 or He gas, and without adding catalyst in CO2.
    • fig. S12. Comparison of the morphology and structure of the five lasersynthesized M(TPA/TEG) (M = Ni, Co, Cu) catalysts, including Ni(TPA/TEG),
      NiCo(TPA/TEG), Co(TPA/TEG), NiCoCu(TPA/TEG), and Cu(TPA/TEG).
    • fig. S13. Comparison of the yield of CO and H2 on five laser-synthesized M(TPA/TEG) (M = Ni, Co, Cu) catalysts after a 6-hour photocatalytic CO2 reduction reaction.
    • fig. S14. Comparison of the gas products evolved from the laser-synthesized Ni(TPA/TEG) and Ni(TEG) catalysts.
    • fig. S15. MS of acetic acid (CH3COOH) produced from the photocatalytic reduction of CO2 using the Ni(TPA/TEG)-Ag catalyst.
    • fig. S16. Comparison of the liquid products generated from photocatalytic CO2RR and CORR on the Ni(TPA/TEG)-Rh catalyst.
    • fig. S17. STEM image of the Ag-decorated Ni(TPA/TEG) catalyst.
    • fig. S18. Comparison of the liquid products generated from photocatalytic CO reduction reactions on the Ni(TPA/TEG)-Ag catalyst at pH 8 and 13.
    • fig. S19. Proposed three-cell tandem photocatalytic CO2 reduction system for liquid fuels production.
    • table S1. List of other heterogeneous catalysts used for photocatalytic CO2-to-CO conversion.
    • Legends for movies S1 to S3
    • References (50–55)

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mpg format). Three-dimensional reconstructed tomography of a fraction of the spongy Ni(TPA/TEG) composite.
    • movie S2 (.mov format). Scanning nanobeam diffraction pattern series showing the 100 orientation of the spongy Ni(TPA/TEG) composite.
    • movie S3 (.mov format). Scanning nanobeam diffraction pattern series taken along the 111 orientation of the spongy Ni(TPA/TEG) composite.

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