Research ArticleMATERIALS SCIENCE

Exposing unsaturated Cu1-O2 sites in nanoscale Cu-MOF for efficient electrocatalytic hydrogen evolution

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Science Advances  28 Apr 2021:
Vol. 7, no. 18, eabg2580
DOI: 10.1126/sciadv.abg2580
  • Fig. 1 Schematic illustration of the synthetic process for Fe(OH)x@Cu-MOF NB.

    (i) Growth of a conductive Cu-MOF layer over Cu2O nanocube via the reaction of locally dissolved Cu ions with organic ligands during the solvothermal process. (ii) Conversion to Fe(OH)x@Cu-MOF NB through a subsequent redox-etching process, where the exact value of subscript x in Fe(OH)x is undetermined but rather suggests the amorphous nature of the inner Fe(OH)x layer in Fe(OH)x@Cu-MOF NB.

  • Fig. 2 Morphological and structural characterizations.

    (A and B) FESEM images of Cu2O@Cu-MOF nanocubes. (C and D) TEM images of Cu2O@Cu-MOF nanocubes. (E and F) FESEM images of Fe(OH)x@Cu-MOF NBs. (G and H) TEM images of Fe(OH)x@Cu-MOF NBs. (I) HAADF-STEM image and corresponding elemental mapping images of Fe(OH)x@Cu-MOF NBs.

  • Fig. 3 XAFS and XPS characterizations.

    (A and B) The k3χ(k) oscillation curves (A) and the Fourier transform curves (B) of Cu K-edge EXAFS spectra for CuO, Cu2O, Cu-MOF NPs, and Fe(OH)x@Cu-MOF NBs. (C and D) Cu 2p XPS spectrum (C) and Fe 2p XPS spectrum (D) of Fe(OH)x@Cu-MOF NBs. a.u., arbitrary units.

  • Fig. 4 Electrocatalytic performance.

    (A and B) LSV plots (A) and the corresponding Tafel slopes (B) of Pt/C, Fe(OH)x NBs, Cu-MOF NPs, Fe(OH)x + Cu-MOF, and Fe(OH)x@Cu-MOF NBs. (C) Half of the capacitive current density (ΔJ/2) at 0.25 V versus RHE as a function of the scan rate for Cu-MOF NPs, Fe(OH)x + Cu-MOF, and Fe(OH)x@Cu-MOF NBs. (D) I-t curve for Fe(OH)x@Cu-MOF NBs and Pt/C catalysts, where the applied potentials are −0.112 and −0.068 V versus RHE for Fe(OH)x@Cu-MOF NBs and Pt/C catalysts, respectively.

  • Fig. 5 DFT simulation.

    (A) Crystal structure of unsaturated Cu-MOF [Cu3(HHTP)2] viewed along the c axis and the electron density difference plots of corresponding Cu1-O4 and Cu1-O2 centers, where yellow and green contours represent electron accumulation and depression, respectively. (B and C) Calculated partial density of states (PDOS) of Cu-MOF with (B) and without (C) Cu1-O2 centers. (D) Calculated free energy change of adsorbed *H on Cu sites of Cu1-O4 and Cu1-O2 centers.

Supplementary Materials

  • Supplementary Materials

    Exposing unsaturated Cu1-O2 sites in nanoscale Cu-MOF for efficient electrocatalytic hydrogen evolution

    Weiren Cheng, Huabin Zhang, Deyan Luan, Xiong Wen (David) Lou

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