(a) Schematic illustration of the fabrication route to NiCoFe LDHs/NF via
a two-step hydrothermal reaction, (b, c) SEM images of the hierarchical NiCoFe LDH nanoarrays at different magnifications, (d) polarization curves of different hierarchical LDH electrocatalysts (0.5, 1, and 2 indicate the amount of Fe(NO3
O in reactants in mmol), and (e) stability testing of the H-LDH-1 sample under constant potential in a 1 M KOH solution and (inset) SEM image of H-LDH-1 after stability testing [38
]. Copyright 2014, the Royal Society of Chemistry. (f) SEM images of NiCoFe LDHs/CFC; (g) HAADF-STEM image of a typical NiCoFe LDH nanosheet and the corresponding STEM-EDS elemental mapping images of (h) Co, (i) Fe, and (j) Ni; and (k) polarization curves and (l) corresponding Tafel curves of NiCoFe LDHs/CFC, NiFe DHNAs/CFC, CoFe DHNAs/CFC, NiCo DHNAs/CFC, Ni SHNAs/CFC, Co SHNAs/CFC, and Fe SHNAs/CFC, where DHNAs and SHNAs are double- and single-hydroxide nanosheet arrays in a 1 M KOH solution, respectively [72
]. Copyright 2016, American Chemical Society.