The effects of Al substitution and partial dissolution on ultrathin NiFeAl trinary layered double hydroxide nanosheets for oxygen evolution reaction in alkaline solution
© 2017 Recently, Ni–based layered double hydroxide (LDH) materials have attracted growing interest owing to the remarkable performance for oxygen evolution reaction (OER). Here we demonstrate the preparation of ultrathin Ni 3 FeAl x trinary LDH nanosheets with higher activity and stability than NiFe–LDH nanosheets for OER. The enhancement was derived from Al substitution, which increased the concentration of Ni 3+ active sites on the catalyst surface. Besides, low-coordinated Ni and Fe atoms and defects were formed by partial etching/dissolution of Al 3+ in alkaline solution, which further increased the activity towards OER. To improve the conductivity, Ni 3 FeAl x –LDH (x=0, 0.91, 1.27 or 2.73) nanosheets were also in-situ grown on three-dimensional-networked nickel foam. The binder-free Ni 3 FeAl x –LDH/Ni foam electrodes exhibited further improved catalytic performance compared to the electrodes made of powdery Ni 3 FeAl x –LDHs and nafion binder. The best OER performance was presented by Ni 3 FeAl 0.91 –LDH/Ni foam, showing a Tafel slope of 57 mV/dec, a low overpotential (304 mV) at the current density of 20 mA/cm 2 , and a current density of 235 mA/cm 2 at 1.60 V (vs. RHE). Furthermore, the Ni 3 FeAl 0.91 –LDHs/Ni foam electrode showed excellent long-term stability, maintaining a stable overpotential of 320 mV at 20 mA/cm 2 after testing for 18 h.
Liu, H; Wang, Y; Lu, X; Hu, Y; Zhu, G; Chen, R; Ma, L; Zhu, H; Tie, Z; Liu, J; Jin, Z
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