Dan Ping,Xiao Feng,Jun Zhang,Jianming Geng,Xinfa Dong
Graphical Powered by carbon : A NiCo alloy@C/Ni x Co 1- x O/NF hierarchical nanocomposite fabricated from carbonization of the bimetallic NiCo-MOF/NiCoLDH/NF template showed excellent electrocatalytic activity for the oxygen evolution reaction. Specifically, it exhibited a very low overpotential of 300 mV at a current density of 100 mA cm −2 . LDH=layered double hydroxide, NF=Ni foam, MOF=metal−organic framework. Hierarchically structured bimetallic NiCo-MOF/LDH/Ni foam (NiCo-MOF/LDH/NF; MOF=metal−organic framework, LDH=layered double hydroxides) composites were successfully fabricated by means of the in situ growth of NiCo-MOF on the NiCo LDH buffer-layer-modified NF surface. After carbonization, the derived NiCo alloy@C/Ni x Co 1- x O/NF hierarchical nanocomposite showed excellent electrocatalytic activity with respect to the oxygen evolution reaction (OER); specifically, it exhibited a very low overpotential of 300 mV at a current density of 100 mA cm −2 . The outstanding OER activity of the composite may be attributed to the open structure of the nanocomposite, the formation of the highly dispersed CoNi alloy, and the synergistic interaction between CoNi@C and Ni x Co 1- x O. This work introduces a new strategy for constructing advanced hierarchically structured nanocomposites for diverse applications.
Wang Fumin,Liu Mengchao,Zhang Xubin,Lv Guojun,Sun Mingshuai
In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional (3D) hierarchical ZnO@Ni
x
Co 1− x (OH)
y
core/shell nanowire/nanosheet arrays arranged on Ni foam substrate via a two-step protocol including a wet chemical process followed by electro-deposition. We then characterized its composition, structure and surface morphology by X-ray diffraction, energy-dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy, EDS elemental mapping. Our electrochemical measurements show that the ZnO@Ni 0.67 Co 0.33 (OH)
y
electrode material exhibited a noticeably high specific capacity of as much as 255 (mA·h)/g at 1 A/g. Additionally, it demonstrated a superior rate capability, as well as an excellent cycling stability with 81.6% capacity retention over 2000 cycles at 5 A/g. This sample delivered a high energy density of 64 W·h/kg and a power density of 250 W/kg at a current density of 1 A/g. With such remarkable electrochemical properties, we expect the 3D hierarchical hybrid electrode material presented in this work to have promising applications for the next generation of energy storage systems.
Xu Wang,Peng Zhang,Tong Wang,Osamu Yamamoto,Nobuyuki Imanishi,Miao Wang
Mesoporous NiCo 2 O 4 nanoneedle arrays on graphene film grown directly on a three-dimensional Ni foam have been fabricated by a facile hydrothermal method , accompanied by annealing under air atmosphere. The BET specific surface area of NiCo 2 O 4 @graphene film@Ni foam is as high as 47.65 m 2 g −1 . The porous composites served as a binder-free anode material for lithium-ion batteries display an excellent and stable electrochemical performance with high specific capacities of 1232 mAh g −1 at the current density of 500 mA g −1 over 100 cycles and 1493 mAh g −1 at the current density of 1500 mA g −1 after 230 cycles with Coulombic efficiency higher than 97%. Moreover, a fairly high rate capacity of 586 mAh g −1 retained even at a high current density of 8000 mA g −1 . The outstanding electrochemical performance should be attributed to synergetic effect of NiCo 2 O 4 nanoneedle arrays with mesoporous nature and high specific area as well as graphene substrate supporting, which can accommodate the volume variation during the electrochemical reactions and facilitate the ion and electron transmission.
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