Preparation And Electrochemical Properties Of Nickel-Based Nanoarrays/Carbon Composites

The use of new energy requires efficient electrochemical energy storage and conversion equipment.Aiming at this goal,two kinds of one-dimensional carbon materials composited with two-dimensional nickel-based oxides and phosphide nanoarrays,are designed and applied to supercapacitors and electrochemical oxygen evolution catalysts,respectively.This design utilizes the high conductivity and good chemical stability of one-dimensional carbon materials,and combines the high electrochemical activity of two-dimensional nickel-based oxide and phosphide nanosheets to form high specific surface area hierarchical porous electrode materials,which improves the electrochemical performance and cycle stability.The main contents of this paper are showed as follows:（1）Core-shell carbon nanofibers@NiMoO₄ composite electrode materials are prepared as cathodes in supercapacitors.NiMoO₄ nanosheet arrays are controllably grown on porous functionalized carbon nanofibers by microwave hydrothermal method.By optimizing the morphology and structure of the electrode materials and improving the pore structure,the high capacity and high rate performance of the electrode are realized.The specific capacity is 1840 Fg^-1 at a current density of 1 Ag^-1,and the capacity retention rate is 78%at a current density of 20 Ag^-1.The asymmetric supercapacitor assembled with activated carbon can work at 1.5 V voltage and provide a high energy density of 23.9 Wh kg^-1at a power density of 0.75 kW kg^-1.（2）The core-shell carbon fiber@Ni_xFe_1-x-P composite electrode materials are prepared as catalysts for electrochemical oxygen evolution reaction（OER）.Ni_xFe_1-x-P catalysts are prepared by using commercial carbon cloth（CC）as structure support framework and collector and Ni_xFe_1-xbased bimetallic hydroxide（LDH）nanoarrays acted as precursors.Through simple heat treatment phosphating of precursors,Ni_0.8Fe_0.2-P/CC samples with good catalytic activity for OER are obtained by adjusting the composition of electrode materials and optimizing the synergistic catalytic effect between Ni and Fe.As a result,a low overpotential of 210 mV at a current density of 10 m^-2 and small Tafel slopes of 41.2 mV dec^-1 are achieved.Moreover,a water electrolyzer is constructed with Ni_0.2Fe_?（0.8）-P/CC used as the anode and Ni₅P₄/CC as the cathode,which achieves remarkable catalytic activity.For getting the current density of 10 mA cm^-2,the overpotential is only 300 mV.