Controllable Doping And Electrochemical Properties Study Of Nickel Cobalt Layered Double Hydroxide

The development and application of clean energy demand new requirements for energy storage and conversion devices.LDH serves as a kind of ideal material for electrode material for supercapacitor and catalysts for water splitting.Its laminate possesses many different kinds of transition metal cations that can be considered as active sites in the electrochemical reaction process.However,some shortcomings restrict its practical application,such as the sluggish charge and ion transport and the incomplete exposure of electrochemical sites.Based on this,the doping method is implemented in this thesis to modify the LDH base material.The vanadium doped NiCo-LDH is prepared and applied as electrode material for supercapacitor.The ruthenium doped NiCo-LDH is prepared and used as catalysts for oxygen evolution reaction?OER?.The main contents are as follows:Firstly,the vanadium doped NiCo-LDH is synthesized by the hydrothermal method.VCl₃ is used as the source of vanadium.The relationship between the vanadium content and the electrochemical performance of the materials is studied.The best ratio of dopants?10 at%?is confirmed.With the introduction of vanadium,the nanosheets become smaller and denser,and the pore structure is optimized.The electrochemical performance of vanadium-doped samples is finally elevated.The vanadium-doped sample possesses a high specific capacitance of 2960 F g^-1 at the current density of 1 A g^-1,and it still retains a specific capacitance of 762 F g^-1 at the current density of 50 A g^-1.Also,the assembled supercapacitor device possesses a wide working window of 1.5V.The energy density is 31.95 Wh kg^-1when the power density is 0.75 kW kg^-1,and it possesses an energy density of 18.125 Wh kg^-1 when the power density is 3.125 kW kg^-1.Moreover,the Ru-doped NiCo-LDH is prepared by the hydrothermal method,and RuCl₃ is used as the source of ruthenium.When ruthenium is introduced into the LDH,the morphology of LDH nanosheets changed.The smaller and closer packed nanosheets of ruthenium-doped LDH samples contribute to the exposure of more active sites.The electrochemical kinetics is elevated,which is confirmed by the lower Tafel slope and impedance.Therefore,ruthenium-doped samples display better electrochemical performance than that of the pristine one.It requires a relatively low overpotential of316 mV to drive 10 mA cm^-2 current density with good stability.