Study On Controllable Preparation Of Ni-Co-Se And Its Electrochemical Properties

Recently,with the depletion of fossil energy and the increasingly prominent environmental problems,the development of green and cheap energy materials has attracted more and more attention.Transition metal selenide is considered to be the most promising electrode materials for energy storage and conversion technology due to its low band gap,high electrical conductivity,good stability and rich electronic state.Among the numerous preparation methods for electrode material,electrodeposition is the most simple and rapid method for in-situ synthesis of nano electrode materials.Besides,the morphology of the electrode material is also crucial to the performance.The nanosheet structure has been a hot area of research due to it’s significantly increased surface active area and electroactive sites and increasing energy storage efficiency.Therefore,Ni-Co-Se nanosheet arrays are synthesized by one-step electrodeposition and applied to supercapacitors and direct hydrazine fuel cells.Therefore,the energy density of supercapacitors and catalytic capacity of direct hydrazine fuel cells are improved.The specific research contents of this paper are as follows:(1)Study on the controllable synthesis of NiCoSe2 nanosheet arrays structure and study on the properties of supercapacitorsNiCoSe2 nanosheet arrays were synthesized by one-step electrodeposition method on nickel foam.The electrochemical results show that NiCoSe2 nanosheet arrays has excellent electrochemical properties.The NiCoSe2 nanosheet arrays display a high specific capacity of 520 C g-1 at 1 A g-1,and outstanding cycling stability of 85%during 5000 cycles at 10 A g-1.The NiCoSe//AC supercapacitor,where NiCoSe nanosheet arrays and AC serve as positive and negative electrodes,respectively,displays a high energy density of 44.4 Wh kg-1 at a specific power of 776.7 W kg-1,and realize its practical application value.(2)Study on the controllable construction of Ni0.6Co0.4Se nanosheet arrays structure and its catalytic properties of hydrazine oxidationNi0.6Co0.4Se nanosheet arrays were synthesized by one-step electrodeposition method on nickel foam.The electrochemical results show that Ni0.6Co0.4Se nanosheet arrays has excellent electrochemical properties.Ni0.6Co0.4Se exhibits an enormous current density of 300 mA cm-2 at 0.4 V vs.RHE,and a small onset potential of 25 mV and long durability of 93.6%at 200 mA cm-2 during 20000 s for HzOR.Specially,the mechanistic reason for the enhanced catalytic performance of Ni-Co-Se was discussed.It is found that the nanosheet arrays has superhydrophilic and hydrophobic to enables the gas to escape quickly.(3)Study on electrodeposition mechanism of Ni-Co-Se electrode materialsNanosheet structured NiCoSe2 layer was successfully electrodeposited from a chloride bath by electrodeposition method.The electrochemical mechanisms and its growth and nucleation mechanism of Ni-Co-Se affected by bath temperature were studied.It is observed that both bath temperature and material of the electrode have significant effects on the electrochemical kinetics of Ni-Co-Se electrodeposition.A nucleation loop was not be observed on Pt electrode but a nucleation loop was observed on GC electrode.The cyclic voltammetry curve also plays a guiding role in determining the process parameters.