Multiple Transition Metal Sulfides Preparation And Their Electrocatalytic Properties Study

Because of their special effects,the transition metal sulfide,a kind of nanomaterials have been widely applied in many fields.Such as nickel sulfide(Ni3S2)and molybdenum sulfide(MoS2),have shown good results in both electrolysis water and biosensors.On this base,the nanosheets percursors are grown on the porous foamed nickel through hytdrothermal method.Then different transition metal sulfide products were obtained by treating the precursor secondly.The prepared materials are used as catalyst for hydrogen production and electrochemical analysis.The main contents of this dissertation are as follows:(1)Based on the porous nickel foam(NF),the Ni3S2/NF is generated on the surface of NF through hydrothermal method.Then a film of Ni-Fe-OH@Ni3S2/NF is formed on the surface by soaking Ni3S2/NF in Fe3+ solution for 5 s at 100℃,a layer of dense and thin film of Ni-Fe-OH was formed on its surface.And then Ni-Fe-OH is reacted to FeMoS4 by hydrothermal method with the introduction of ammonium thiothiomolybdate to form a new composite material of FeMoS4@Ni3S2|NF.The electrochemical hydrogen evolution reaction between the generated material FeMoS4@Ni3S2/NF and Ni-Fe-OH@Ni3S2/NF are compared,the FeMoS4@Ni3S2/NF shows better hydrogen evolution performance than Ni-Fe-OH@Ni3S2/NF.Through scanning electron microscope(SEM),it is found that the surface FeMoS4@Ni3S2/NF is thicker and more rough than that of Ni-Fe-OH@Ni3S2/NF,and the specific surface area of FeMoS4@Ni3S2/NF increased,which is beneficial to the exposure of more active sites and can promote the hydrogen evolution reaction.The properties of FeMoS4@Ni3S2/NF is tested by electrochemical detection,which shows that it has the smallest potential of 40 mV at 10 mV cm-2,the lower overpotential is beneficial to the hydrogen production.And the stability investigation shows the material has good stability.(2)Ideal electrocatalyst for hydrogen evolution reaction demands abundant reactive centers with high activity,fast electron and mass transfer,unhindered release of gas bubbles and long-term operation stability.Engineering different components’ interface of the composite catalyst can lead to significantly enhanced performance.In this study,excellent activity of NiMo3S4|Ni3S2 seamlessly grown on 3D conductive framework has been demonstrated.Two-step approach has been adopted to synthesize the final catalyst via subsequently reacting(NH4)2MoS4 with Ni(OH)2 nanosheets array hydrothermally grown on nickel foam.As compared to the MoS2|Ni3S2 obtained by directly reacting(NH4)2MoS4 with the nickel foam,NiMo3S4|Ni3S2 demonstrates much superior behavior in terms of current density and Tafel value.On basis of the data analysis,the variance of electrochemical surface area(ECSA)and electron transfer resistance are not the key descriptor for performance of the electrocatalyst in this study.It is considered that the new formed interface between NiMo3S4|Ni3S2 contributes significantly to the boosted activity.Such nanostructured architecture shows promising results for hydrogen evolution reaction in alkaline medium with only 23.4 mV overpotential for the current density of 10 mA cm-2 and robust long-term stability during more than 20 hours test.(3)By using the materials synthesized in the last chapter,the synthesized NiMo3S4|Ni3S2 composite materials were dissolved in the nafion dispersions and were droped to the glassy carbon electrode to detect the hydrogen peroxide in the alkaline solution.The spherical nanoparticles have a large specific surface area,giving them excellent electrocatalytic activity for hydrogen peroxide.The results show that two kinds of composite materials with transition metal sulfides have good catalytic effect on hydrogen peroxide.