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Study On Preparation Of NiCo2S4-based Composites And Their Electrocatalytic Performance

Posted on:2023-12-31Degree:MasterType:Thesis
Country:ChinaCandidate:X ChenFull Text:PDF
GTID:2531307094975469Subject:Materials engineering
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The development and utilization of clean energy have drawn more and more attention.Owing to its high calorific value and environmental benignity,hydrogen has become an ideal alternative energy to fossil fuel.The water electrolysis has been regarded as the most effective method for hydrogen production.However,a huge energy barrier needs to be overcome in the process of water electrolysis.The usage of electrocatalysts is the most effective way to solve this problem.Compared to noble metal-based electrocatalysts,transition metal sulfides with earth-abundant reserve and excellent electrocatalytic performance have become the current research hotspot in the field of water electrolysis.The bimetallic transition metal sulfide NiCo2S4 possesses excellent electrical conductivity and intrinsic electrocatalytic activity.However,the electrocatalytic performance of NiCo2S4 still cannot meet the needs of production and development.Therefore,in this dissertation,in order to further improve the electrocatalytic performance,a series of NiCo2S4-based composites have been synthesized and the hydrogen evolution reaction(HER),oxygen evolution reaction(OER)and overall water splitting performance have been detailedly investigated.The detailed contents are summsrized as follows.(1)The superdispersed NiCo2S4 nanoparticles anchored on reduced graphene oxide(NiCo2S4/rGO)have been prepared by a simple two-step solvothermal method.The HER performance of NiCo2S4/rGO composites have been optimized by adjusting the ratio of graphene.Under acidic condition,the overpotential,electrochemical double-layer capacitance and charge transfer resistance of NiCo2S4/rGO composite are 115 mV,21.9 m F cm-2 and 12Ω,respectively.Meanwhile,under alkaline condition,the overpotential and Tafel slope of NiCo2S4/rGO composite are 241 mV and 110 mV dec-1,respectively.The excellent HER performance of NiCo2S4/rGO composite can be ascribed to the introduction of graphene,which can avoid the aggregation of NiCo2S4 nanoparticles and provide larger specific surface area for HER process.In addition,the conductive graphene can improve the electrical conductivity of NiCo2S4/rGO composite and accelerate the electron transfer at the two-phase interface.(2)NiCo2S4/CoS2/CFP composites have been prepared on carbon fiber paper(CFP)by a simple two-step hydrothermal method.The HER,OER and overall water splitting performance of NiCo2S4/CoS2/CFP composites have been optimized by adjusting the ratio of NiCo2S4 and CoS2.Firstly,as for HER performance,under acidic condition,the overpotential,Tafel slope and charge transfer resistance of NiCo2S4/CoS2/CFP composite are 189 mV,84 mV dec-1 and 7Ω,respectively;under alkaline condition,the overpotential,Tafel slope and charge transfer resistance are244 mV,151 mV dec-1 and 20Ω,respectively.Secondly,as for OER performance,the overpotential,Tafel slope and charge transfer resistance of NiCo2S4/CoS2/CFP composite are 367 mV,120 mV dec-1 and 2.0Ω,respectively.Furthermore,NiCo2S4/CoS2/CFP composite also exhibits excellent overall water splitting performance with a cell voltage of 1.61 V.The excellent electrocatalytic performance of NiCo2S4/CoS2/CFP composite can be ascribed to the synergistic effect of CoS2 and NiCo2S4,and the conductive carbon fiber paper substrate can accelerate the electron transfer in the electrocatalytic process,thereby enhancing the electrocatalytic performance of NiCo2S4/CoS2/CFP composite.
Keywords/Search Tags:NiCo2S4, Composite electrocatalyst, Hydrogen evolution reaction, Oxygen evolution reaction
PDF Full Text Request
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