The Construction And Study Of Adjustable Highly Efficient Electrocatalysts For Clean Energy Technologies

The energy crisis and environmental issues are among the most notable of the 21 st century,and search for renewable and clean energy technologies is a hot topic due to energy shortages and growing environmental problems.Hydrogen is a kind of clean,high-energy renewable energy source,and electrochemically water splitting technology is a promising hydrogen production technology,which includes two half reactions of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In order to speed up the overall water splitting rate,the use of electrocatalysts is essential,so it is necessary to develop efficient,cheap and environmentally friendly catalysts for water splitting.Because transition metals and their compounds have a series of advantages of abundant earth reserves,low price and high conductivity,they become a class of electrocatalysts with application potential.In this thesis,we have designed and prepared three kinds of catalysts based on transition metal V,Fe,Co and Ni on nickel foam(NF)with high performance for hydrogen evolution and oxygen evolution reaction using the morphology,electron state and conductivity control strategy.The specific tasks are as follows: Ⅰ.The iron-doped vanadium phosphide electrocatalysts is constructed from V and Fe metal-organic framework(MOFs)by phosphating process.The derived phosphide has inherited the advantages of large specific surface area and porous structure by adjusting the structure and composition of precursor MOF,so realizing the purpose of optimizing the catalytic performance.In addition,the transition metal phosphides enhance the electrical conductivity of the material and facilitates the HER and OER reactions.Ⅱ.The V elemental doped iron-nickel layered hydroxides(Fe Ni-LDH)material is prepared by hydrothermal method,then,the hydrangea-like vanadium-doped iron-nickel phosphide with unique open structure was constructed from V-doped Fe Ni-LDH by tailoring the hydrothermal and phospharization condition,the open structure is conducive to mass transfer and gas release.Also,the introduction of V element enhances the electrical conductivity of the material and enriches the active sites of the electrocatalysts,which is beneficial to improve the activity of the catalyst.Ⅲ.The V-doping Co Ni-LDH precursor was prepared first by hydrothermal method.The vanadium-doped cobalt nickel sulfide/phosphide heterostructure electrocatalysts were prepared by simple continuous vulcanization and phosphating methods.Benefiting from the increased number of catalytic active sites closely related to the surface and interface effects between two different componets,the fast mass transfer,the improved electrical conductivity and the tuned electronic structure of the material by introducing V doping,the electrocatalytic performance of materials is optimized.The physicochemical properties of the materials were studied by SEM,TEM,XRD and XPS characterization techniques,and the electrochemical properties of the materials were investigated by electrochemical techniques such as CV,LSV,I-T,EIS,ECSA.The test results show that the the three kinds of eletrocatalysts show excellent performance for water splitting.