The Research For Surface And Interface Regulation And Electrocatalytic Properties Of Bi₂WO₆ Nanomaterial

The electrocatalyst constructed by Bi2WO6 nanomaterials and their composite materials has attracted more and more attention from researchers because of the excellent hydrogen and oxygen evolution performance triggered by synergistic catalysis.In this thesis,based on Bi2WO6 nanomaterials,three new types of electrocatalytic nanomaterials,NiS/Bi2WO6-x,NixM1-xS/Bi2WO6,and NiSxN1-xBi2WO6,are constructed using surface and interface control strategies,and their hydrogen evolution and oxygen evolution are discussed.The electrochemical behavior of the three types of nanomaterials was explored.This research enriches the research content of Bi2WO6 nanocomposite materials,and can also provide a reference for the research of electrocatalytic hydrogen evolution and oxygen evolution.The full text is divided into five chapters,and the author’s main contributions can be divided into three areas:1.Using a two-step hydrothermal and annealing process,a series of 0D/2D NiS/Bi2WO6-x heterojunction catalysts are prepared,The catalytic mechanism of OER based on surface-modified NiS/Bi2WO6-x nanomaterials was studied.The results of using XRD,TEM,SEM and XPS for material composition,morphology and surface electronic structure research show that the successful synthesis of NiS/Bi2WO6 heterojunction material,exhibits a 0D/2D hierarchical structure,exposing more active sites and the synergistic coupling of the two-phase interface.Electrocatalytic performance studies show that NiS/Bi2WO6-4 heterojunction materials has the best OER catalytic activity,when the current density is 10 mA cm-2,show the lowest overpotential of 527 mV and the smallest Tafel slope of 238 mV dec-1,Maintains good stability in alkaline environment in the 13 h durability test and the OER performance retention rate is as high as 98.2%.Compared with pure Bi2WO6 nanosheets,NiS/Bi2WO6-4 heterojunction catalyst has significantly enhanced stability and OER catalytic activity.2.Using a two-step hydrothermal and annealing process,a series of 0D/2D NixMi1-xS/Bi2WO6 heterojunction catalysts(0≤x≤1,M=Co,Fe,Mn and Cu)are prepared,and the OER catalytic properties of NixM1-xS/Bi2WO6 nanomaterials based on interface regulation were studied.The results of using XRD,TEM,SEM and XPS to study the composition,morphology and surface electronic structure of the material show that the successful synthesis of NixM1-xS/Bi2WO6 heterojunction materials,exhibits a 0D/2D hierarchical structure,exposed a rich polycrystalline and interface structure,and a synergistic coupling of bi-metals in the interface.Electrocatalytic performance studies show that Ni0.5Co0.5 S/Bi2WO6 heterojunction materials has the best OER catalytic activity,When the current density is 10 mA cm-2,the lowest overpotential is 337 mV and the lowest Tafel slope is 103 mV dec-1,It maintains good stability in an alkaline environment,and the OER performance retention rate is as high as 97.6%in the 24 h durability test.Compared with pure Bi2WO6 nanomaterials and NiS/Bi2WO6-4 nanomaterials,Ni0.5Co0.5S/Bi2WO6 heterojunction catalyst has significantly improved OER catalytic activity.3.Using reduction impregnation method,the surface of NiS/Bi2WO6 is doped with different non-metal heteroatoms to prepare a series of NiSxN1-xBi2WO6 heterojunction materials(N=B,C,N,O and P).The catalytic properties of OER and HER of NiSxN1-xBi2WO6 nanomaterials based on surface regulation was discussed.The results of using XRD,TEM,SEM and XPS for material composition,morphology and surface electronic structure research show that the NiSxN1-x/Bi2WO6 heterojunction material was successfully prepared,presents a 0D/2D hierarchical structure,uniform distribution of heteroatoms and the formation of dual non-metallic cooperative coupling.Electrocatalytic performance studies show that P-NiS/Bi2WO6 electrocatalyst has good OER catalytic activity and stability in alkaline environment.When the current density is 10 mA cm-2,the lowest overpotential is 350 mV and the lowest Tafel slope is 186 mV dec-1,and it maintains good stability in an alkaline environment,and the OER performance retention rate is as high as 86.3%in the 24 h durability test.The N-NiS/Bi2WO6 electrocatalyst has better HER catalytic activity and durability under alkaline conditions.The current density at-10 mA cm-2 shows the lowest overpotential of 433 mV and the lowest Tafel slope of 137 mV dec-1,And it maintains good stability in an alkaline environment,and the HER performance retention rate is as high as 94.6%in the 24 h durability test.Compared with pure Bi2WO6 nanomaterials and NiS/Bi2WO6-4 nanomaterials,P-NiS/Bi2WO6 heterojunction catalyst has significantly improved OER catalytic activity,and the N-NiS/Bi2WO6 heterojunction catalyst has significantly enhanced HER catalytic activity.