Study On The Synthesis Of Defective Catalysts And Their Performances Towards Small Molecule Reduction Reactions

The design of electrocatalysts with high-efficiency,low-cost and durable stability is the key to fulfill their widespread applications.Recently,the regulation of catalytic activity through structure modification has attracted much attention.Among many engineering strategies,defect engineering is of great significance to electrocatalysts.Defects can directly disrupt the periodic crystal structure of materials.Defects affect the surface electronic structure with local electron redistribution.Different defect types,numbers,and locations can render materials many different properties in electrical,optical,and chemical aspects.In this thesis,Fe-doped Bi OCl nanosheets?NSs?with oxygen vacancies?OVs?,Bi₂Se₃ NSs of different thicknesses with adjustable defect concentration,Rh₂Sb nanorods?NRs?with high-index facet,and Bi-Te with a large number of Te defects are synthesized nanoplates?NPs?,and the effects of structure and defects on the catalytic effect have been studied in depth.The main contents are summarized as follows:Chapter 1:The research background of defective catalysts for small molecule reduction reactions is briefly introduced.The basis for selecting the topic,research content and significance of this thesis is clarified.Chapter 2:It was found that the activity of Bi OCl NSs toward photocatalytic nitrogen?N₂?fixation can be significantly enhanced by introducing OVs and Fe doping.Fe doping has a volcanic effect on the photocatalytic N₂ fixation of Bi OCl NSs.Bi OCl NSs-Fe-5%,which has light-switchable surface OVs,optimized electronic structure and strong adsorption capacity for N₂,exhibits the best photocatalytic N₂ fixation performance.Chapter 3:Rh₂Sb NRs with high index facets were successfully prepared for the first time.The high index facets enhance the adsorption and activation of N₂,which makes it exhibit excellent NH₃ yield in the electrocatalytic nitrogen reduction reaction?N₂RR?,which is better than the surface-smooth Rh₂Sb NRs and Rh nanoparticles catalysts.Chapter 4:By controlling the thickness of Bi₂Se₃ NSs,a series of Bi₂Se₃ NSs with different defect contents were synthesized.As the defect content of Bi₂Se₃ NSs increases,the Faraday efficiency and yield of NH₃ in N₂RR increase.Thin Bi₂Se₃ NSs with rich surface defects,fast electron transfer,and efficient absorption and activation of N₂ show excellent N₂RR performance.Chapter 5:After electrochemical activation,significant Te dissolution occurred on the Bi₂Te₃ NPs,resulting in a large number of Te vacancies in the activated Bi₂Te₃ NPs.Theoretical calculations confirm that the Te vacancies will adjust the surface of Bi₂Te₃towards the electrical activity and reduction characteristics through the optimal path of energy to become the active site of small molecules.Experimentally,Bi₂Te₃ NPs with Te vacancies after activation can be used as a multifunctional and stable electrocatalyst for reducing small molecules.It exhibits good catalytic selectivity,activity and stability in electrocatalytic oxygen reduction,carbon dioxide reduction,and N₂RR.