Studies On The Controlled Synthesis Of Graphdiyne-Based Heterostructures And Their Electrocatalytic Performances

Graphdiyne(GDY),as a new two-dimensional all-carbon material comprising sp and sp2 hybridized carbon atoms,possesses Chinese independent intellectual property rights.It features various unique properties,such as abundant chemical bonds,infinitely distributed pores,natural bandgap structure,highly conjugated π structure,unevenly distributed surface charge and can be controllably grown on any substrates under mild conditions,showing great advancements in aspect of synthesis,surface modification,device assembly and so on.Since the first successful synthesis of GDY by Li group in 2010,it has generated many new phenomena and properties in the fields of catalysis,energy,intelligent devices,optoelectronics and information,life science,etc.,which has rapidly aroused a worldwide research boom and achieved a series of original research results.According to the National Science and Technology Library,more than 500 research teams in over 60 countries and regions have carried out graphdiyne research.In the report "Research Fronts 2020"internationally released by Institutes of Science and Development,Chinese Academy of Science,National Science Library,Chinese Academy of Science and Clarivate,"Graphdiyne Research" was selected as the Top 10 frontier hotspot in the field of Chemistry and Materials Science.GDY with unique structures and properties highly meets the development requirements of catalysis materials.The uneven distribution of the surface charge of GDY endows it with countless active sites and high intrinsic activity.Another advantage that GDY could be grown controllably on the surface of arbitrary substrates at ambient temperature and pressure is very beneficial for the controllable fabrication and modification of interfaces with high performance.In this thesis,based on the unique chemical and electronic properties of GDY,three types of high-performance GDY-based heterostructured catalysts with well-defined interface structures have been rationally designed and synthesized,and applied to efficient nitrogen fixation to ammonia,electrocatalytic hydrogen production from seawater,and electrocatalytic oxygen evolution reaction.At the same time,the structure-property relationship between the active site structure and catalytic performance during the catalytic process has also been well investigated by combining various characterization methods.This thesis includes the following parts:(1)The first chapter introduced the development background of graphdiyne.The structures and properties of graphdiyne were firstly introduced.Then,we summarized the synthesis methods of graphdiyne and its aggregation structure.Finally,we focused on the latest progress of GDY in the field of catalysis.energy storage,life science,intelligent devices and other aspects.(2)A method for the accurately controllable synthesis of graphdiyne/Prussian blue analog heterojunction catalyst was developed.The highly active interface with well-defined interface structure was successfully constructed,achieving high selectivity,high Faraday efficiency and high ammonia yield for electrocatalytic nitrate reduction to ammonia.The incomplete charge transfer behavior between graphdiyne and Prussian blue analog can significantly increase the number of active sites and improve the charge transfer ability,resulting in high activity and selectivity.(3)The nickel/ruthenium layered double hydroxide nanosheet arrays with different Ni/Ru molar ratio were grown on nickel foam.Then,the in-situ controllable coating of GDY was realized on the surface of nickel/ruthenium layered double hydroxide nanosheet arrays based on the property of GDY that could grow controllably on any substrate surface without damage.A catalytic system with electron donor-acceptor structure possessing incomplete charge transfer property was obtained and showed excellent hydrogen production performance.It was found that the change of Ni/Ru molar ratio could efficiently regulate the morphology and electronic structure of the material and the formation of heterogeneous interface could endow the catalytic system with excellent conductivity,a mass of active sites and ultra-high reactivity.In addition,the graphdiyne coating could effectively inhibit the corrosion of the material and improve the stability.(4)Based on the property of graphdiyne that it could grow gently and controllably on any substrate surface,an in-situ controllable synthesis strategy of graphdiyne coated nickel-copper bimetallic hydroxide nanosheet arrays was proposed.The results showed that the structure and morphology of the catalyst could be effectively regulated by adjusting the ratio of nickel and copper.The strong incomplete charge transfer behavior between graphdiyne and metal atoms significantly enhanced the conductivity of the catalyst,increased the number of active sites,and thus improved the intrinsic activity of the catalyst,which led to excellent alkaline electrocatalytic oxygen evolution performance.