Controllable Preparation Of Graphdiyne-based Heterostructure And Research On Catalytic Properties

Graphdiyne（GDY）,as a novel type of two-dimensional carbon allotrope,has independent intellectual property rights in China.Since the first successful chemical synthesis of graphdiyne,it has rapidly attracted widespread attention,and has become a new“hot”research field.As a new type of carbon material with a two-dimensional single atomic layer,composed of sp and sp² hybrid carbon atoms,the unique chemical structure of graphdiyne endows it with unique properties which traditional carbon materials cannot offer,such as abundant carbon chemical bonds,natural large pores,excellent electron/ion transport ability,adjustable band gap,excellent stability and controllable chemical synthesis on any substrate surface.Compared with traditional carbon materials with harsh fabricated conditions,graphdiyne shows great advancements in synthesis preparation,chemical modification,performance regulation,device design,etc.,which very well meets the needs of catalysis,energy conversion,energy storage and other fields.Inspired by the unique chemical and electronic structural properties of graphdiyne,our research mainly focuses on the controlled synthesis of multi-scale graphdiyne based hetero-interfaces,and studies on the performance optimization and the reaction mechanisms during the catalysis,and the electrochemical energy storage properties.A series of graphdiyne-based heterostructures with excellent performances have been successfully fabricated and achieved the fundament and application researches as-prepared graphdiyne-based heterostructures in catalysis,energy storage and other important frontier research fields,resolving the key issues of some traditional electrode materials,including low intrinsic activity,poor electrical conductivity,poor cycle life,etc,and clarified the structure-performance relationship of graphdiyne functional materials in catalysis and energy storage processes.This thesis mainly includes the following parts:It introduces the development of theoretical and experimental research of graphdiyne in recent years.Starting from the special electronic and chemical structure properties of graphdiyne,we summarize the research on its synthesis and aggregation form,and the latest research progress and important achievements in the fields of catalysis,energy conversion and storage.Based on the electron-rich properties and the unique porous structure of graphdiyne,we proposed the basic strategy and method of anchoring Osmium metal atoms on the surface of graphdiyne,realized the controllable growth of Osmium oxide quantum dots with uniform size and controllable morphology on the surface of graphdiyne,successfully obtained the graphdiyne/Osmium oxide quantum dots catalyst（Os O_x QDs/GDY）.The research results show that Graphdiyne realizes the controllable regulation of Osmium valence and coordination environment,efficiently induces of the generation of high coordination osmium(Os⁴⁺)and produces more active sites.Theoretical calculations further prove that the highly coordinated Osmium as the active center has higher catalytic activity for HER.Moreover,graphdiyne can act as a hole transport layer to inhibit the recombination of photo-generated hole-electron pairs,resulting in greatly improving its catalytic performance.Os O_xQDs/GDY exhibited higher catalytic activity under illumination.Compared with the nonillumination condition,the overpotential at a current density of 100 m A cm^-2 is reduced from 210 m V to 42.5 m V in 1.0 M KOH,which indicates that the graphdiyne-based quantum dots catalyst enables efficient photo/electrocatalytic hydrogen production.Based on the strategy of in-situ adsorption-reduction-growth of Bismuth ions(Bi³⁺)on the surface of graphdiyne,the morphological and of Bismuth nanflowers was controlled,and the Bismuth nanoflower/graphdiyne（Bi/GDY）heterostructure catalyst was obtained.The experimental results show this catalyst has abundant active sites,low contact resistance,higher CO₂ adsorption capacity,and shorter diffusion pathways.Bi/GDY exhibits high activity and selectivity for CO₂RR.The maximum Faradaic efficiency is 91.7%at-1.03 V（vs.RHE）,and the formate partial current density is 19.2m A cm^-2;Meanwhile,in a wide voltage window（-1.03--1.43 V vs.RHE）,the highest yield of formate can reach 308.02μmol cm^-2 h^-1,and the maximum cathodic energy efficiency is 58.8%.In addition,the prepared Bi/GDY catalyst was used as a cathode to assemble a Zn-CO₂ prototype battery,and it showed stable charge-discharge performance for more than 30 hours.It further expands the application of graphdiyne-based electrocatalysts in green and efficient utilization of carbon dioxide.Combined with the unique advantage that graphdiyne can grow in situ on any substrate surface,we used Ca CO₃ as a mild template sacrificial layer,and realized the graphdiyne-coated hollow nanostructured silicon oxide（GDY@h-Si O_x）.The experimental results show that the stability of the hollow nanostructures and the electrochemical activity of the electrode materials are improved by in-situ construction of the graphdiyne-based heterojunction interface,which could improve the specific capacity,rate capability and cycle stability.We further develop the application of graphdiyne-based quantum dots catalyst in electrocatalytic nitrogen fixation.Based on the strategy of graphdiyne surface-anchored metal atoms and inducing in-situ nucleation growth,the average particle size of Niobium oxide quantum dots is 3.9 nm,and the graphdiyne/Niobium oxide quantum dots（Nb O_x QDs/GDY）catalyst was successfully obtained.The experimental results show that the catalyst has 13.5%Faraday efficiency and 24.2μg h^-1 mg^-1_cat.yield for electrocatalytic NOR.As for NRR,the Faraday efficiency can reach 41.6%and the yield of NH₃ is 62.1μg h^-1 mg^-1_cat..Graphdiyne could regulate the electronic structure and coordination environment of metal oxide quantum dots,promote charge transfer.Moreover,uniformly distributed quantum dots with high specific surface are beneficial to increase the number of active sites.It realizes bifunctional electrochemical nitrogen fixation.The summary of this thesis.