Structure And Photoelectrocatalysis Performance Of Graphdiyne For Hydrogen Production

Graphdiyne is a new type of carbon material which is firstly synthesized by Chinese scientist.It is consisted of sp and sp² hybrid carbon atoms.Such flat carbon?sp+sp²?networks exhibit a high degree of?-conjunction,and have unique diacetylene linkage and pore structure.The unique structural features of graphdiyne give it special electronic structure,thus it has been widely used in the research of catalysis field.However,limited by its low crystallinity,the crystal structure of graphdiyne remains to be further characterized.In addition,the further study on the application of the unique electronic structure of graphdiyne is needed.In this dissertation,we synthesized a high crystallinity graphdiyne nanosheets using a modified traditional synthesis method.We investigate the crystal structure of the high crystallinity graphdiyne nanosheets by low-voltage transmission electron microscope?TEM?using low current density.Besides,based on the high hole transmission performance of graphdiyne,through the preparation of two-dimensional graphitic carbon nitride/graphdiyne?g-C₃N₄/GDY?composition,the separation efficiency of photocarriers of g-C₃N₄ has been improved effectively,thus the photoelectrocatalytic water splitting hydrogen evolution performance has been enhanced.The details described as follows:1.We synthesized high crystallinity graphdiyne nanosheets using a modified Glaser-Hay coupling reaction.HRTEM using an electron beam of 120 kV from a LaB₆ gun and a 60 kV beam from a field-emission gun with low current densities was employed to enable the direct high-quality imaging of the crystal structures of the nanosheets.Several characterization techniques,namely,SAED,electron energy-loss spectroscopy?EELS?,and HRTEM simulations were performed.HRTEM imaging indicated that the as-synthesized nanosheet was crystalline graphdiyne with a thickness of 2.19 nm?six layers?and the ABC stacking mode.2.Using the high hole transmission performance,through the hydrothermal reaction,we synthesized g-C₃N₄/GDY compositions as the photocathode.And we research the photoelectrocatalytic water splitting hydrogen evolution performance of the photocathode.The experimental results show that the g-C₃N₄/GDY photocathode exhibits enhanced photocarriers separation due to excellent hole transfer nature of graphdiyne and the structure of heterojunction of g-C₃N₄/GDY,realizing a 7-fold increase in electron life time?610?s?than that of g-C₃N₄?88?s?,and a 3-fold increase in photocurrent density?-98?A/cm²?than that of g-C₃N₄ photocathode?-32?A/cm²?at a potential of 0 V vs NHE in neutral aqueous solution.The photoelectrocatalytic performance can be further improved by fabricating Pt@g-C₃N₄/GDY,which displays an unprecedented photocurrent of-133?A/cm² at a potential of 0 V vs NHE in neutral aqueous solution.