Accurate Modification Of Sp-C In Graphdiyne

Graphdiyne（GDY）is a new type of carbon allotrope with a highly conjugated skeleton structure and rich acetylenic bond structure.It has huge application potential in the field of catalysis.In 2018,Wang et al.introduced a new form of nitrogen（sp-N）atom into a certain position in GDY through the pericyclic reaction.In alkaline environment,the oxygen reduction electrocatalytic performance of sp-N doped GDY is close to that of commercial Pt/C,which is of great research value.However,in this work,the intermediate products and the reaction process of this experiment have always been“blind box”.If high-quality intermediates can be obtained by designing chemical reactions,it will provide theoretical and experimental basis for understanding the reaction mechanism and obtaining high-purity sp-N doped GDY.Based on this,through the understanding of Click reaction,the GDY was precisely modified at the acetylenic bond site by using p-azidobenzoic acid reaction with the sp-C in GDY.The catalytic performance of hydrogen evolution reaction（HER）and oxygen reduction reaction（ORR）was studied by loading and doping.Through the first Click experiment,it was found that the Click reaction can occur between GDY and p-azidobenzoic acid.Atomic force microscope（AFM）analysis showed that the thickness of the product after Click reaction was increased by 1.1nm on average,which indicated that a Click reaction occurred.Transmission electron microscope（TEM）surface scanning analysis showed that the sample after Click contains N element,and the distribution is uniform,which means the successful grafting of N-containing functional groups.Fourier transform infrared spectroscopy（FTIR）analysis showed that the Click products contained new C-N bond,which preliminarily verified the existence of triazole ring.The existence of triazole ring in the product was further proved by the combination of synchrotron radiation spectrum and X-ray photoelectron spectroscopy（XPS）.Then,it is verified that Click reaction can occur on terminal alkyne and internal alkyne at the same time by designing fluorescence labeled carboxyl functional group and simulating terminal alkyne and internal alkyne,the optimum reaction conditions of Click reaction were determined by experiments as follows:Cu I catalyzed at 80℃for 36 h;Finally,the Click products was loaded with Pt nanoparticles,and the distribution of loaded Pt nanoparticles was found to be uniform by TEM analysis.The electrocatalytic hydrogen evolution performance of Click products loaded with Pt nanoparticles was preliminarily tested.In alkaline environment,the electrocatalytic hydrogen evolution performance of Click products loaded with Pt nanoparticles was significantly improved compared with that of GDY and Click products without Pt nanoparticles.Through the second-step high-temperature pericyclic reaction experiment,it is found that the Click products can be calcined at high temperature to form sp-N doped GDY.The pericyclic reaction process was studied by thermogravimetric-mass spectrometry-infrared coupling,and it was found that the C-N=N⁺fragment on the five-membered ring was removed from the Click products at 550-800℃,and the pericyclic reaction occurred.Synchrotron radiation and XPS have verified the existence of sp-N,which accounts for approximately 11.4%of all nitrogen-doped forms.The electrocatalytic ORR performance shows that in alkaline electrolyte,the limiting current density of sp-N doped GDY(about 4.85 m A cm^-2)is much higher than that of GDY(about 0.95 m A cm^-2).The catalytic performance of the sp-N doped GDY has been improved significantly.