Study On Synthesis And Performance Of Graphdiyne-Metal Electrocatalysts

Graphdiyne(GDY)is a new type of two-dimensional carbon material with large?conjugated structure,which is composed of two kinds of hybrid carbon atoms,sp(acetylene bond)and sp²(benzene ring).The unique molecular configuration enables it to have special electronic properties,topological structure,abundant reaction sites and excellent electron transport capacity,which lays a foundation for the construction of GDY based electrocatalysts with excellent activity.In this thesis,using the GDY as carriers,GDY-metal catalysts with different structure are prepared by various strategies includingtheabsorption-stability,compositecarbonsupport,oxidation-stripping-reduction and in-situ growth.The internal relationship between the surface/interface structure of the catalysts and their performance are explored and the mechanism of GDY on the catalytic performance of the catalysts are clarified through experiments and theoretical calculations.The main research contents are as follows:1.The self-supported electrode material of 3D GDY nanosheets anchored 0D NiFe-LDH nanodots(NiFe ND/GDY)are successfully prepared through a adsorption-stabilization strategy using GDY nanowall on carbon cloth as the support.The phase composition,structure characteristics and OER electrocatalytic performance of the NiFe ND/GDY are studied.The results show that the NiFe-LDH nanodots with the size of 2.7 nm are adsorbed and stabilized by rich alkyne bonds and uniform nanopores of GDY;The 3D structure of GDY provides a larger anchoring space for metal and increases the contact area between reactants and electrodes;The strong interfacial interaction between GDY and NiFe-LDH promotes the interfacial charge transfer effectively;The NiFe ND/GDY shows excellent OER catalytic performance in alkaline medium.The mass current density of 631 A g^-1is 70 times higher than that of the commercial Ru O₂(9 A g^-1)at the overpotential of 300 m V,and after 100 hours of continuous operation at a current density of 20 m A cm^-2,the activity retention rate reaches 90%.2.Using thin GDY wrapped carbon nanotubes(CNT@GDY)as support,the Pt,Pd,Ru atomic cluster catalysts(M-ACS/CNT@GDY)are grown in situ on the surface of the support using the lower reduction potential of GDY itself.The morphology,structure,properties and electrocatalytic HER performance of the composite support and the prepared catalysts are characterized by experiments and theoretical calculations.The results show that the composite support has large specific surface area,excellent electrical conductivity,rich charge surface and low reduction potential(-0.09 V vs.RHE);The Pt,Pd and Ru ACs show the sizes of 0.65,1.05 and 1.13 nm and show strong interfacial interaction with the support,respectively;The prepared catalysts show excellent HER activity and stability in 0.5 M H₂SO₄solution.The required overpotential(?₁₀)of Pt-ACS/CNT@GDY was only 23 m V,its mass current density at the overpotential of 100 m V was three times to that of commercial Pt/C,moreover,the required overpotential remains constant after 12 hours of continuous operation at the step current density of 10 to100 m A cm^-2.3.The self-supported electrode material of Co P nanosheets with ultrathin oxygen containing GDY coating(Co P@RGDYO)is prepared by oxidation-stripping-reduction strategy.The structure,surface properties and electrocatalytic performance of GDY,GDYO and the prepared catalysts are studied.The results show that the ultrathin GDY wrapping on Co P surface optimizes the(35)G_H*of the catalyst,increases the number of active sites for reactants and promotes the charge transfer;The residual oxygen-containing groups in the plane of the GDY improve the hydrophilicity of the catalyst surface and increase the adsorption energy of H₂O;Besides,the wrapping of GDY layer enhance the acid and alkali resistance and structural stability of the catalyst;The catalyst shows excellent activity and stability in both acidic and alkaline media,with the overpotential(?₁₀)of 86 m V and 97 m V,respectively,and the current density(10 m A cm^-2)retention rate of more than 82%after 100 hours-continuous operation.4.Polyacrylonitrile nanofibers supported by electrolytic copper foil are used as templates to prepare GDY nanotubes embedded with Cu quantum dots(Cu-GDYNT)by in-situ growth strategy.Ru Cu-GDYNT catalyst is prepared by electrodisplacement method using Cu-GDYNT as support.The morphology,structure,electrocatalytic HER performance and catalytic mechanism of Cu-GDYNT and the prepared catalysts are studied by experiments and theoretical calculations.The results show that the GDYNT have good mechanical strength and large specific surface area,the axial length of the nanotube is more than 40mm,the wall thickness is about 7 nm,and the uniform size of the embedded Cu quantum dots is about 2.2 nm;In the Ru Cu-GDYNT catalyst,the size of Ru nanoparticles is 2.0 nm,and the presence of Cu atoms in the plane of the GDY increases the binding energy between Ru and GDY,and optimizes the(35)G_H*.The catalyst exhibited excellent HER performance in the full p H range,with the overpotential(?₁₀)of 17 m V(1.0 M KOH),67 m V(0.5 M H₂SO₄)and 83 m V(1.0 M PBS),respectively.