Preparation And Properties Of Graphyne-based Nano-electrocatalytic Materials

Zinc-air batteries（ZABs）combine the key characteristics of secondary batteries and fuel cells,making them an important development direction for achieving clean energy conversion,storage,and utilization,which is crucial for the innovation of the new energy industry.The oxygen electrode reactions involved in ZABs include oxygen reduction reaction（ORR）and oxygen evolution reaction（OER）,but their multi-step proton-coupled electron transfer results in high overpotentials.Currently,the most commonly used ZABs catalysts are mixtures of precious metals Pt/C with Ir O2 or Ru O₂,but their lack of uniformity,high cost,and poor cycling performance restrict their large-scale production.Therefore,developing non-precious metal-based dual-functional oxygen electrocatalysts has become a research hotspot.Graphdiyne is a new type of sp and sp² hybrid carbon material that forms a two-dimensional planar structure through the conjugation of benzene rings by1,3-diyne bonds.Its unique sp-C can provide specific sites for designing chemical reactions and achieve controllable doping.In addition,the pore structure composed of18 carbon atoms can limit the loading of metal atoms,which not only modifies the outer electron structure of metal atoms and enhances their catalytic activity but also strengthens the stability of catalytic materials.Furthermore,finely tuning the d-orbital energy levels of metal atoms with the electron-withdrawing properties of heteroatom groups can adjust the adsorption/desorption free energy of*OH and enhance catalytic activity.Therefore,this thesis constructs a graphene-based electrochemical interface through doping and in-situ growth strategies,analyzes the microscopic and macroscopic structures of materials,reveals the catalytic mechanism of oxygen electrode reactions,and clarifies the catalytic active sites,providing theoretical basis and technical support for the preparation of non-precious metal-based dual-functional oxygen electrocatalysts.This is of great significance for promoting the large-scale application of ZABs.The main research contents include:（1）Preparation and performance study of copper-nanoparticle-loaded nitrogen-doped graphene dual-functional oxygen electrocatalystRoughening the surface of the copper foil catalyst used in the preparation of graphene,preparing Cu/GDY precursor by catalyst retention strategy,and using melamine as a nitrogen source to dope it,successfully prepared copper-nanoparticle-loaded nitrogen-doped graphene dual-functional catalyst（Cu NPs/NGDY）with synergistic Cu NPs and Cu Cx.This catalyst has a higher initial potential of 1.0 V and a half-wave potential of 0.86 V,which is superior to commercial Pt/C.The overpotential at 10m A cm^-2 is 350 m V,showing excellent ORR and OER catalytic performance.The liquid ZABs assembled by Cu NPs/NGDY have a high power density of 135 m W cm^-2,and the discharge and charge voltages remain stable with little change.The stability is strong（stable operation for 100 hours）.Theoretical calculations show that*OOH,*O,and*OH adsorb on Cu atoms,indicating that Cu-C is the active site,and the tri-coordinate Cu on N-GDY is conducive to the formation of hydroxide ion by the dissociation of*OH and has good catalytic performance.The experimental results and theoretical calculations provide a simple and feasible strategy for the application of graphdiyne-based electrocatalysts in energy conversion and storage fields.（2）Preparation and performance study of sulfur-doped graphene-induced ZIF-67dual-functional oxygen electrocatalystUsing GDY@ZIF-67 as a precursor,Co/Co N/SC composite materials were constructed by a two-step method.The composite material has a large specific surface area(305.64 m²g^-1)and a multi-scale pore structure distribution（average pore size of6.435 nm）,which is conducive to the exposure of active sites and the rapid transfer of ions,promoting the electrochemical reaction.After electrochemical performance testing,the catalyst showed a higher initial potential of 0.95 V and a half-wave potential of 0.83 V,with an overpotential at 10m A cm^-2 of 350 m V,which is superior to Ir O₂.This composite material shows excellent ORR and OER performance.Using Co/Co N/SC as the cathode catalyst,the liquid ZABs exhibit a high open-circuit voltage of 1.43 V,a maximum power density of 184 m W cm-2,and excellent cycle stability,with stable operation for up to 100 hours.