Synthesis And Electrochemical Properties Of Nanohybrid Systems Based On Noble Metal Materials

Fuel cell technology is derived from the primary battery reaction,which converts the chemical energy of fuel molecules into electrical energy for output.The conversion is not limited by the Carnot cycle,and can achieve extremely high conversion efficiency.In particular,people have paid more and more attention to the health hazards caused by smog weather over the years,which makes this feature important.However,the low electrocatalytic efficiency of the conventional commercial Pd/C catalyst makes the oxidation process of the anode slow,and the high dosage of the catalyst causes high cost,which has become key factors.Many new types of electrocatalysts with high performance,long life and low cost have emerged.Among them,precious metal Pd-based materials have received extensive attention from many fields.Pd exhibits stronger activity than Pt in the electrooxidation catalytic reaction of formic acid.However,Pd element is not very resistant to CO during the catalytic process and is easily deactivated.Therefore,the hybrid system is introduced into the Pd-based material,for example,by incorporating non-precious metal elements for the regulation of the morphology and reaction sites,and doping the catalyst material into a suitable carbon material to increase the speed of transmission,and to improve the power of the catalyst,which is very important.This thesis is devoted to the design and preparation of a series of bimetallic alloy nanoparticles and precious metal-carbon nanomaterials.The morphology and structure of the materials are characterized and the electrocatalytic properties are verified.The structure and properties are discussed.The relationship between the research results is shown as follows:(1)In this paper,a simple method for the thermal decomposition of organometallic solvent salts is presented.The coral-like PdCu bimetallic nanoparticles with large specific surface area has been successfully obtained.In the system of electrooxidation of formic acid,Pd62.5Cu37.5 alloy nanoparticles have the best catalytic performance and stability.In addition,PdCu/C nanocomposites were obtained by compounding PdCu alloy nanoparticles with carbon black support,which further optimized the activity and stability in the electrooxidation of formic acid.And the relationship between various structural factors and electrocatalytic properties and the doping effect brought by the introduction of copper into palladium-based nanomaterials were discussed.(2)In this paper,spherical PdAg alloy nanoparticles were successfully prepared by one-step thermal decomposition method.PdAg alloy nanoparticles with different sizes and compositions were obtained by changing the solubility of metal salts in the precursor.The electrocatalytic properties of PdAg/C nanomaterials synthesized by two-step method and in situ grown PdAg alloy nanoparticles on carbon black were further compared.The effect of the combination of noble metal and carrier on the electrooxidation of formic acid was analyzed.(3)In this paper,a graphene film electrode of Pd was obtained by using a one-step organic metal salt solvothermal in situ growth method on a 3D printed graphene carrier.Firstly,it was confirmed that the graphene carrier has a class porous structure which is favorable for the transmission of gas and electrolyte,and the palladium nanoparticles on the graphene are uniformly distributed and the particle diameter is small through a series of characterization methods.The prepared graphene film electrode of Pd was applied to the electrocatalytic oxidation of formic acid,and it was verified that it can be used as a membrane electrode of a direct formic acid fuel cell.