Preparation Of Pt And Ru-based Nanocatalysts With Different Size Distribution By Impregnation And Electrochemical Performance Studies

In the process of human beings searching for alternatives to non-renewable energy sources such as fossil fuels,hydrogen energy and fuel cells are attracting much attention because of their green,clean and environmentally friendly features.The catalysts,which play a decisive role in the conversion process,have naturally become the important research direction.The noble metal catalyst represented by Pt is currently a hot research topic because of its excellent catalytic activity,good oxidation resistance,corrosion resistance and electrical conductivity.But so far,the efficient and controllable preparation methods of Pt-based nanocatalytic materials are still lacking.In this thesis,the precious metal base(Pt and Ru)was used as the research object,and the industrially used impregnation method was used as the material preparation method.Combined with physical characterization and electrochemical test methods,the influence of catalyst size control on its electrocatalytic performance was investigated.The main contents of this paper are as follows:First,a PtCu bimetallic alloy nanoparticle having two size distributions was successfully prepared by changing the impregnation solvent,adding a non-noble metal to form a bimetal alloy,and then performing an acid washing step.The microstructure and morphology of the self-synthesized materials were characterized by TEM,HRTEM,EDS and XRD.The results show that the average particle size of the spherical particles of the two distribution sizes under different preparation conditions is 4.7 nm(large particles)and 2.5 nm(small particles),and is uniformly loaded on the Te-doped activated carbon.The half-wave potentials of PtCu/TeC Small NPs and commercial Pt were 0.87 V and 0.85 V,respectively,by electrocatalytic oxygen reduction.The mass activity and specific activity of PtCu/TeC Small NPs were 0.38 A·mgPt-1 and 0.43 A·mgPt-1 were 2.4 times and 3.6 times that of commercial Pt,respectively.In the electrolysis hydrogen evolution reaction,PtCu/TeC Small NPs were tested at full pH,and the overpotential under acidic,basic and neutral conditions was superior to commercial Pt.Secondly,this thesis continues to explore the impregnation preparation of non-Pt noble metal bases,and successfully prepare N-doped supported elemental Ru metal nanoparticles with three size distributions.Under the HRTEM and spherical aberration corrected Transmission Electron Microscope,the spherical nanostructures with average particle diameters of 4.5 nm,2.3 nm and 2 nm were observed.The electrolysis hydrogen evolution reaction was also carried out under the condition of full pH.The acid,alkaline and neutral overpotentials were 106 mV,19 mV and 53 mV at a current density of 10 mA/cm2,respectively,and both exhibited excellent hydrogen evolution levels.In summary,the successful preparation of the above nanocatalyst not only effectively reduces the amount of precious metal Pt in the catalytic process,but also proposes an effective method for industrially preparing uniform and stable nanoparticles.