Preparation Of Containing Pt Composite Materials Based On GO And Fe-N/C For Electrocatalytic Oxidation Of Methanol

In order to improve China’s energy structure and ecological environment and achieve the goals of carbon peaking and carbon neutrality,it is necessary to develop a clean and renewable energy conversion device.Direct methanol fuel cell（DMFC）can directly convert the chemical energy of methanol into electrical energy,and has great application prospects in the field of portable electronic equipment power supply due to its high energy conversion efficiency,safety,and economy.As the most efficient anode catalyst for DMFC,single metal Pt has high costs and is prone to poisoning,which limits the commercialization of DMFC.In order to improve the utilization rate of Pt and enhance its anti toxicity ability,researchers have designed more efficient Pt-based catalysts based on the control of Pt morphology,molecular aggregation,multicomponent doping,and support.Based on the above ideas,this thesis aims to improve the electrocatalytic performance of Pt-based catalysts in methanol oxidation reaction（MOR）by loading Pt nanowires and Pt nanoparticles on GO and Fe-N/C carbon based carriers,and doping them with transition metals,The specific content is as follows:（1）Microspheres（Pt NW-GO）composed of Pt nanowires and GO were synthesized by a chemical reduction method without surfactant using a single layer of GO as a carrier and formic acid as a weak reducing agent.Through SEM,TEM,XRD,XPS,ICP-OES,Raman spectroscopy and other characterization methods,the morphology,structure and composition of Pt NW-GO were obtained,and its synthesis mechanism was analyzed.Finally,the activity,toxicity,durability and stability of Pt NW GO’s electrocatalytic methanol oxidation were tested using the CV method and i-t curve.The results show that compared with commercial Pt-C,Pt NW-GO has nearly three times the mass activity of MOR and can perform electrocatalytic oxidation of methanol at lower potentials,while also having excellent toxicity resistance,durability and stability.（2）In order to further improve the activity of Pt NW-GO,by optimizing the reaction steps,reaction temperature and selection of reducing agent,Co-doping Pt NW-GO was carried out to obtain a variety of Pt Co-GO catalysts.The morphology,elemental distribution and electrochemical performance of Pt Co-GO were characterized,and it was found that the mass activity,durability and toxicity resistance of Pt Co-GO synthesized by the two-step method were further improved compared with Pt NW-GO.（3）Fe-ZIF-8 with particle sizes ranging from 50 nm to 500 nm was synthesized by chemical doping using Zn（NO₃）₂·6H₂O and Fe（NO₃）₃·9H₂O as metal precursors and2-methylimidazole as organic ligands.Fe-N/C with a single atom Fe coordination Fe-N₄ site was obtained by high-temperature pyrolysis of Fe-ZIF-8.Fe-N/C of about 100nm was selected as the carrier,and PtNP-Fe-N/C was synthesized,and its morphology,structure and composition were obtained by SEM,TEM,ICP-OES,XRD,XPS,Raman spectroscopy and other characterization methods.Finally,the MOR performance of PtNP-Fe-N/C in acidic media was tested by CV method and i-t curve.Due to the synergistic effect between Pt and Fe and the high efficiency of Fe-N/C support,compared with commercial Pt-C,the electrocatalytic oxidation of methanol activity of PtNP-Fe-N/C increased 2.84 times,the ECSA increased by 3.55 times,and had a lower onset potential and higher CO tolerance and stability,making it a potential anode catalyst for DMFC.（4）On the basis of PtNP-Fe-N/C,a third metal Co was doped,and the effect of the doping of the third metal on the MOR performance of bimetallic catalysts was explored.Fe Co-doped ZIF-8 was prepared by one-step and two-step methods,and the carrier Fe Co-N/C was obtained after pyrolysis,and PtNP-Fe Co-N/C was synthesized by a similar method.The morphology,structure and composition of PtNP-Fe Co-N/C were analyzed using SEM,XRD and ICP-OES.Then,the MOR performance of PtNP-Fe Co-N/C was tested by electrochemical methods,and the results showed that the MOR mass activity of PtNP-Fe₁Co₁-N/C prepared by the two-step method was 2.52 times that of commercial Pt-C.Although the improvement in mass activity is limited,the stability has been further improved compared to PtNP-Fe-N/C.It is expected to further improve the MOR activity of Pt-based catalysts through improved synthesis methods in the future.