Coal-based Nitrogen-doped Carbon Nanotubes Supported Platinum-based Catalyst And Its Electrocatalytic Performance

The consumption of traditional fossil energy has brought huge challenges to our living environment.Direct liquid fuel cells represented by formic acid and methanol have gradually become the darling of the new energy market due to their environmental protection,convenience to carry,and high energy conversion rate.Although Pt electrocatalyst is the most effective anode catalyst for formic acid and methanol fuel cells,it is difficult to develop on the road of commercialization and industrialization due to its low activity,poor stability,poor toxicity resistance and scarcity.To this end,researchers have proposed a variety of solutions,such as compounding Pt with other components and preparing a supported catalyst,which will help enhance its electrocatalytic activity and long-term stability.In this paper,starting with Pt-based catalysts,Pt-based binary and three-way catalysts were prepared through different chemical methods,and loaded on coal-based nitrogen-doped carbon nanotubes and modified graphene.The scanning electron microscope and transmission electron microscope were used X-ray diffraction,Fourier infrared spectroscopy,Raman spectroscopy and other methods to characterize the morphology and structure of the prepared composite material;as an anode catalyst for direct formic acid and methanol fuel cells,test its electrocatalytic performance.（1）Starting from the carbon nanotube preparation process,coal-based polyaniline grown in situ from raw coal is used as a carbon and nitrogen source.The NCNT carrier is prepared by chemical vapor deposition,and Pt and Pd are loaded on the NCNT and CNT,respectively.The XPS test shows that the prepared NCNT contains N element,and the successful doping of N is extremely beneficial to the subsequent preparation of composite materials using NCNT as a catalyst support.Through the particle size statistics in TEM and the calculation of the Scherrer formula in XRD,it is found that the particle size of Pt Pd NPs loaded on NCNT is much smaller than that of Pt Pd NPs on CNT;after electrochemical testing,its electrocatalytic oxidation performance for formic acid has been studied.It is found that the peak current density of the Pt Pd NPs/NCNT catalyst is 549.83 m A mg^-1_metal,which is approximately 2.6times that of the Pt Pd NPs/NCNT(120.83 m A mg^-1_metal).（2）The Te O₃^2-will be reduced by solvothermal method to obtain Te elementary substance.Due to the natural reducibility of Te,it can be used as a self-sacrificial template to reduce Pt Cl₆^2-and Ru³⁺of Pt and Ru elemental substances,and load it on NCNT.SEM images shows that the Te elemental obtained by solvothermal method has a one-dimensional tubular structure.TEM results show that the Pt Ru Te/NCNT catalyst retains its one-dimensional hollow tubular structure.The electrochemical results demonstrate that the peak current density of the Pt Ru Te/NCNT catalyst is 728.3 m A mg_Pt^-1,which is 3.1 times the positive sweep current density(235.9 m A mg_Pt^-1)on the Pt Ru/NCNT catalyst.In addition,the positive sweep peak potential and onset peak potential of methanol electrocatalytic oxidation on the Pt Ru Te/NCNT catalyst are lower than those of the Pt Ru/NCNT catalyst.（3）GO was prepared from natural graphite powder by the improved Hummers method,and then reduced by hydrazine hydrate to obtain GNS.Due to its poor dispersibility and agglomeration,the dispersion in the solvent was improved by modification and the agglomeration was reduced.C-GNS is modified by succinic anhydride by Friedel-Crafts reaction,and then the Pt and Ru precursors were loaded on the GNS before and after the modification by microwave-assisted EG reduction method to prepare two catalysts.TEM results show that the average particle size of Pt Ru NPs on C-GNS and GNS are 4.0±0.5 nm and 10.0±2.0 nm,respectively,which further indicates that C-GNS has better solution dispersibility than GNS;after electrochemical testing,the average particle size is 4.0±0.5 nm and 10.0±2.0 nm.Research on the electrocatalytic oxidation performance of methanol found that the mass activity of the Pt Ru NPs/C-GNS catalyst is 657.3 m A mg_Pt^-1,which is much higher than the 361.1 m A mg^-1_Ptof the Pt Ru NPs/GNS catalyst.It has been tested in a long-term stable operation for 24 hours.The final steady-state current density of the Pt Ru NPs/C-GNS catalyst reaches 58.3 m A mg_Pt^-1,which is about 3.2 times that of the Pt Ru NPs/GNS catalyst(18.2 m A mg_Pt^-1),and has better resistance to CO poisoning.