Synthesis,Modification And Properties Towards Oxygen Reduction Reaction Of Carbon Materials

Because of the consumption of fossil fuel and improvement of people's awareness of environmental protection,researchers are devoted to develop efficient,clean and green energy technology.Proton exchange membrane fuel cell(PEMFC)is a kind of device which converts the chemical energy to electric energy directly.It has drawn world-wide attentions because of the merits,such as high conversion efficiency and low environment pollution.While the sluggish reaction kinetic of cathodic reaction restricts the promotion and application of PEMFC.So,it is very essential to develop efficient oxygen reduction reaction(ORR)catalysts.Up to now,although platinum and platinum-based alloys are the preference for PEMFC.The exorbitant price,scarce reserves and weak tolerance are the main challenges.Recently,the carbon based catalysts have obtained great developments because of the facile preparation and better catalytic performance.The main contents and results are summarized as follows:(1)The synthesis,modification of graphene-like materials and their application in oxygen reduction reactionThe graphene-like carbon materials and different heteroatoms(B,S,P)doped graphene-like carbon material are successfully prepared by pyrolysis.Different samples are characterized by X-ray diffraction,X-ray photoelectron spectroscopy and elemental mapping.Meanwhile,electrochemical tests in alkaline environments indicate all the samples exhibit ORR activities.While the sulphur doped carbon nitride exhibits the best catalysic properties.And the ORR is a 4e" pathway with excellent methanol tolerance.(2)The synthesis,modification of mesoporous carbon materials and their application in oxygen reduction reactionMesoporous carbon activated at different temperature(700?,800?,900?)are successfully prepared through template methods.Also,phosphorus doped,nitrogen doped and nitrogen,phosphorus co-doped mesoporous materials are synthesized.The Roman results show the carbon activated at 800?(C-800)exhibits highest ID/IG.Energy Dispersive X-ray detector,X-ray photoelectron spectroscopy,BET tests and scanning electron microscope are used to characterize the physical properties of the samples.Furthermore,the results of electrochemical measurements suggest the NPC-800 has more positive Ep(0.87 V),EORR(0.92 V)and E1/2(0.81 V).And the ORR process on NPC-800 is 4e-pathway.At the same time,it also exhibits better methanol tolerance.(3)The synthesis,modification of biomass derived carbon and their application in oxygen reduction reactionThe cypress leaves(CL),vegetable sponge(VS)and pine needle(PN)are collected as the precursors to synthesize different kind of biomass-derived carbon materials.Through the physical and electrochemical measurements,the VS is selected as the matrix to composite different amount of Co.When 4%Co are composited on the matrix,the VS-Co-4%exhibits the best properties.The VS-Co-4%obtains more positive Fp(0.75 V),EORR(0.87 V),E1/2(0.71 V).Meanwhile,the ORR process is four electron pathway and the VS-Co-4%has better methanol tolerance.(4)The synthesis,modification of carbon sphere and their application in oxygen reduction reactionThe melamine formaldehyde resin are successfully synthesized and calcined at different temperature(800?,900?,1000?)to prepare carbon sphere(CS-X).The Raman test shows the CS-900 has higher ID/IG.Furthermore,the CS are modified with different transition metals(M= Fe,Co,Ni).The results of physical characterization show the transition metal are zero-valent.At the same time,the electrochemical tests show the CS-Co-900 obtains better ORR performance and methanol tolerance.