Preparation Of Doped Graphenes And Their Application In Cathodic Catalyst For Direct Methanol Fuel Cells

Direct methanol fuel cells （DMFC）, a kind of proton exchange fuel cells （PEFC）, areattracting more and more attention for their high efficiency and low pollution. However, thehigh cost and scarcity of Pt intrinsically limit the commercialization of Pt-loaded fuel cells.The essential solution to addressing this shortfall is the development of non-noble metalcatalyst. In this study, we are dedicated to the preparation doped graphenes and theirapplication in cathodic catalyst for direct methanol fuel cells. The dissertation is mainlyfocused on:1. A modified Hummers method is used to prepare graphene oxide. Then the grapheneoxide is reduced by NaBH4or NH3/N2H4to form B-doped graphene or N-doped graphene,respectively. The two materials are characterized by Fourier transform infrared spectroscopy（FTIR） and evaluated by cyclic voltammetry （CV）. It shows that the N-doped grapheneexhibits more excellent stability for oxygen reduction reaction （ORR）.2. A Fe/N/C catalyst is prepared by using graphene oxide as carbon support, andK₃Fe（CN）₆as both nitrogen and iron sources. The non-noble-metal catalyst is furthercharacterized by FTIR and X-ray photoelectron spectroscopy （XPS）. The electrocatalyticactivity of catalyst is evaluated by CV and rotating disk electrode （RDE） experiments. TheFe/N/C catalyst shows high electrocatalytic activity toward ORR in an alkaline solution withan onset potential of-0.15V vs. Ag/AgCl reference electrode. CVs of consecutive sweep for2000cycles are conducted to study the stability of the catalyst. The Fe/N/C catalyst exhibitsexcellent stability and methanol-tolerant ability.3. A facile method for the synthesis of Co/N/C catalyst is developed by using grapheneoxide as carbon support, g-C₃N₄as nitrogen cobalt sources and Co（NO₃）₂as cobalt sources.The non-noble-metal catalyst is further characterized by FTIR. The electrocatalytic activity ofcatalyst is evaluated by CV and RDE experiments. The Co/N/C catalyst shows highelectrocatalytic activity toward ORR in an alkaline solution with an onset potential of-0.06Vvs. Ag/AgCl reference electrode. CVs of consecutive sweep for2000cycles are conducted tostudy the stability of the catalyst. The Co/N/C catalyst exhibits excellent stability andmethanol-tolerant ability.