Study On Synthsis Of Nitrogen-doped Porous Carbon Materials By MOF And Their Oxygen Reduction Reaction Performance

Increasing energy demands have stimulated intense research on alternative energy conversion and storage systems with high efficiency,low cost and environmental benignity.Catalysts for oxygen reduction and evolution reactions are at the heart of key renewable-energy technologies including fuel cells and water splitting.However,the cathode ORR is six or more orders of magnitude slower than the anode hydrogen oxidation reaction and thus limits the performance of fuel cells.Developing suitable catalysts for ORR becomes very important.As is well known,the platinum materials have been regarded as the most active catalysts for ORR in fuel cells,but they suffer from high cost,low tolerance to methanol and limited stability.There are several kinds of Pt-free catalysts: Cheaper noble metal catalysts,Non-precious metal catalysts,Metal-free catalysts.The use of Metal-organic frameworks(MOFs)as precursors to prepare highly efficient porous carbon catalysts is a non-precious metal catalysts.Larger surface areas and various pore distributions of MOFs are benefcial for adsorbing organic molecules,and porous carbons doped with different elements and metals can be further obtained.Recently,heteroatom-doped porous carbons have been reported,which show good electrocatalytic activity toward ORRs.The doping is found to alter the electron density of carbon,thereby generating the active sites needed for ORR post-treatment of as-synthesized carbon materials with a nitrogen-containing precursor,postdoping.N-doped carbon materials exhibit unique electronic properties,such as high electrical conductivity and good selectivity toward ORR,which originates from the conjugation between the graphene p system and the nitrogen lone-pair.Therefore,N-doped carbon is an excellent candidate for the ORR.In general,N-doped Carbon material prepared from MOFs has essential properties such as high electronic conductivity,good corrosion resistance,excellent surface properties and low cost.The first chapter introduces the recent research progress of ORR catalysts and classifies the ORR catalysts,and reports on the significance of this topic and the progress of the research.In the second chapter,a kind of nitrogen-containing MOF was synthesized by using 5-carboxybenzotriazole and cobalt ions.The carbon material was sintered by sintering and then doped with carbonaceous material using melamine as nitrogen source.Then the material was pyrolyzed at different temperatures.The effects of catalytic activity and nitrogen content and the structure of the materials were investigated by SEM,TEM and XPS.The relationship between the catalytic activity and the nitrogen content and the structure of the materials was explored to find out the relationship between the catalytic activity and the nitrogen content of the catalyst.Thereby we can find the pyrolysis temperature of the catalyst with the best ORR activity.The third chapter mainly describes the synthesis of a nitrogen-containing MOF which was synthesized using 4-(1H-1,2,4-triazol-1-yl)benzoic acid and nickel nitrate hexahydrate.Three kinds of nitrogen-doped carbon materials were obtained in the same way as in Chapter 2.And we explored the ORR performance of these three materials.Then,the structure of the materials was explored by SEM and TEM.And then find out why the different catalysts have different catalytic activity.In the fourth chapter,we summarize the structure of two kinds of MOFs-based nitrogen-doped carbon materials and the catalytic performance of ORR.