Preparation And Catalytic Performance Of Fuel Cell Cathode Catalysts On Biomass

Fuel cells are a type of new clean energy device and oxygen reduction reaction?ORR?are their common cathodic electrochemical reaction.The performance of fuel cells is determined by the cathodic ORR because which is slow in kinetics.So development of ORR catalysts is of key importance for fuel cells.Up to now,noble metal platinum based samples are the most effective ORR catalysts with outstanding catalytic performances.Unfortunately,such materials are limited to its high cost and very low reserves.Therefore,it is very desirable to develop efficient and stable non-noble metal ORR catalysts to substitute the precious metal catalysts.Among the reported non-noble metal catalysts,nitrogen-doped carbon materials have attracted more and more attention due to their excellent ORR catalytic activity,high stability and excellent resistance to methanol poison.In this thesis,N-doped carbon materials were prepared as ORR catalysts using biomass as carbon source,and the following studies were carried out.?1?Porous nitrogen-doped carbon spheres were prepared by hydrothermal synthesis followed by pyrolysis using sucrose as carbon source and melamine as nitrogen source.The as-prepared samples were characterized by transmission electron microscopy?TEM?,Raman spectrometry,X-ray diffraction?XRD?,scanning electron microscopy?SEM?and X-ray photoelectron spectroscopy?XPS?analysis.The effect of melamine amount and pyrolysis temperature were investigated.The catalytic activity tests have shown that the as-prepared catalysts were efficient in alkaline medium.Especially,the sample N^0.1CS-900 has shown higher catalytic activity,more anti-methanol toxicity and stability than commercial Pt/C?20%?.In addition,the catalyst follows a 4e-pathway for ORR.?2?FeCo alloy embedded nitrogen-doped biocarbon catalysts denoted as FeCo@NC were synthesized by pyrolysis of the precursors derived from metal nitrate and eggshell membrane.The as-prepared samples have been well characterized by TEM,XRD,SEM,XPS,Raman spectrometry and N₂ adsorption-desorption analysis.The as-prepared samples exhibit high electrocatalytic activity toward ORR under alkaline conditions.Especially,the sample FeCo@NC-800 exhibits superior electrocatalytic activity,stability and resistence for methanol corrosion compared with commercial Pt/C?20%?.The catalyst also exhibits brilliant capacity of supercapacitor.?3?Core-shell type Fe₃O₄@NC-Mn catalyst was prepared by pyrolysis of the precursor fabricated by coating chitosan-Schiff base Mn complex on Fe₃O₄ cores.The ORR activity tests have shown that the Fe₃O₄@NC-Mn exhibited excellent electrocatalytic activity,high stability and anti-methanol toxicity better than commercial Pt/C in alkaline media.In addition,the catalyst follows a 4e-pathway for ORR.