Research On Synthesis Of Nano-porous Carbon With Controllable Doping Structure And Its Catalysis Towards Oxygen Reduction Reaction

The noble metal Pt-based catalysts currently used in fuel cell cathodes have prevented its large-scale commercial applications because of their low abundance and high cost.Therefore,it is important to develop low-cost,highly efficient,stable non-precious metal oxygen reduction reaction(ORR)catalysts to replace Pt-based catalysts.In this paper,two kinds of efficient and stable nano-porous carbon materials ORR catalysts have been developed through reasonable control of doping condition.The main research contents are as follows:Preparation and ORR performance of porous Fe-N co-doped graphite Fe-N-Cx catalysts.The chemical vapor deposition(CVD)was used to pyrolyze carbonyl iron(iron source),ammonia(nitrogen source),and acetylene(carbon source)at different temperatures in an N2 atmosphere to prepare a core-shell precursor(Fe3C@NDC)with iron core and N-doped graphite shell.After pickling and secondary carbonization,Fe-Nx-C catalysts were synthesized with a high-nanometer porous graphite structure.The test results showed that the Fe-Nx-C900 catalyst performed well towards ORR(onset potential: 0.97 V;number of electrons transferred per oxygen molecule(n)was close to 4),and has good stability for possible cross or poisoning effects of ORR,which is close or even comparable to commercial 20% Pt/C catalysts.Preparation and ORR properties of Fe-N co-doped mesoporous carbon Fea-N-MCx based on nitrogen-rich polymer precursor.A nitrogen-rich precursor was synthesized through a polycondensation reaction between methylolmelamines and ferric ammonium oxalate(FAO).The precursor and the hard template Mg O were ground uniformly and carbonized at high temperature in an N2 atmosphere,and then washed by dilute HCl to prepared Fe and N-rich co-doped mesoporous carbon Fea-N-MCx catalysts.Owing to good and uniform mesoporous structure,nitrogen content to 25.9 wt.% and abundant probable active sites of pyridine N and pyrrole N,Fe0.04-N-MC800 had the same onset potential 0.98 V in the alkaline medium as the commercially available 20% Pt/C,the number of electrons transferred per oxygen molecule was close to 4 and had a better long-term durability and methanol tolerance than Pt/C.