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质子交换膜燃料电池具有零污染、能量密度高、操作温度低和超静低音等优点,因而广泛应用于新能源汽车动力电源.然而质子交换膜燃料电池阴极氧还原反应(ORR)过程缓慢且复杂,因此需要大量的高性能ORR电催化剂.商品铂基催化剂是目前最为广泛使用的ORR催化剂,然而其高昂的价格阻碍了燃料电池汽车的商业化进程.因此,近年来人们致力于研发高性能的非贵金属ORR催化剂,并成功获得了具有高ORR活性及优异稳定性的催化剂.然而开发贵金属替代催化剂还存在制备过程较为复杂、单体有毒等缺点.核黄素具有成本低廉、无毒、氮含量高等优点,本文将其直接作为碳源和氮源,以无水氯化铁为铁前驱体,通过简单的一步热解法制备了高性能的Fe–N–C催化剂.表征结果表明,合成的催化剂表面由于氮的掺杂导致石墨烯存在较多的缺陷,其比表面积为301 m~2g~(–1)且孔径分布主要位于45 nm处;催化剂由很薄、卷曲的石墨烯片层和一些颗粒组成,其中的碳材料高度石墨化且存在Fe_2O_3晶体.结合X射线光电子能谱和催化剂的ORR活性,推导出石墨化氮为ORR的主要活性位,铁在ORR反应中也起着重要作用.在氧气饱和的0.1 mol L~(–1) KOH溶液中,Fe–N–C催化剂的ORR活性达到4.16 mA cm~(–2),与商品Pt/C催化剂相当(4.46 mA cm~(–2)).采用计时电流法在0.66 V(相对于RHE电位)下运行3 h后,Fe–N–C催化剂电流仅下降了3%,而Pt/C催化剂下降了40%,表明Fe–N–C催化剂与Pt/C催化剂具有相近的ORR活性,但稳定性比Pt/C催化剂更出色.测试结果表明,Fe–N–C催化剂的抗甲醇毒化性能远优于Pt/C催化剂.在酸性介质中,Fe–N–C催化剂的ORR活性比Pt/C催化剂低,但稳定性更高.总之,该Fe–N–C催化剂在碱性介质中有较高的活性和稳定性,在酸性介质中有较高的稳定性.因此,我们采用廉价、无毒的核黄素作为碳氮源,通过简单的一步热解法制备出的Fe–N–C催化剂能较好地满足燃料电池ORR催化剂高性能和低成本的要求,具有很好的应用前景.
Proton exchange membrane fuel cells are widely used in new energy vehicles because of their advantages of zero pollution, high energy density, low operating temperature and ultra-quiet bass. However, the process of cathodic oxygen reduction (ORR) in proton exchange membrane fuel cells is slow and complicated , So a large number of high performance ORR electrocatalysts are needed.Product platinum catalysts are the most widely used ORR catalysts at present but their high price has hindered the commercialization of fuel cell vehicles.Therefore, Non-precious metal ORR catalyst, and successfully obtained a catalyst with high ORR activity and excellent stability.However, the development of precious metal alternative catalyst also has the preparation process is more complex, monomer and other shortcomings of toxicity.Ribonin has the advantages of low cost, non-toxic, nitrogen content In this paper, high-performance Fe-N-C catalyst was prepared by simple one-step pyrolysis method using carbon monoxide and nitrogen as the source and anhydrous ferric chloride as iron precursor.The characterization results show that the synthesized Due to the doping of nitrogen on the surface of the catalyst, graphene has many defects, its specific surface area is 301 m ~ 2g -1 and the pore size distribution Mainly located at 45 nm.The catalyst consists of a thin, curly graphene sheet and some particles, of which the carbon material is highly graphitized and Fe 2 O 3 crystals exist.The combination of X-ray photoelectron spectroscopy and the ORR activity of the catalyst leads to the graphitization Nitrogen is the main active site of ORR and iron plays an important role in ORR reaction. The ORR activity of Fe-N-C catalyst reached 4.16 mA cm ~ (-1) in 0.1 mol L ~ (-1) KOH saturated with oxygen -2), comparable to the commercial Pt / C catalyst (4.46 mA cm -2). After chronoamperometry was operated at 0.66 V (vs. RHE potential) for 3 h, the Fe-N-C catalyst current decreased only 3%, while the Pt / C catalyst decreased by 40%, indicating that the Fe-N-C catalyst and the Pt / C catalyst have similar ORR activity, but the stability is better than that of the Pt / C catalyst. The anti-methanol poisoning performance of-C catalyst is much better than that of Pt / C catalyst.In the acidic medium, the ORR activity of Fe-N-C catalyst is lower than that of Pt / C catalyst, but the stability is higher.In summary, C catalyst has high activity and stability in alkaline medium and high stability in acidic medium, therefore, we use cheap, non-toxic Riboflavin as carbon and nitrogen sources, Fe-N-C catalyst prepared by a simple one-step fumed fuel cell can meet ORR catalyst performance and low cost requirements, has good application prospect.