Study On The Transition Metal Compound Catalysts For Cathode Of PEMFC

Proton exchange membrane (PEM) fuel cells have been recognized as the most feasible energy-converting devices for many power-intensive areas, such as portable, stationary, and transportation applications. This recognition is mainly due to their high energy-conversion efficiency and low/zero emissions.In the development process of PEM fuel cells, the high cost of platinum (Pt)-based catalysts is a major barrier to commercialization. Research on reducing Pt loading or completely replacing Pt using non-noble metal catalysts has become increasingly intensive in PEM fuel cell development. In this paper, The nanoparticle of Co3O4 and Co3O4/C catalysts were synthesized by liquid control precipitation method. In order to prepare Fe2N catalyst, the nanoparticle of Fe2O3 precursor was synthesized by homogenous precipitation method, then Fe2N catalyst were obtainded by temperature programmed ammonolysis reaction at different temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize these catalysts in terms of their structure and morphology. To assess catalyst ORR activity, line-scan voltammograms and cyclic voltammograms (CVs) using RDE technique were carried out. The processes of oxygen adsorption on the surface of Co3O4/C were simulated through Materials Studio to explore the catalytic mechanism. The results indicated that:(1) The average size of Co3O4 and Co3O4/C catalysts are 15nm and 10nm, respectively.(2) Co3O4 and Co3O4/C catalysts both had catalytic activity toward the ORR, The electron transfer number for the catalyzed ORR was-3.3, suggesting that the ORR catalyzed by Co3O4/C catalysts is a mixture of 2-and 4-electron transfer pathways.(3) In pauling adsorption mode, theπbond of O2 mainly be weaken by the interaction of Co and adsorbed O. H+ can easily bond with the other O, through 2-electron transfer pathways. In bridge adsorption mode, two O were adsorded and activated at the same time, and the independent of of electron increased. The activity of two O in Bridge adsorption mode is biger than that in pauling adsorption mode, and 4-electron transfer can occur easily.(4) In this paper, the catalytic activity of Fe2N toward the ORR is very low. This may due to the high adsorption energy. On the other hand, the absenceof C support may be the other reason of the low catalytic activity.