The Application And Research Of Amorphous Metal/Alloy In Methanol Electrocatalysts

With the continuously increasing demand of energy along with depletion ofconventional fossil fuel reserves and the rapidly escalating environmental problems,direct methanol fuel cells (DMFCs) have been intensively developed as alternativegreen and sustainable power sources. However, their dependence on expensivePt-based catalysts for both the anode and the cathode make them unsuitable forlarge-scale commercialisation. In order to achieve high power density as well as lowproduction cost of DMFCs, the designing or improvement the catalysts structure isone of the effective ways for improving the activity of direct methanol fuel cellcatalyst.The thesis is focused on the application of the amorphous metal/alloy in DMFCcatalyst, which Pt-NiA/C, PtRu-NiA/C and PtCoA/C catalysts were synthesized andcharacterised，respectively. The thesis mainly consists of three parts as follows:Part I: The research of Pt-NiA/C catalyst for methanol performance of oxidationThe crystalline and amorphous Ni/C cores were synthesized by different methods,and then Pt-modified crystalline Ni/C (Pt-NiC/C) and Pt-modified amorphous Ni/C(Pt-NiA/C) catalysts of core-shell structure were prepared, respectively. The structureof catalysts was investigated using XRD and TEM. XPS and EDS studied theircomposition of two kinds of catalysts. The electrochemical active surface area,catalytic performance for methanol oxidation and CO tolerance were studied byelectrochemical tests with CV and CA. Electrochemical tests showed that thePt-NiA/C is more superior activity and stability than Pt-NiC/C for methanol oxidation.Part II: The research of PtRu-NiA/C catalyst for methanol performance ofoxidationPtRu-modified crystalline Ni/C (PtRu-NiC/C) and PtRu-modified amorphousNi/C (PtRu-NiA/C) catalysts of core-shell structure were prepared by using thecrystalline and amorphous Ni/C cores, respectively. The structure of catalysts wasinvestigated by XRD and TEM. The electrochemical active area, catalyticperformance for methanol oxidation and stability were studied by electrochemical tests. TEM showed that PtRu-NiA/C particle size is smaller. The hydrogen absorption-stripping and CO absorption-stripping showed that the electrochemical active surfacearea and CO tolerance of PtRu-NiA/C are more superior. The result of methanoloxidation indicated that PtRu-NiA/C is more excellent than PtRu-NiC/C. The CAfound that the rate of decay is faster for PtRu-NiA/C catalyst, but the current density ishigher after1000s.Part III: The research of PtCoA/C catalyst for methanol performance ofoxidationThe crystalline and amorphous PtCo/C catalysts (PtCoC/C and PtCoA/C) weresynthesized by different methods, and then heat treatment was used for PtCoA/C.XRD showed structure of catalysts, and the activity of methanol oxidation wasstudied by electrochemical methods. The electrochemical tests indicated PtCoA/C hashigher catalytic activity and stability than PtCoC/C and commercial Pt/C with thesame Pt loading. The electrochemical active surface area of PtCoA/C decreased afterheat treatment. However, the activity and stability of methanol oxidation are moreadvantageous, and the activation energy decreases with increasing heat treatmenttemperature at0.55V and0.60V for PtCoA/C.