| Direct methanol fuel cells(DMFCs) have been attracted much attention due to easy storage and supply of fuel, low noise pollution, little environment pollution and high security. The widely used Pt-based electro-catalysts for DMFC anodes were hampered the development of commercial DMFCs, electrochemistry polarization of methanol oxidation and Pt easily poisoned by the intermediates of methanol oxidation were the main reason what lead to descend of DMFCs performance. According to the mechanism of methanol electro-oxidation, the methanol oxidation reaction rate and anti-poisoning ability of electro-catalysts could be improve if "-OH" existed in methanol electro-oxidation process. A effective method is provide activity "-OH" in catalysts prepared process. Niobium oxide was a typical solid acid, and was very stability when H2O as reactant or product in chemical reaction. In this paper, we used Nb2O5·nH2O as cocatalyst for Pt/C and PtRu/C, the preparation and properties of Nb2O5·nH2O was study. Further, emphaticaly analyzes the structure and properties of 10%Nb2O5·nH2O-20%Pt/C and 10%Nb2O5·nH2O-20%Pt10%Ru/C, and their performance for methanol oxidatio were study, too.Nb2O5·nH2O was prepared by ammonia precipitation in the aqueous solvent system, and the aqueous and glycol mixed solvent system using niobium oxalate as precursor. The structure, composition and morphology of product were researched by XRD,TG, IR and SEM. The results showed:Nb2O5·nH2O have different composition and morphology which prepared in different reaction systems, and they would translate into crystal when heat treatment at 600~700℃. According to analysis of reaction process, in aqueous solvent system, Nb2O5·nH2O grain was formed by nucleation-coagulation mode. In aqueous and glycol mixed system, Nb2O5·nH2O grain was formed by addition-surface reaction mode. Cyclic voltammetry(CV) tseted show that the Nb2O5·nH2O which heat treatment at 700℃has reaction activity for reduced H2O2 by O2.Under the optimum conditions, we prepared 20%Nb2O5·nH2O/C.TEM results showed:when 20%Nb2O5·nH2O/C heat treatment at 700℃in inert atmosphere, the particle size of Nb2O5·nH2O is about 10nm which on C surface uniformly. CV tseted show that the 20%Nb2O5·nH2O/C which heat treatment has reaction activity for reduced H2O2 by O2.In aqueous and glycol mixed systems,5%Nb2O5·nH2O-20%Pt/C,10%Nb2O5·nH2O-20%Pt/C and 20%Nb2O5·nH2O-20%Pt/C were prepared. Their electrochemical surface area were study by CV method, the results showed:10%Nb2O5·nH2O-20%Pt/C have the biggest electrochemical surface area. Further, the structure and morphology of 10%Nb2O5·nH2O-20%Pt/C were study by XRD and TEM. The results showed:with the higher of heat treatment temperatur, Nb2O5 would translate in crystal from amorphous state, the crystal structure and distribution state on C surface of Pt were not change by Nb2O5. When 10%Nb205-nH20-20%Pt/C was heat treatment at different temperature, the Pt particle size was study. Compared with 20%Pt/C, the Pt size of 10%Nb2O5·nH2O-20% Pt/C was few change. When 10%Nb2O5·nH2O-20%Pt/C was heat treatment at 700℃,it morphology was study by HRTEM, we can see that the lattice phases of Nb2O5 and Pt on C surface, and they were contected. The surface chemical state of 10%Nb205·nH2O-20% Pt/C was study by XPS, the results showed:with the higher of heat treatment temperatur, the percentage content of Pt0 was decreased, the electro structure of Pt was not change by Nb2O5·nH2O. Compared with 20%Pt/C, the percentage content of "-OH" in 10%Nb2O5·nH2O-20%Pt/C was increased significantly. CV test results showed:the catalytic activity of 20%Pt/C and 10%Nb2O5·nH2O-20%Pt/C which no heat treatment were little different. With the higher of heat treatment temperatur, the catalytic activity of 10%Nb2O5-nH2O-20%Pt/C was increased. Compared with 10%Nb2O5-nH2O-20%Pt/C that no heat treatment, the oxidation peak current of 10%Nb2O5-nH2O-20%Pt/C that heat treatment at 700℃was increased to 3.49 times. Compared with 20%Pt/C that heat treatment at 700℃, the oxidation peak current of 10%Nb2O5-nH2O-20%Pt/C that heat treatment at 700℃was increased to 2.59 times.Chronoamperogram test results showed: with the higher of heat treatment temperatur, the performance of"CO" tolerance of 10%Nb2O5-nH2O-20%Pt/C was increased.10%Nb2O5-riH2O-20%Ptl0%Ru/C was prepared in aqueous and glycol mixed systems. The structure and morphology of catalysts were study by XRD and TEM. The results showed:with the higher of heat treatment temperatur, the alloying extent of Pt-Ru in 10%Nb2O5-nH2O-20%Pt10%Ru/C and 20%Pt10%Ru/C were increased. Compared 10%Nb205-nH20-20%Pt10%Ru/C with 20%Pt10%Ru/C when they were heat treatment at same temperature, the the alloying extent of Pt-Ru in 10%Nb2O5·nH2O-20% Ptz0%Ru/C was worse, and the size of activated particles in 10%Nb2O5·nH2O-20% Pt10%Ru/C was smaller. These showed that Nb2O5·nH2O could hinders the aggregation of activated particles and alloying extent of Pt-Ru in heat treatment process. The surface chemical state of 10%Nb2O5·nH2O-20%Pt10%Ru/C and 20%Pt10%Ru/C were study by XPS, the results showed:the binding energr of Pt was less effect by Nb2O5·nH2O. With the higher of heat treatment temperatur, the percentage content of RuOx was increased. CV test showed:20%Pt10%Ru/C has the best preformance when it was heat treatment at 300℃,10%Nb2O5·nH2O-20%Pt10%Ru/C has the best preformance when it was heat treatment at 700℃. Compared their oxidation peak current, the latter was 1.45 times than that of the former. Chronoamperogram test results showed:wten they heat treatment at same temperatur, the performance of "CO" tolerance of 10%Nb2O5·nH2O-20%Pt10% Ru/C was better than that of 20%Pt 10%Ru/C.Anyhow, Nb2O5·nH2O was a good cocatalyst for Nb2O5·nH2O-Pt/C and Nb2O5·nH2O-PtRu/C which were used to methanol oxidation.
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