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Characterization Of Nano-powers Synthesized From TiN Via Impregnation-thermal Decomposition Method

Posted on:2008-10-03Degree:MasterType:Thesis
Country:ChinaCandidate:R X SunFull Text:PDF
GTID:2121360242956232Subject:Marine Chemistry
Abstract/Summary:PDF Full Text Request
Nano IrOx-TiO2 catalyst with a Ir:Ti atomic ratio of 1:6.5 had been synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method. Electrochemical tests and material analyses had been used to investigate their morphological structure, electrocatalytic activity. The electrocatalytic activity and stability of the powder catalyst of IrOx-TiO2 had been compared with traditional noble metal catalyst. Pt /RuO2-TiO2 with Pt supported on nanoparticle RuO2-TiO2 had been studied primarily for PEMFC and water electrolysis with SPE (Solid Polymer Electrolytes) technology. The main conclusions were as follows:In case of IrOx-TiO2 powder catalyst for water electrolysis:(1)The XRD,XPS,TEM results showed that TiN had been converted to TiO2 rutile-type phase at 350℃and Ir presented as multi-value oxides. TiO2 and IrOx formed a binary solid solution in a rutile phase. A great number of Ir particles with an average crystal size of about 7nm were rich in the surface of the solid solution.(2)Polarization curves showed that the electrocatalytic activity of nano IrOx-TiO2 catalyst synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method was better than traditional impregnation method . The activity for oxygen evolution and hydrogen evolution also was superior to that of pure IrO2.(3)The catalyst of IrOx-TiO2 annealed at 500℃have been examined as oxygen evolution electrocatalysts for SPE water electrolysis and high performance has been achieved. The electrolytic voltage was 1.6V at 1Acm-2 and 80℃, with Ir loading of only 1.2 mgcm-2.These results suggest that this new method is an efficient way to synthesize noble metal oxides catalyst with high activity and low cost for water electrolysis. In case of Pt supported RuO2-TiO2 powder catalyst for water electrolysis and fuel cell:(1)The XRD,TEM results showed that RuO2-TiO2 has been synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method, TiO2 and RuO2 formed a binary solid solution in a rutile phase. The size of Pt/RuO2-TiO2 nano-particles was about 20nm30nm, and demonstrated that Pt had been highly dispersed on RuO2-TiO2 substrates.(2)Cathode polarization curves showed that its ohmic polarization was very lower than that of Pt/C, and demonstrated that RuO2-TiO2 had high conductivity.(3)Pt/RuO2-TiO2 powder catalyst applied on PEM fuel cell exhibited high activity as good as Pt/C. Cyclic polarization curves of Pt/RuO2-TiO2 in 0.5 mol/L H2SO4 +0.5 mol/L CH3OH solution indicated such catalyst had low electrochemical activities with CH3OH, and decreased the side reaction.(4)Reverse polarity experiments showed that Pt/RuO2-TiO2 has excellent stability, and that can consequently prolong life time of the fuel cell.This kind of catalyst is so promising that deserved further research.
Keywords/Search Tags:titanium nitride, nano-powers, electrocatalysis, water electrolysis, fuel cell
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