Preparation And Characterization Of Pt-TiO₂-SiO₂ Mesoporous Materials And Visible-light Photocatalytic Assemble And Performance Of Small Hydrogen-air Fuel Cell

This thesis summarized two parts of the orginal work: part one is preparation andcharacterization of Pt-TiO₂-SiO₂ mesoporous materials and visible-light photocatalyticperformance; part two isdevelopment, crucial materials and applicated of proton exchangemembrane fuel cell (PEMFC). PEMFC stack was assembled and tesed.The main research work is as follows:1. TiO₂-SiO₂ metal oxide materials with a mesostructure have been prepared by a novelmethod in which hydrolysis and condensation of titanium tetraisopropoxide (TTIP) andtetraethoxysilane (TEOS) were controlled by the pH change of acidic solution. The Pt-modifiedTiO₂-SiO₂ catalysts were synthesized by the photo-reduction method. The materials werecharacterized by XPS and nitrogen sorption. The complicated titanium coordiantion states wasinvestigeated by XPS.The BET surface area was only 50m²/g with no Pt loading. The areabecame more and more biger with increasing of the amount of Pt. The result showed thatPt-TiO₂-SiO₂ mesostructured materials with different ration of Si/Ti had different pore diameterand different BET surface area and existed an optimal ration of Si/Ti. the surface area (S_BET) ofthe Ti-Si mixed oxide mesoporous materials increases while the pore size decreases withincreasing Ti incorporation into the silicate framework.In photocatalytic performance, methyl orange (MO) wased photocatalysed with visible-light.The result indicated that the photocatalytic activity of catalyst loading Pt was well than those notloading. The order of activity was 2＞1＞0.5＞0.4 mass ration of Si:Ti. Besides above work, themechanisms of preparation and photocatalytic performance were proposed and discussed.2. The performance of proton exchange membrane fuel cells (PEMFC) were substantiallyinfluenced by the activity of catalyst and composition of catalyst layer in the membraneelectrode assembly (MEA).40ï¼…Pt/C catalysts was synthesized by impregnation-reduction method and characterized byXRD. The results showed that the diameter ofPt/C electrocatalysts was about 2.9nm.More negative factors exised in the former flow field plates and MEA. A new structrue flowfield plate was designed, and a kind of new MEA was provied in the paper. The small hydrogen-air PEMFC stacks were designed and applied in this paper. The performance of the fuel cellstacks was tested.The results of the testing performance showed, the voltage output was 0.92V and the powerdensity was 0.45W/cm² in the single cell. In 7 pieces cell stack, the power output and thepower density was 19.2W and 0.305W/cm² respectively. In 19 pieces cell stack, the power output and the power density was 87.2W and 0.52W/cm² respectively. These cell stacks couldwork stably for a long time, with low noise and high efficiency.