| The water electrolysis technology is traditional and mature based on the environmental protection requirements in the current hydrogen production. The most important technical problem of water electrolysis is the preparation and research of membrane electrode assemblies (MEA) and catalysts. Platinum catalyst is one of the most widely used MEA’s catalyst. But Pt is rare and the cost of it is very high, so how to reduce the amount of the doped-Pt and improve the properties arc very important.Therefore platinum based catalysts has attracted significant attention recently.In this thesis, new carbon materials(carbon aerogels) have been used as catalys supports and a series of catalysts are prepared. The test and characterization of relevant physical and elcetrocatalysis have been carried out.Pt/carbon aerogel catalysts were prepared by sol-gel polymerization of a mixture of resorcinol and formaldehyde. Water, ethanol and isopropanol were used as solvent. The research of the effect of solvent and the amount of platinum (10wt%,20wt%,30wt%,40wt%)on the performance of the catalysts were investigated. The characteristics of Pt-mounted carbon aerogel sample were obtained by comparing carbon yields, density and volume. Also, the structural behaviour and electrochemical properties of Pt/carbon aerogel were obtained by the Cyclic voltammetry (CV), TEM, SEM, XPS, and X-ray diffraction (XRD) methods. The physical performance of membrane include the moisture content.water loss rate,ion exchange capacity(IEC) and swelling degree.The results indicated that ethanol as solvent had a better performance. And catalysts’s performance increased with the increase of platinum amount in carbon aerogel. However, compared with the Pt/carbon aerogel’s performance with30wt%of the platinum, Pt/carbon aerogel with40wt%of the platinum’s increase was not obvious. Considering the cost factor,30wt%platinum’s CA/Pt in ethanol system has the value for further study. What’s more, the influences of different preparation methods of MEA on the hydrogen production rate of water electrolysis have been studied. The results show that the MEA which obtained by the flow delay molding process using mixed evenly resin catalyst and mixed solution on the base of the pure PEM had better performances.In addition, the Pt-Mo/carbon aerogel catalysts were prepared in ethanol solvent. Pt-Mo/carbon aerogel catalysts showed typical characteristic peaks which demonstrated the Pt-Mo catalyst had a face-centered cubic (fcc) structure. All the particle sizes appeared to be well-dispersed on the surface of carbon aerogel and had a relatively narrow particle size distribution. The results of electrochemical measurements indicated that when the atom ratio of Pt:Mo is3:1, PtMo/carbon aerogel catalyst appeared higher catalytic activity and higher hydrogen production rate in the water electrolysis. The TEM results showed that PtMo particles were well-dispersed on the surface of carbon aerogel with an average size of3nm. XRD characteristic peaks of PtMo/carbon aerogel catalysts were shifted to higher angles with increasing Mo content. XPS results proved the existence of Mo elements,and the state of Mo’s existence is MoO2and MoO3. For the catalysts, the optimum atom ratio of Pt to Mo is Pt3Mo1/carbon aerogel, and its catalytic activity and stability were highest compared with other PtMo/carbon aerogel. And the highest rate of hydrogen production in the water electrolysis was1.65ml/min/cm2。Also, graphene were used as catalys supports, and a series of catalysts with the same amount of platinum (30wt%) were prepared. The membrane electrode assembly was fabricated via the platinum based catalysts.The results indicated that the graphene-supported Pt-Mo catalyst had the highest rate of hydrogen production in the water electrolysis, which reached1.95ml/min/cm2. |
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