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用共沉淀法制备Fe3O4磁流体,总结出用十二烷基磺酸钠与聚乙二醇作为表面活性剂制备水基磁流体的合适条件:(1)反应温度为室温或不高于35℃;(2)表面活性剂十二烷基磺酸钠的最佳用量为0.0030~0.0040 g/80 mL;(3)第一次包裹的最佳pH为9~10;(4)聚乙二醇作为第二次包裹的表面活剂时,体系最佳温度为40℃左右;(5)表面活性剂聚乙二醇的最佳用量为0.0050~0.0060 g/80 mL。通过实验制得了能稳定存在180 d的水基磁流体。并用透射电镜、红外光谱、分光光度计、古埃磁天平等进行了初步表征。 相似文献
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A composite catalyst Nafion-Pt-HxMoO3 was prepared on a glassy carbon by cyclic voltammetry methods in sulfuric acid solution containing Na2MoO4, H2PtCl6 and Naton, and its activity for the methanol oxidation was studied with Pt-HxMoO3 as comparison. It is found that the electrocatalytic activity and the stability of Pt-HxMoO3 are improved by the Nation. The activity of Pt-HxMoO3 reaches its maximum when the content of Nation in the preparation solution is 0.012%(mass fraction). In this case the oxidation peak current of methanol on Nation-Pt-HxMoO3 is 1.76 times larger than that on Pt-HxMoO3 and keeps unchanged when the potential is set at 0.3 V (vs Hg-Hg2SO4) for 5 000 s in 1 mol/LCH3OH+0.5 mol/L U2SO4 solution. The results from energy dispersive spectroscopy show that the content of Nation in the composite is 0.57%. The results from scanning electron spectroscopy show that the composite of Nafion-Pt-HxMoO has a gain size of about 90 nm and distributes more uniformly than Pt-HxMoO3. 相似文献
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研究了助催化剂三氧化钨(WO3)对电解二氧化锰(EMD)催化性能的影响.通过球磨制备5种WO3含量的EMD复合催化剂,进行XRD、SEM和电化学性能测试.WO3影响了EMD的孔隙率,添加适量的WO3可改善EMD的催化性能.添加WO3催化剂的氧还原电位较未添加WO3催化剂提前0.02 V.当电压为-0.15 V时,EMD、( MnO2)33( WO3)0.7、(MnO2)33(WO3)1、( MnO2)33 (WO3)1.3及(MnO2 )33( WO3 )1.5的氧还原电流分别为:-0.21 mA、-0.35 mA、-0.85 mA、-0.53 mA和-0.08 mA,表明随着WO3添加量的增加,EMD的催化性能先提高,后下降.EMD、( MnO2)33( WO3 )0.7、( MnO2 )33( WO3)1、(MnO2)33 (WO3)1.3及(MnO2)33 (WO3)1.5制备的电池,放电平台分别为1.05 V、1.08 V、1.21 V、1.14 V和0.98 V;催化活性顺序为:(MnO2)33(WO3)1> (MnO2)33(WO3)1.3>(MnO2)33(WO3)0.7>EMD> (MnO2)33(WO3)1.5. 相似文献
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Nano-scale platinum catalysts were prepared on a glass carbon electrode by cyclic voltammetry. The surface morphology and active area of the catalysts, and their catalytic activity toward methanol oxidation and oxygen reduction were studied by SEM, linear and cyclic voltammetry. The result shows that the diameters of global Pt particles are affected by the scan rate of cyclic voltammetry: the faster the scan rate is, the smaller the diameters of Pt particles are. The size of the nano-scale platinum catalysts has different effects on their catalytic activity toward oxygen reduction and methanol oxidation: the catalyst with a size of 100 nm shows its best activity toward methanol oxidation, but the catalyst with a size of 65 nm shows its best activity toward oxygen reduction. 相似文献
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在180℃下通过改变K+与H+摩尔比使用水热法分别制备了δ-MnO2, α-MnO2和β-MnO2 纳米颗粒, K+与H+摩尔比分别为3.4、0.85和0.24。所合成的样品通过扫描电子显微镜(SEM), 粉末X射线衍射(XRD), 傅里叶变换红外光谱(FTIR), BET比表面分析, 热重分析(TG)和电化学方法表征。结果表明: K+与H+的浓度对产品的晶型、形貌以及比表面积有很大影响; 将这三种材料作为锌空电池的阴极材料时, δ-MnO2与α-MnO2的电化学性能明显优于β-MnO2. 在–0.35 V下, δ-MnO2、α-MnO2和β-MnO2的氧还原电流分别为56.28、56.01和40.88 mA/cm2。 相似文献
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