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薄壳层核壳型Ni/Pt纳米粒子的制备及电催化性能 总被引:1,自引:0,他引:1
通过胶体-化学镀法制备不同厚度薄壳层核壳型Ni/Pt纳米粒子, 采用HRTEM、EDS、XPS和XRD手段对粒子的形貌、晶型和组成进行物理表征. 采用动电位、循环伏安法对其氧电还原和甲醇电氧化活性进行测试. 实验结果表明, 核壳结构Ni/Pt纳米颗粒基本为球形, 其中Ni1-Pt0.067平均直径为7 nm左右, 壳层厚度约1 nm. 与Pt/C相比, 核壳型Ni/Pt纳米粒子对氧电还原和甲醇电氧化的催化活性显著提高. 在所制备的不同壳层厚度催化剂中, Ni1-Pt0.067/C在0.5 mol/L H2SO4中氧电还原的最大峰电流密度可达到143.06 mA/mg, 是相同反应条件Pt/C峰电流密度的1.4倍; 而Ni1-Pt0.067/C在0.5 mol/L H2SO4+1.0 mol/L CH3OH溶液中甲醇电氧化峰电流密度可达538.3 mA/mg, 是Pt/C峰电流密度的5.2倍. 若以1 mg贵金属Pt为基准, Ni1-Pt0.067/C的比质量活性相对Pt/C的提高了30倍. 相似文献
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Polarization data of BH-4 oxidation on Cu anode in alkaline solution were measured at steady state by a self-made experimental cell. The experimental polarization curve showed three regions:the region at lower over-potential η(below 0.4 V approximately),the region at higher η(above 0.6 V approximately)and the transitional region at medium η. It was found that the limiting current density is caused by the limiting elemental step rather than the external mass transport. The apparent reaction order with respect to BH-4 changes from 0 to 1. The active energy is about 40 kJ·mol-1 in both regions with lower and higher η,and is higher than 40 kJ·mol-1 in the transitional region. With the experimental temperatures and NaOH concentration,the hydrogen production rates released by the electrode reaction were measured at [BH-4]/[OH-]ratios of 1∶40,1∶20,1∶6. 7 and 1∶4,which is strongly dependent on the over-potential. The apparent number of released electron n by the reaction was calculated by using the measured amounts of hydrogen and coulomb. Higher value of n was obtained at lower [BH-4]/[OH-]ratio,higher temperature as well as higher over-potential. Under the experimental conditions,the value of n varies from 0 to 7,while in the transitional region it is just in the range of 3 to 5. The experimental results indicate that the limiting current density or n value will increase by virtue of proper experimental conditions. However,to considerably increase the current density at lower over-potential requires a modified anode with higher activity. 相似文献
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用化学还原法制备了M/C(M=Pt, Pd, Ni, Ag, Au) 5种纳米金属碳截催化剂,用XRD、XPS分别表征活性物的晶相结构、表面组成和价态形式,用TEM观察催化剂微观形貌,用循环伏安法测定不同催化剂对甲醇氧化的电催化活性。结果表明,催化剂中的纳米金属粒径在3~11 nm之间,纯度较高,在载体表面的分布较为均匀;Pd/C催化剂对甲醇氧化有较好的催化作用,Ni/C对甲醇氧化有一定的活性,而Ag/C和Au/C几乎没有活性。在1 mol·L-1CH3OH+1 mol·L-1NaOH条件下,Pd/C对甲醇氧化最高峰电流密度为890 mA·mg-1,约为Pt/C的66%,Ni/C对甲醇氧化最高峰电流密度为6.3 mA·mg-1,仅为Pt/C的0.46%。 相似文献
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采用脉冲电沉积法制备了碳载的Pt-Ru-Ho电催化剂,循环伏安法(CV)和交流阻抗法(EIS)测定催化剂的甲醇电氧化活性,用XRD、EDS和XPS表征电催化剂的物性结构、表面元素组成和价态形式.结果表明,电催化剂中Pt,Ru,H0 3种元素以合金的形式存在,在合金表面有HoO存在,合金微粒粒径为3.5 nm,比表面积为73.3 m2.g-1;掺杂适量稀土金属Ho对Pt-Ru合金的活性有明显影响,其中原子比为npt:nRu:nHo=1:1:0.2时,Pt-Ru-Ho/C中Ho的含量较为适宜,电催剂的Tafel常数α减小,反应活化能低于Pt-Ru/C,为28.4 kJ·mol-1,催化活性明显高于Pt-Ru/C,但Ho含量过高Pt-Ru-Ho/C的活性低于Pt-Ru/C:Pt-Ru-Ho0 .2/C甲醇的反应级数为0.17级. 相似文献
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