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首页> 外文期刊>Electrocatalysis >Hydrazine Oxidation at Porous and Preferentially Oriented {100} Pt Thin Films
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Hydrazine Oxidation at Porous and Preferentially Oriented {100} Pt Thin Films

机译：多孔和优先取向的{100} Pt薄膜上的肼氧化

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摘要

Pt thin films were electrodeposited on a Ti substrate from a 0.25 × 10−3 M Na2PtCl6 · 6H2O and 1.0 × 10−2 M HCl solution at a deposition potential, E d , of −0.35 V vs. saturated calomel electrode (SCE), without any surfactants. The cyclic voltammograms of these films in 0.5 M H2SO4 exhibit the characteristic features of highly oriented (100) Pt surface. It is shown that the fraction of (100) surface sites, as determined from the h 2/h 1 ratio, varies from 1.35 to 1.81 as the deposition charge, Q d , increases from 1 to 3 C cm−2. For Q d  > 3.0 C cm−2, the h 2/h 1 ratio stays constant at ~1.7. In contrast, there is a continuous increase of the roughness factor of the deposited Pt films from 4 to 423 as Q d is increased from 1 to 176 C cm−2. The electrodeposition rates of Pt were measured by means of an electrochemical quartz microbalance as a function of the Pt salt concentration and of the deposition potential. Both parameters were found to have a profound influence on the occurrence of the (100) surface sites. In the optimum deposition conditions (0.25 × 10−3 M Na2PtCl6 · 6H2O, 1.0 × 10−2 M HCl, E d  = −0.35 V vs. SCE and Q d  = 176 C cm−2), roughness factor as large as 423 with ca. 45 % of (100) Pt surface atoms were achieved. The electrocatalytic properties of these films were assessed in presence of 50 mM N2H4 and in 0.5 M H2SO4 aqueous solution. The presence of a large fraction of (100) Pt surface sites lead to a significant increase of the electrocatalytic activity of these films compared to polycrystalline Pt surfaces. During long-term (5 h) electrolysis at 0.20 V vs. SCE, there is a factor of 2 enhancement of the electrocatalytic activity of preferentially oriented (100) Pt surface as compared to polycrystalline Pt.
机译：在0.25×10-3 M Na2PtCl6·6H2O和1.0×10-2 M HCl溶液中以相对于饱和甘汞电极（SCE）为-0.35V的沉积电势E d将Pt薄膜电沉积在Ti衬底上，没有任何表面活性剂。这些膜在0.5M H2SO4中的循环伏安图显示了高取向（100）Pt表面的特征。结果表明，随着沉积电荷Q d从1增加到3 C cm-2，从h 2 / h 1比率确定的（100）表面部位的分数在1.35到1.81之间变化。对于Q d 3.0 C cm-2，h 2 / h 1比保持恒定在〜1.7。相反，随着Q d从1增大到176 C cm-2，沉积的Pt膜的粗糙度因子从4连续增加到423。借助于电化学石英微量天平，根据Pt盐浓度和沉积电位测量Pt的电沉积速率。发现这两个参数对（100）个表面位点的发生具有深远的影响。在最佳沉积条件下（0.25×10-3 M Na2PtCl6·6H2O，1.0×10-2-2 M HCl，E d = -0.35V vs. SCE和Q d = 176C cm-2），粗糙度系数高达423与约。 （100）铂表面原子达到了45％。在50mM N2H4和0.5M H2SO4水溶液中评估这些薄膜的电催化性能。与多晶Pt表面相比，大部分（100）Pt表面位点的存在导致这些薄膜的电催化活性显着提高。在0.20 V vs. SCE下长期（5 h）电解过程中，与多晶Pt相比，优先取向（100）Pt表面的电催化活性提高了2倍。

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