Hydrazine Oxidation at Porous and Preferentially Oriented {100} Pt Thin Films
Hydrazine Oxidation at Porous and Preferentially Oriented {100} Pt Thin Films
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DOI：
10.1007/s12678-012-0122-1
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发表时间：
2013-06-01
期刊：
影响因子：
3.1
通讯作者：
Guay, D.
中科院分区：
文献类型：
--
作者：
Roy, C.;Bertin, E.;Guay, D.
Pt 薄膜由 0.25 x 10(-3) M Na2PtCl6 中心点 6H(2)O 和 1.0 x 10(-2) M HCl 溶液电沉积在 Ti 基底上，沉积电位 E (d) 相对于饱和甘汞电极 (SCE) 为 -0.35 V，不含任何表面活性剂。这些薄膜在 0.5 M H2SO4 中的循环伏安图表现出高度取向的 (100) Pt 表面的特征。结果表明，随着沉积电荷 Q (d) 从 1 C cm(-2) 增加到 3 C cm(-2)，根据 h (2)/h (1) 比率确定的 (100) 表面位点分数从 1.35 变化到 1.81。当 Q (d) > 3.0 C cm(-2) 时，h (2)/h (1) 比率保持恒定，接近 1.7。相反，随着Q(d)从1增加到176 C cm(-2)，沉积的Pt薄膜的粗糙度因子从4连续增加到423。 Pt 的电沉积速率通过电化学石英微量天平测量，作为 Pt 盐浓度和沉积电势的函数。发现这两个参数对 (100) 表面位点的出现具有深远的影响。在最佳沉积条件下（0.25 x 10(-3) M Na2PtCl6 中心点 6H(2)O，1.0 x 10(-2) M HCl，E (d) = -0.35 V vs. SCE，Q (d) = 176 C cm(-2)），粗糙度因子高达 423，约实现了 45% 的 (100) Pt 表面原子。在 50 mM N2H4 和 0.5 M 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增加。在相对于 SCE 0.20 V 的长期（5 小时）电解过程中，与多晶 Pt 相比，优先取向（100）Pt 表面的电催化活性增强了 2 倍。
Pt thin films were electrodeposited on a Ti substrate from a 0.25 x 10(-3) M Na2PtCl6 center dot 6H(2)O and 1.0 x 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 similar to 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 x 10(-3) M Na2PtCl6 center dot 6H(2)O, 1.0 x 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.