Hydrogen evolution in acid solution at Pd electrodeposited onto Ti2AlC
Hydrogen evolution in acid solution at Pd electrodeposited onto Ti2AlC
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DOI：
10.1016/j.electacta.2016.12.015
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发表时间：
2017-01
影响因子：
6.6
通讯作者：
B. Jović;V. Jović;G. Branković;M. Radovic;N. Krstajić
中科院分区：
文献类型：
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作者：
B. Jović;V. Jović;G. Branković;M. Radovic;N. Krstajić
在0.5 M H2SO 4中，在25 °C下，以Ti 2AlC为基体，电沉积Pd，研究了Pd在Ti 2AlC上的析氢反应。采用脉冲电沉积技术，从不同浓度PdCl_2的1 M NH_4Cl溶液中在Ti_2Al_C上电沉积Pd。结果表明，在所有研究的解决方案，钯电沉积发生的扩散控制的三维成核和生长。采用极化曲线和电化学阻抗谱（EIS）对两种Pd镀层的HER进行了研究。用扫描电子显微镜（SEM）、X射线能谱（EDS）和原子力显微镜（AFM）对Pd样品的表面进行了表征。对于所有研究的样品，观察到HER的高催化活性。在20 mV下与饱和甘汞电极（SCE）电沉积5 s的Pd层（主要由孤立的半球形3D Pd中心和树枝晶组成（样品（2））记录到的Tafel斜率为−64 mV dec− 1，而对于理论厚度为1000 nm的Pd电沉积物（样品（1）），检测到的Tafel斜率为−143 mV dec− 1。所有的塔菲尔斜率记录的调查样品可以解释的福尔默-塔菲尔机制的HER假设Temkin吸附等温线，与步骤（Volmer或塔菲尔步骤）的速率决定之一。通过对EIS结果的分析，得出了两种方法的相似斜率。对于所有研究的样品，分别观察到log（RF）-1依赖性，而通过积分Pd氧化物还原的电荷获得的电化学活性表面积（EASA）被发现对于样品（1）是最高的。对于所有样品，呈现针对EASA校正的交换电流密度。
The hydrogen evolution reaction (HER) was studied in 0.5 M H2SO4at 25 °C on Pd electrodeposited onto Ti2AlC substrate, as an excellent substrate due to its high conductivity and high stability in concentrated sulfuric acid. Pd was electrodeposited onto Ti2AlC by pulse technique from the solutions containing different concentrations of PdCl2in 1 M NH4Cl. It was shown that in all investigated solutions Pd electrodeposition occurs by the diffusion-controlled 3D nucleation and growth. Two types of Pd electrodeposits were submitted to the study of the HER by the polarization measurements and the electrochemical impedance spectroscopy (EIS). The surface of Pd samples was characterized by scanning electron microscopy (SEM), by energy dispersive X-ray spectroscopy (EDS) and by atomic force microscopy (AFM). High catalytic activity for the HER was observed for all investigated samples. The Tafel slope of −64 mV dec−1was recorded for the Pd layer electrodeposited at 20 mV vs. saturated calomel electrode (SCE) for 5 s, mainly composed of isolated hemispherical 3D Pd centers and dendrites (sample(2)), while for Pd electrodeposit with the theoretical thickness of 1000 nm (sample(1)) Tafel slope of −143 mV dec−1was detected. All Tafel slopes recorded for the investigated samples could be explained by the Volmer-Tafel mechanism for the HER assuming Temkin adsorption isotherm, with either of the steps (Volmer or Tafel step) being the rate-determining one. By the analysis of the EIS results similar slopes for theEvs. log (RF)−1dependences were observed for all investigated samples respectively, while the electrochemically active surface area (EASA), obtained by the integration of the charge for Pd-oxide reduction was found to be the highest for the sample(1). The exchange current densities corrected for the EASA were presented for all samples.