A Study of the Mechanism of the Hydrogen Evolution Reaction on Nickel by Surface Interrogation Scanning Electrochemical Microscopy
A Study of the Mechanism of the Hydrogen Evolution Reaction on Nickel by Surface Interrogation Scanning Electrochemical Microscopy
复制标题
表面询问扫描电化学显微镜研究镍析氢反应机理
DOI：
10.1021/jacs.7b00279
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发表时间：
2017-04-05
影响因子：
15
通讯作者：
Bard, Allen J.
中科院分区：
文献类型：
--
作者：
Liang, Zhenxing;Ahn, Hyun S.;Bard, Allen J.
采用扫描电化学显微镜研究了两种工作模式下碱性介质中镍的析氢反应。首先，采用基板生成/尖端收集模式从极化曲线中的总电流中提取与HER相关的“真实”阴极电流。与金属Ni相比，低价态Ni氧化物的存在提高了HER的电催化活性。这一结果是在协议与先前的主张，解离吸附的水可以增强在Ni/Ni氧化物界面。其次，表面询问扫描电化学显微镜（SI-SECM）模式被用来直接测量在给定的电位下的吸附氢在Ni上的覆盖度。模拟表明，氢覆盖率遵循Frumkin等温线相对于所施加的电位。结合Tafel斜率和表面氢覆盖率的分析，提出了在所研究的电位窗口内，氢的吸附（Volmer步骤）是反应速率的决定步骤.
The hydrogen evolution reaction (HER) on Ni in alkaline media was investigated by scanning electrochemical microscopy under two operating modes. First, the substrate generation/tip collection mode was employed to extract the "true" cathodic current associated with the HER from the total current in the polarization curve. Compared to metallic Ni, the electrocatalytic activity of the HER is improved in the presence of the low-valence-state oxide of Ni. This result is in agreement with a previous claim that the dissociative adsorption of water can be-enhanced at the Ni/Ni oxide interface. Second, the surface interrogation scanning electrochemical microscopy (SI-SECM) mode was used to directly measure the coverage of the adsorbed hydrogen on Ni at given potentials. Simulation indicates that the hydrogen coverage follows a Frumkin isotherm with respect to the applied potential. On the basis of the combined analysis of the Tafel slope and surface hydrogen coverage, the rate determining step is suggested to be the adsorption of hydrogen (Volmer step) in the investigated potential window.