Understanding the role of mass transport in tuning the hydrogen evolution kinetics on gold in alkaline media
Understanding the role of mass transport in tuning the hydrogen evolution kinetics on gold in alkaline media
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DOI：
10.1063/5.0064330
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发表时间：
2021-10-07
影响因子：
4.4
通讯作者：
Koper, Marc T. M.
中科院分区：
文献类型：
--
作者：
Goyal, Akansha;Koper, Marc T. M.
在这项工作中，我们提出了一个深入的研究质量传输条件的作用，在调整的析氢动力学的金通过旋转速率控制。有趣的是，我们发现，析氢反应（HER）活性随电极旋转速率的增加而降低。当我们增加旋转（质量传输）速率时，局部产生的氢氧根离子（2 H（2）O +2 e（-）&RARR; H-2 + 2 OH（-））以加速的速率从电极表面传输出去。这导致局部pH值降低，并且由于需要满足局部电中性，降低了近表面阳离子浓度。近表面阳离子浓度的降低导致HER的抑制，这是因为表面附近的阳离子在稳定用于速率决定Volmer步骤（*H-OH delta-cat（+））的过渡态方面起着中心作用。此外，我们提出了一个详细的分析模型，定性捕捉所观察到的质量输运依赖HER完全基于电中性的原则。最后，我们还将HER对金（Li+ < Na+ < K+）的阳离子身份依赖性与双电层中阳离子有效浓度的变化及其溶剂化能的变化相关联。
In this work, we present an in-depth study of the role of mass transport conditions in tuning the hydrogen evolution kinetics on gold by means of rotation rate control. Interestingly, we find that the hydrogen evolution reaction (HER) activity decreases with the increasing rotation rate of the electrode. As we increase the rotation (mass transport) rate, the locally generated hydroxyl ions (2H(2)O +2e(-) & RARR; H-2 + 2OH(-)) are transported away from the electrode surface at an accelerated rate. This results in decreasing local pH and, because of the need to satisfy local electroneutrality, decreasing near-surface cation concentration. This decrease in the near-surface cation concentration results in the suppression of HER. This is because the cations near the surface play a central role in stabilizing the transition state for the rate determining Volmer step (*H-OH delta--cat(+)). Furthermore, we present a detailed analytical model that qualitatively captures the observed mass transport dependence of HER solely based on the principle of electroneutrality. Finally, we also correlate the cation identity dependence of HER on gold (Li+ < Na+ < K+) to the changes in the effective concentration of the cations in the double layer with the changes in their solvation energy.