Department of Chemistry , Wayne State University , Detroit , Michigan 48202 , United States.
College of Chemistry, Chemical Engineering and Biotechnology , Donghua University , Shanghai 201620 , China.
Langmuir. 2018 Apr 17;34(15):4554-4559. doi: 10.1021/acs.langmuir.8b00435. Epub 2018 Apr 4.
We report the correlation between H gas bubble formation potential and hydrogen evolution reaction (HER) activity for Au and Pt nanodisk electrodes (NEs). Microkinetic models were formulated to obtain the HER kinetic information for individual Au and Pt NEs. We found that the rate-determining steps for the HER at Au and Pt NEs were the Volmer step and the Heyrovsky step, respectively. More interestingly, the standard rate constant ( k) of the rate-determining step was found to vary over 2 orders of magnitude for the same type of NEs. The observed variations indicate the HER activity heterogeneity at the nanoscale. Furthermore, we discovered a linear relationship between bubble formation potential ( E) and log( k) with a slope of 125 mV/decade for both Au and Pt NEs. As log ( k) increases, E shifts linearly to more positive potentials, meaning NEs with higher HER activities form H bubbles at less negative potentials. Our theoretical model suggests that such linear relationship is caused by the similar critical bubble formation condition for Au and Pt NEs with varied sizes. Our results have potential implications for using gas bubble formation to evaluate the HER activity distribution of nanoparticles in an ensemble.
我们报告了 H 气泡形成潜力与金和铂纳米盘电极 (NE) 析氢反应 (HER) 活性之间的相关性。我们制定了微观动力学模型来获取单个 Au 和 Pt NE 的 HER 动力学信息。我们发现 Au 和 Pt NE 上 HER 的速控步骤分别为 Volmer 步骤和 Heyrovsky 步骤。更有趣的是，对于相同类型的 NE，速率决定步骤的标准速率常数 (k) 变化超过 2 个数量级。观察到的变化表明在纳米尺度上 HER 活性具有异质性。此外，我们发现气泡形成潜力 (E) 与 log(k) 之间存在线性关系，对于 Au 和 Pt NE，斜率为 125 mV/decade。随着 log(k) 的增加，E 线性地向更正的电势移动，这意味着具有更高 HER 活性的 NE 在更小的负电势下形成 H 气泡。我们的理论模型表明，这种线性关系是由具有不同尺寸的 Au 和 Pt NE 的相似临界气泡形成条件引起的。我们的结果对于使用气泡形成来评估纳米颗粒在整体中的 HER 活性分布具有潜在意义。
