Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland.
present address: College of Chemistry and Chemical Engineering, Hunan University, 410082, Changsha, China.
Chemphyschem. 2019 Nov 19;20(22):3154-3162. doi: 10.1002/cphc.201900193. Epub 2019 May 7.
In the present work we investigate the structure sensitivity of the oxygen evolution reaction (OER) combining electrochemistry, in situ spectroscopy and density functional theory calculations. The intrinsic difficulty of such studies is the fact that at electrode potentials where the OER is observed, the electrode material is highly oxidized. As a consequence, the surface structure during the reaction is in general ill-defined and only scarce knowledge exists concerning the structure-activity relationship of this important reaction. To alleviate these challenging conditions, we chose as starting point well-defined Pt single-crystal electrodes, which we exposed to well-defined conditioning before studying their OER rate. Using this approach, a potential region is identified where the OER on Pt is indeed structure-sensitive with Pt(100) being significantly more active than Pt(111). This experimental finding is in contrast to a DFT analysis of the adsorption strength of the reaction intermediates O*, OH*, and OOH* often used to plot the activity in a volcano curve. It is proposed that as a consequence of the highly oxidizing conditions, the structure-sensitive charge-transfer resistance through the interface determines the observed reaction rate.
在本工作中，我们结合电化学、原位光谱和密度泛函理论计算研究了析氧反应（OER）的结构敏感性。这类研究的固有难点在于，在观察到 OER 的电极电位下，电极材料高度氧化。因此，反应过程中的表面结构通常是不确定的，对于这一重要反应的结构-活性关系，我们仅有很少的了解。为了缓解这些具有挑战性的条件，我们选择了具有明确结构的 Pt 单晶电极作为起点，在研究它们的 OER 速率之前，对其进行了明确的预处理。通过这种方法，我们确定了一个 Pt 上的 OER 确实具有结构敏感性的电位区域，其中 Pt(100)比 Pt(111)的活性显著更高。这一实验发现与通常用于绘制火山曲线的反应中间体 O*、OH和 OOH的吸附强度的 DFT 分析结果相矛盾。我们提出，由于高度氧化的条件，通过界面的结构敏感电荷转移电阻决定了观察到的反应速率。
