First Principles Simulations of Cyclic Voltammograms on Stepped Pt(553) and Pt(533) Electrode Surfaces
First Principles Simulations of Cyclic Voltammograms on Stepped Pt(553) and Pt(533) Electrode Surfaces
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DOI：
10.1002/celc.201600293
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发表时间：
2016-10-01
期刊：
影响因子：
4
通讯作者：
Janik, Michael J.
中科院分区：
文献类型：
--
作者：
McCrum, Ian T.;Janik, Michael J.
密度泛函理论（DFT）计算被用来检查氢和氢氧化物的吸附阶梯Pt（553）和Pt（533）表面，并模拟相关的循环伏安在碱性和酸性电解质。氢和氢氧化物表面物种是许多重要电催化反应的活性中间体或旁观物种，如氢氧化、氧还原和甲醇氧化。我们研究了氢，氢氧化物，水，和钠阳离子上的阶梯铂表面，Pt（553）和Pt（533）的吸附。由于氢和氢氧化物（与共吸附水）在Pt（553）和Pt（533）台阶上的强吸附，它们将在低电位下竞争吸附在台阶上。共吸附钠的存在下，附近的步骤削弱了溶剂化的氢氧化物的吸附，我们确定为一个可能的原因的非能斯特位移的尖锐的步骤相关的峰从酸性到碱性电解质的变化。我们还研究了氢在Pt（553）和Pt（533）平台上的吸附，并模拟了Pt（553）和Pt（533）平台上的低电位循环伏安图。实验伏安图被很好地表示为台阶和平台特征的总和，并且（553）和（533）循环伏安特征非常类似于来自匹配局部原子排列的低指数（111）、（100）和（110）表面小面的那些特征。
Density functional theory (DFT) calculations are used to examine hydrogen and hydroxide adsorption on stepped Pt(553) and Pt(533) surfaces and to simulate the associated cyclic voltammograms in both basic and acidic electrolytes. Hydrogen and hydroxide surface species are active intermediates or spectator species in many important electrocatalytic reactions, such as hydrogen oxidation, oxygen reduction, and methanol oxidation. We examine the adsorption of hydrogen, hydroxide, water, and a sodium cation onto the stepped platinum surfaces, Pt(553) and Pt(533). Owing to the strong adsorption of both hydrogen and hydroxide (with co-adsorbed water) at the steps of Pt(553) and Pt(533), they will competitively adsorb on the step at low potentials. The presence of co-adsorbed sodium near the step weakens the adsorption of solvated hydroxide, which we identify as a possible cause of the non-Nernstian shift of the sharp step-associated peaks in changing from acidic to basic electrolytes. We also examine hydrogen adsorption at the terrace of Pt(553) and Pt(533), and simulate a low-potential cyclic voltammogram on Pt(553) and Pt(533). The experimental voltammogram is well-represented as a sum of step and terrace features, and the (553) and (533) cyclic voltammetry features closely resemble those from the low-index (111), (100), and (110) surface facets that match the local atom arrangements.