使用密度泛函理论深入了解 Pt/Au(111) 界面上乙醇电氧化的反应机制,Physical Chemistry Chemical Physics

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使用密度泛函理论深入了解 Pt/Au(111) 界面上乙醇电氧化的反应机制
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2022-10-21 , DOI: 10.1039/d2cp03186h
Tian Sheng ₁ , Han-Yue Wu ₁ , Xiao Lin ₂ , Wen-Feng Lin ₃

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了解乙醇电氧化反应动力学是开发直接乙醇燃料电池的基础。最近报道了使用二元 PtAu 催化剂作为增强乙醇电催化氧化的有效策略；然而，催化反应机制仍不清楚。在这项工作中，我们通过高能级密度泛函理论 (DFT) 计算，在原子水平上系统地研究了 Pt/Au(111) 模型表面上的乙醇电氧化反应机制；特别是分别考虑了具有不同表面原子排列的平坦 (111) 平台和阶梯式 (111) × (110) 和 (111) × (100) 界面。结果发现，对于乙醇解离，平坦的 (111) 平台比阶梯式 (111) × (110) 和 (111) × (100) 界面更活跃。阶梯式界面，vs. SHE (standard hydrogen electrode)，这对于与乙醇解离形成的CH ₃ CO* 中间体偶联生成乙酸作为乙醇电氧化反应的最终产物而不释放CO ₂具有重要意义。乙醇氧化形成 C1 产物的 C-C 键分裂过程非常有限。在相对于SHE高于 0.53 V 的电极电势下，平台位点可以促进乙醇分解和乙酸形成。我们的结果清楚地表明，对于乙醇电氧化反应，随着电极电位的增加，Pt/Au(111) 表面上的活性位点从阶梯式界面处的活性位点变为平坦平台位点。

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Insights into reaction mechanisms of ethanol electrooxidation at the Pt/Au(111) interfaces using density functional theory

Understanding ethanol electrooxidation reaction kinetics is fundamental to the development of direct ethanol fuel cells. The utilization of binary PtAu catalysts has been reported recently as an effective strategy to enhance ethanol electrocatalytic oxidation; however, the catalytic reaction mechanisms are still unclear. In this work, we systematically studied the ethanol electrooxidation reaction mechanisms on Pt/Au(111) model surfaces at an atomic level through high level density functional theory (DFT) calculations; particularly the flat (111) terrace and the stepped (111) × (110) and (111) × (100) interfaces with diverse surface atomic arrangements were considered, respectively. It was found that for ethanol dissociation, the flat (111) terrace is more active than the stepped (111) × (110) and (111) × (100) interfaces. The stepped interfaces, however, could activate water from the aqueous electrolyte solution to form adsorbed OH* at the electrode potential below 0.53 V vs. SHE (standard hydrogen electrode), which is of great importance in coupling with the CH₃CO* intermediate formed from ethanol dissociation to produce acetic acid as the final product of the ethanol electrooxidation reaction without releasing CO₂. The C–C bond splitting process for ethanol oxidation to form C1 products was very limited. The terrace sites can facilitate both ethanol decomposition and acetic acid formation at the electrode potential above 0.53 V vs. SHE. Our results clearly identify the fact that for ethanol electrooxidation reactions, with an increase in electrode potential, the active sites on Pt/Au(111) surfaces change from those at the stepped interfaces to the flat terrace sites.

更新日期：2022-10-21

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