Direct 12-Electron Oxidation of Ethanol on a Ternary Au(core)-PtIr(Shell) Electrocatalyst
Direct 12-Electron Oxidation of Ethanol on a Ternary Au(core)-PtIr(Shell) Electrocatalyst
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DOI：
10.1021/jacs.9b03474
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发表时间：
2019-06-19
影响因子：
15
通讯作者：
Wang, Jia X.
中科院分区：
文献类型：
--
作者：
Liang, Zhixiu;Song, Liang;Wang, Jia X.
了解金属和原子结构在激活电催化反应的各个基本步骤中的作用可以帮助合理设计二元或三元催化剂，从而通过有利的途径促进对所需产物的活性。在这里，我们报道了一种新开发的三元Au@PtIr核壳催化剂，用于碱性溶液中的乙醇氧化反应（EOR），与AuPtIr合金催化剂相比，其活性提高了6个数量级。对 Au@PtIr 及其双金属子集 Au@Pt 和 PtIr 合金的原位红外反射吸收光谱分析发现，PtIr 上的单原子步骤和 Au 诱导的拉伸应变通过乙醇解离吸附促进 C-C 键分裂，Ir 促进低电位下的脱氢。正如仅在对乙醇解离吸附相当不活跃的 PtIr 合金中观察到的 CO 带所证明的那样，我们提出在 EOR 的最早阶段分裂 C-C 键会激活直接的 12 电子完全氧化途径，因为富氢碎片可以在没有 CO 作为中毒中间体的情况下完全氧化。 Au 核心和表面 Ir 互补效应的协同作用使 Au PtIr 在 EOR 方面具有出色的性能，其特点是 0.3 V 的低起始电位和 8.3 A mg（全金属）(-1) 峰值电流，其中 57% 的电流通过乙醇完全氧化产生。
Understanding the roles of metals and atomic structures in activating various elementary steps of electro-catalytic reactions can help rational design of binary or ternary catalysts for promoting activity toward desirable products via favorable pathways. Here we report on a newly developed ternary Au@PtIr core-shell catalyst for ethanol oxidation reaction (EOR) in alkaline solutions, which exhibits an activity enhancement of 6 orders of magnitude compared to AuPtIr alloy catalysts. Analysis of in situ infrared reflection absorption spectra for Au@PtIr and its bimetallic subsets, Au@Pt and PtIr alloy, found that monatomic steps and Au-induced tensile strain on PtIr facilitate C-C bond splitting via ethanol dissociative adsorption and Ir promotes dehydrogenation at low potentials. As evidenced by the CO band being observed only for the PtIr alloy that is rather inactive for ethanol dissociative adsorption, we propose that splitting the C-C bond at the earliest stage of EOR activates a direct 12-electron full oxidation pathway because hydrogen-rich fragments can be fully oxidized without CO as a poisoning intermediate. The resulting synergy of complementary effects of Au core and surface Ir leads to an outstanding performance of Au PtIr for EOR as characterized by a low onset potential of 0.3 V and 8.3 A mg(all-metals)(-1) peak current with 57% currents generated via full ethanol oxidation.