Enhanced Electrocatalytic Oxidation of Small Organic Molecules on Platinum-Gold Nanowires: Influence of the Surface Structure and Pt-Pt/Pt-Au Pair Site Density
Enhanced Electrocatalytic Oxidation of Small Organic Molecules on Platinum-Gold Nanowires: Influence of the Surface Structure and Pt-Pt/Pt-Au Pair Site Density
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DOI：
10.1021/acsami.1c17244
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发表时间：
2021-12-10
影响因子：
9.5
通讯作者：
Koenigsmann, Christopher
中科院分区：
文献类型：
--
作者：
Smina, Nicole;Rosen, Adam;Koenigsmann, Christopher
甲醇、葡萄糖等有机小分子的电化学氧化是一个重要的过程，在燃料电池和传感器等领域有着广泛的应用。SOM氧化中的一个关键挑战是表面被一氧化碳（CO）和其他部分氧化的中间体毒化，这归因于Pt-Pt对位点的存在。克服这一挑战的一个有前途的途径是开发催化剂，通过“直接”途径选择性氧化SOM，不形成CO作为主要中间体。在这份报告中，我们利用环境，模板为基础的方法来制备PtAu合金纳米线与可调组合物。X射线光电子能谱测量表明，表面组成相匹配的合成后的散装组合物。Monte Carlo方法模拟的Pt Au合金的表面结构与不同的覆盖度的氧吸附物和不同程度的氧吸附强度显示，在电化学条件下的氧吸附富集的表面与Pt和大部分的Pt-Pt网站保留在表面上，即使与Au的含量高达50%。Pt Au纳米线对甲醇和葡萄糖氧化的电化学性质和催化性能的测量表明，通过添加相对少量的Au（类似于10%）来抑制产生CO的机理途径，并且50%的Au可以完全抑制CO的形成。用少量的Au抑制CO的形成表明Pt-Au对位点的存在可能在确定SOM氧化的机制中比Pt-Pt对位点密度更重要。
The electrochemical oxidation of small organic molecules (SOMs) such as methanol and glucose is a critical process and has relevant applications in fuel cells and sensors. A key challenge in SOM oxidation is the poisoning of the surface by carbon monoxide (CO) and other partially oxidized intermediates, which is attributed to the presence of Pt-Pt pair sites. A promising pathway for overcoming this challenge is to develop catalysts that selectively oxidize SOMs via "direct" pathways that do not form CO as a primary intermediate. In this report, we utilize an ambient, template-based approach to prepare PtAu alloy nanowires with tunable compositions. X-ray photoelectron spectroscopy measurements reveal that the surface composition matches that of the bulk composition after synthesis. Monte Carlo method simulations of the surface structure of PtAu alloys with varying coverage of oxygen adsorbates and varying degrees of oxygen adsorption strength reveal that oxygen adsorption under electrochemical conditions enriches the surface with Pt and a large fraction of Pt-Pt sites remain on the surface even with the Au content of up to 50%. Electrochemical properties and the catalytic performance measurements of the PtAu nanowires for the oxidation of methanol and glucose reveal that the mechanistic pathways that produce CO are suppressed by the addition of relatively small quantities of Au (similar to 10%), and CO formation can be completely suppressed by 50% Au. The suppression of CO formation with small quantities of Au suggests that the presence of Pt-Au pair sites may be more important in determining the mechanism of SOM oxidation rather than Pt-Pt pair site density.