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首页> 外文期刊>ACS applied materials & interfaces >Metal-Support Interaction in Platinum and Palladium Nanoparticles Loaded on Nitrogen-Doped Mesoporous Carbon for Oxygen Reduction Reaction
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Metal-Support Interaction in Platinum and Palladium Nanoparticles Loaded on Nitrogen-Doped Mesoporous Carbon for Oxygen Reduction Reaction

机译：负载氮掺杂介孔碳上的铂和钯纳米粒子中的金属-载体相互作用用于氧还原反应

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摘要

Mesoporous carbons are highly porous materials, which show large surface area, chemical inertness and electrochemical performances superior to traditional carbon material. In this study, we report the preparation of nitrogen-doped and undoped mesoporous carbons by an optimized hard template procedure employing silica as template, sucrose and ammonia as carbon and nitrogen source, respectively. Surface area measurements assert a value of 900 and 600 m(2) g1 for the best doped and undoped samples, respectively. Such supports were then thoroughly characterized by surface science and electron microscopy tools. Afterward, they were decorated with Pt and Pd nanoparticles, and it was found that the presence of nitrogen defects plays a significant role in improving the metal particles dimension and dispersion. In fact, when doped supports are used, the resulting metal nanoparticles are smaller (24 nm) and less prone to aggregation. Photoemission measurements give evidence of a binding energy shift, which is consistent with the presence of an electronic interaction between nitrogen atoms and the metal nanoparticles, especially in the case of Pd. The catalytic properties of electrodes decorated with such catalyst/support systems were investigated by linear sweep voltammetry and by rotating disk electrode measurements, revealing excellent stability and good activity toward oxygen reduction reaction (ORR). In particular, although Pd nanoparticles always result in lower activity than Pt ones, both Pt and Pd electrodes based on the N-doped supports show an increased activity toward ORR with respect to the undoped ones. At the same mass loading, the Tafel slope and the stability test of the Pt@N-doped electrocatalysts indicate superior performances to that of a commercial Pt@C catalysts (30 wt % Pt on Vulcan XC-72, Johnson Matthey).
机译：中孔碳是高度多孔的材料，与传统的碳材料相比，它具有较大的表面积，化学惰性和电化学性能。在这项研究中，我们报告了通过优化的硬模板程序分别使用二氧化硅作为模板，蔗糖和氨作为碳源和氮源来制备氮掺杂和未掺杂的介孔碳。表面积测量得出最佳掺杂和未掺杂样品的值分别为900和600 m（2）g1。然后通过表面科学和电子显微镜工具对此类支撑物进行全面表征。之后，用Pt和Pd纳米颗粒装饰它们，发现氮缺陷的存在在改善金属颗粒的尺寸和分散性方面起着重要作用。实际上，当使用掺杂的载体时，所得的金属纳米粒子较小（24 nm），并且较不易于聚集。光发射测量提供了结合能移动的证据，这与氮原子和金属纳米粒子之间存在电子相互作用相一致，尤其是在Pd的情况下。通过线性扫描伏安法和旋转圆盘电极测量研究了用这种催化剂/载体系统装饰的电极的催化性能，显示出优异的稳定性和良好的抗氧还原反应活性。特别地，尽管Pd纳米颗粒总是导致活性低于Pt纳米颗粒，但是基于N掺杂载体的Pt和Pd电极相对于未掺杂纳米颗粒都显示出对ORR的增强活性。在相同质量负载下，Pt @ N掺杂电催化剂的Tafel斜率和稳定性测试表明其性能优于商用Pt @ C催化剂（在Vulcan XC-72上为30 wt％Pt，Johnson Matthey）。

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