Electronic Effects of Nitrogen Atoms of Supports on Pt-Ni Rhombic Dodecahedral Nanoframes for Oxygen Reduction
Electronic Effects of Nitrogen Atoms of Supports on Pt-Ni Rhombic Dodecahedral Nanoframes for Oxygen Reduction
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DOI：
10.1021/acsaem.0c00903
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发表时间：
2020-07-27
影响因子：
6.4
通讯作者：
Yagi, Ichizo
中科院分区：
文献类型：
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作者：
Kato, Masaru;Nakahoshiba, Ryota;Yagi, Ichizo
碳载体上固定的铂基纳米结构作为电催化剂已得到广泛的应用。它们的催化活性可以通过包括氮掺杂和用含氮聚合物涂覆的载体改性来改善，其中氮原子可能在催化剂/载体界面处与表面Pt原子相互作用。为了了解氮掺杂和聚合物包覆的碳载体对Pt基纳米结构催化剂催化活性的电子效应，我们制备了以聚苯并咪唑（PBI）包覆和未包覆的碳纳米管为载体的Pt 3 Ni纳米框架（NF），用于氧还原反应（ORR），然后将它们与固定在氮掺杂和未掺杂碳载体上的NF的催化活性和电子性质进行了比较。虽然PBI涂层和氮掺杂的方法都提高了纳米纤维的催化活性，非原位X射线光电子能谱和原位X射线吸收光谱表明，氮掺杂对纳米纤维的电子效应，而PBI涂层显示几乎没有影响的电子状态的纳米纤维，但稳定Pt（OH）（ad）物种在电化学条件下。我们的研究表明，在催化剂/载体界面处的氮原子的微观环境的差异是高度敏感的Pt基电催化剂上的载体的电子效应。
Pt-based nanostructures immobilized on carbon supports have been widely used as electrocatalysts. Their catalytic activity can be improved by support modification including nitrogen doping and coating with nitrogen-containing polymers, where nitrogen atoms possibly interact with surface Pt atoms at a catalyst/support interface. To understand electronic effects of nitrogen-doped and polymer-coated carbon supports on the catalytic activity of Pt-based nanostructured catalysts, we prepared Pt3Ni nanoframes (NFs) supported on polybenzimidazole (PBI)-coated and uncoated carbon nanotubes for the oxygen reduction reaction (ORR), and then compared their catalytic activities and electronic properties with those of NFs immobilized on nitrogen-doped and undoped carbon supports. Although both PBI-coating and nitrogen-doping approaches improved the catalytic activity of NFs, ex situ X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy revealed that nitrogen doping showed electronic effects on NFs, whereas PBI-coating showed almost no impact on the electronic state of NFs but stabilized Pt(OH)(ad) species under electrochemical conditions. Our studies demonstrate that difference in microscopic environments of nitrogen atoms at the catalyst/support interface is highly sensitive to the electronic effects of supports on Pt-based electrocatalysts.