Excavated octahedral Pt-Co alloy nanocrystals built with ultrathin nanosheets as superior multifunctional electrocatalysts for energy conversion applications
Excavated octahedral Pt-Co alloy nanocrystals built with ultrathin nanosheets as superior multifunctional electrocatalysts for energy conversion applications
复制标题
用超薄纳米片构建的挖掘八面体 Pt-Co 合金纳米晶体作为能量转换应用的卓越多功能电催化剂
DOI：
10.1016/j.nanoen.2017.07.041
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发表时间：
2017-09-01
期刊：
影响因子：
17.6
通讯作者：
Zheng, Lansun
中科院分区：
文献类型：
--
作者：
Chen, Qiaoli;Cao, Zhenming;Zheng, Lansun
Pt-Co合金被认为是众多铂系合金中最有潜力的电催化能量转换催化剂。为了优化性能和减少贵金属Pt的使用，需要同时考虑质量和表面贡献，这就要求Pt-Co合金纳米晶（NC）具有大的表面积和暴露的特定晶面。不幸的是，这些要求很难同时满足与正常的凸多面体形状的NC。在这项工作中，提出了一种简单的十六烷基三甲基溴化铵辅助的方法来可控地合成具有独特的挖掘八面体形状的Pt-Co合金NCs。挖掘的八面体Pt-Co合金NC本质上由相互垂直的交错的Pt-Co纳米片构建，所述纳米片与{100}面结合，所述{100}面对于面心立方金属不是最稳定的。独特的被挖掘的八面体PtCo合金NC的电化学表面积被确定为23.3 m（2）g（-1）Pt，这显著大于具有相同尺寸的正常八面体Pt2Co合金NC的电化学表面积（11.4 m（2）g（-1）Pt）。由于大的比表面积和高活性的{100}晶面的组合，挖掘的八面体PtCo NCs在碱性环境中对析氢反应显示出非凡的催化活性和耐久性。引人注目的是，在20 mA cm（-2）的电流密度下，挖掘的PtCo NC的过电位低至76.2 mV，这分别远低于{111}刻面Pt2Co NC（83.9 mV）和商业Pt/C（107 mV）的过电位。此外，当考虑质量和表面贡献时，挖掘八面体PtCo纳米碳对甲醇氧化反应和氧还原反应的电催化性能也有显著提高.
Pt-Co alloy is thought to be the best potential catalyst toward many electrocatalytic energy conversion reactions among various bimetallic alloys. To optimize the performance and reduce the usage of noble metal Pt, both the mass and surface contribution should be considered, which requires Pt-Co alloy nanocrystals (NCs) to possess large surface area and expose specific facets. Unfortunately, these requirements can hardly be met simultaneously for the NCs with normal convex polyhedral shapes. In this work, a simple cetyltrimethylammonium bromide-assisted method is proposed to controllably synthesize Pt-Co alloy NCs with a unique excavated octahedral shape. The excavated octahedral Pt-Co alloy NCs is intrinsically built with mutually perpendicular interlaced ultrathin PtCo nanosheets bound with {100} facets that are not the thermodynamically most stable for face-centered cubic metals. The electrochemically surface area of the unique excavated octahedral PtCo alloy NCs is determined to be 23.3 m(2) g(-1) Pt, which is significantly larger than that of the normal octahedral Pt2Co alloy NCs with the same size (11.4 m(2) g(-1) Pt). Owing to the combination of large surface area and high active {100} facets, the excavated octahedral PtCo NCs display extraordinary catalytic activity and durability towards hydrogen evolution reaction in alkaline environment. Strikingly, the overpotential of excavated PtCo NCs at the current density of 20 mA cm(-2) is as low as 76.2 mV, which is much lower than that for the {111} faceted Pt2Co NCs (83.9 mV) and the commercial Pt/C (107 mV), respectively. Besides, the excavated octahedral PtCo NCs also show significantly enhanced electrocatalytic performances towards methanol oxidation reaction and oxygen reduction reaction when both considering the mass and surface contribution.