Electron penetration from metal core to metal species attached skin in nitrogen-doped core-shell catalyst for enhancing oxygen evolution reaction
Electron penetration from metal core to metal species attached skin in nitrogen-doped core-shell catalyst for enhancing oxygen evolution reaction
复制标题
氮掺杂核壳催化剂中从金属核到金属物质附着表层的电子渗透增强析氧反应
DOI：
10.1016/j.electacta.2019.134939
复制
发表时间：
2019-12-10
影响因子：
6.6
通讯作者：
Wei, Zidong
中科院分区：
文献类型：
--
作者：
Najam, Tayyaba;Shah, Syed Shoaib Ahmad;Wei, Zidong
金属纳米颗粒包覆在氮掺杂碳中是提高催化活性的有效途径，但其机理尚存在争议。本文采用模板纳米铸造法制备了金属氮掺杂碳屏蔽（Me-NC）NiFe纳米粒子（NiFe-NC/Me-NC），然后选择性地去除表面金属物种或破坏核壳结构，研究金属核或金属掺杂表面对活性增强的作用。我们首次表明，协同效应与电子从金属掺杂的NC壳到金属核的渗透一起导致表面催化反应的增强。核/壳结构使金属核与电解质绝缘，并且金属核充当电子受体以改变表面电子结构。电化学测试表明，NiFe-NC/Me-NC具有较高的电催化活性，在231 mV和271 mV的过电位下，其析氧和析氢电流密度均为10 mA cm-2，且在碱性介质中具有良好的稳定性。而球磨后核壳结构被破坏的NiFe-NC/Me-NC样品和酸浸后表面金属NPs被去除的样品均显示出显著降低的活性，证实了NPs核和Me-NC-片之间的协同效应对于有效的催化性能。(C)2019由Elsevier Ltd.出版
Metal nanoparticles (NPs) encapsulated into nitrogen-doped carbon are proved to be an efficient way to enhance the catalytic activity, but the mechanism behind is still debatable. Here, we prepared metal-nitrogen doped carbon shield (Me-NC) NiFe nanoparticles (NiFe-NC/Me-NC) by simple template nano-casting, and then selectively removed metal species on the surface or destroyed the core-shell structure to investigate whether the metal core or the metal doped surface are responsible for the activity enhancement. We show that, for the first time, a synergistic effect together with the electron penetration from metal doped NC shell to metal core is responsible for the enhancement of surface catalytic reaction. The core/shell structure insulates the metal core from electrolyte and the metal core act as electron receptor to modify the surface electronic structure. The electrochemical evaluations show that the as-synthesized NiFe-NC/Me-NC exhibits high electrocatalytic activity, which affords the current density of 10 mA cm(-2) at low overpotentials of 231 mV and 271 mV for oxygen and hydrogen evolution reactions as well as excellent stability in alkaline medium. While both the NiFe-NC/Me-NC sample after ball-milled with the core-shell structure destroyed and the sample after acid leached with surface metal NPs removed show a remarkably decreased activity, confirming the synergistic effect between NPs core and Me-NC-sheet for efficient catalytic performance. (C) 2019 Published by Elsevier Ltd.