Zhao Jian-Qiang, Cai Dandan, Dai Jun, Kurmoo Mohamedally, Peng Xu, Zeng Ming-Hua
Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, Department of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China.
Institut de Chimie de Strasbourg, CNRS-UMR7177, Université de Strasbourg, 67070 Strasbourg Cedex, France.
Sci Bull (Beijing). 2019 Nov 30;64(22):1667-1674. doi: 10.1016/j.scib.2019.09.013. Epub 2019 Sep 13.
The development of efficient oxygen evolution reaction (OER) catalysts is still lacking in exploration of the mechanism of controlled pyrolysis of precursors among new material platforms. Here, a novel Co-based coordination molecular cluster has been first introduced as precursor to obtain metallic cobalt core shelled by N-doped carbon (Co@NC) structure which operates as an oxygen evolution electrode. Specifically, a new cocrystal compound, [Co(μ-CN)(mmimp)] [CoClN(CN)]·3CHOH (Co, mmimp = 2-methoxy-6-((methylimino)-methyl)phenol), was isolated consisting of Brucite disks of cobalt where the usual bridging μ-OH is replaced by μ-CN produced by the in-situ decomposition of dicyanamide (N≡C-N-C≡N). The cobalt atoms are bonded through the nitrogen atom of the cyanide. Remarkably, time dependent thermogravimetric-mass spectrometry (TG-MS) analysis was utilized to track its pyrolysis process. It allowed us to propose a possible formation process of the Co@NC structure from Co. Interestingly, an extremely superior OER electrode is optimized for Co@NC-600 having the lowest overpotential of 257 mV at 10 mA/cm in 1 mol/L KOH solution. The present study pins down the importance of clusters of transition metals on realizing distinct nanostructures operating as highly efficient OER electrocatalyst.
在新型材料平台中，高效析氧反应（OER）催化剂的开发仍缺乏对前驱体可控热解机制的探索。在此，首次引入了一种新型钴基配位分子簇作为前驱体，以获得由氮掺杂碳包覆的金属钴（Co@NC）结构，该结构用作析氧电极。具体而言，分离出了一种新的共晶化合物[Co(μ-CN)(mmimp)][CoClN(CN)]·3CHOH（Co，mmimp = 2-甲氧基-6-((甲基亚氨基)-甲基)苯酚），它由钴的水镁石盘组成，其中通常的桥连μ-OH被由双氰胺（N≡C-N-C≡N）原位分解产生的μ-CN取代。钴原子通过氰化物的氮原子键合。值得注意的是，利用时间相关热重-质谱（TG-MS）分析来跟踪其热解过程。这使我们能够提出从Co形成Co@NC结构的可能过程。有趣的是，一种极其优异的OER电极针对Co@NC-600进行了优化，在1 mol/L KOH溶液中，在10 mA/cm²时具有257 mV的最低过电位。本研究确定了过渡金属簇对于实现作为高效OER电催化剂的独特纳米结构的重要性。
