单层石墨烯电解质界面的电化学表征

法国图卢兹第三大学Patrice Simon研究小组取得一项新突破。他们研究了单层石墨烯/电解液界面的电化学表征——溶剂对界面电容的影响。 该研究于2021年2月8日发表于《德国应用化学》。

在这项工作中，课题组人员以单层石墨烯(SLG)电极为模型材料，在规整(EMIm‐TFSI)和溶剂化(乙腈)离子液体电极上研究了双层电容的电荷。电化学阻抗谱和重量电化学石英晶体微天平(EQCM)的测量结果表明，溶剂的存在大大增加了SLG /离子液体界面的载流子密度。

电容不仅取决于石墨烯的电子性质，还取决于电解液表面的特定组织结构，这是由于EMIm +阳离子与电解液表面之间存在的强相互作用造成的。EQCM测量还表明，sp2碳的存在有利于SLG电极上的反离子吸附，而非无定型孔隙碳上的离子交换机制，从而影响了电荷存储机制。

研究人员介绍，对于用于储能应用的电极中电荷存储机制的基本理解的发展，需要对电极/电解质界面进行深入表征。

附：英文原文

Title: Electrochemical characterization of single layer graphene / electrolyte interface: effect of solvent on the interfacial capacitance

Author: Yih-Chyng Wu, Jianglin Ye, Gengping Jiang, Kun Ni, Na Shu, Pierre-Louis Taberna, Yanwu Zhu, Patrice Simon

Issue&Volume: 2021-02-08

Abstract: The development of the basic understanding of the charge storage mechanisms in electrodes for energy storage applications needs deep characterization of the electrode / electrolyte interface. In this work, we studied the charge of the double layer capacitance at single layer graphene (SLG) electrode used as a model material, in neat (EMIm‐TFSI) and solvated (with acetonitrile) ionic liquid electrodes. The combination of electrochemical impedance spectroscopy and gravimetric electrochemical quartz crystal microbalance (EQCM) measurements evidence that the presence of solvent drastically increases the charge carrier density at the SLG / ionic liquid interface. The capacitance is thus governed not only by the electronic properties of the graphene, but also by the specific organization of the electrolyte side at the SLG surface originating from the strong interactions existing between the EMIm  +  cations and SLG surface. EQCM measurements also show that the carbon structure, with the presence of sp2 carbons, affects the charge storage mechanism by favoring counter‐ion adsorption on SLG electrode versus ion exchange mechanism in amorphous porous carbons.

DOI: 10.1002/anie.202017057

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202017057