Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel.
Chemphyschem. 2011 Mar 14;12(4):854-62. doi: 10.1002/cphc.201000653. Epub 2011 Jan 26.
Combined application of cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) technique reveals a complicated interplay between the adsorption of ammonium and lower molecular weight tetraalkyl ammonium cations and desorption of Cl(-) anions inside carbon micropores at low surface charge densities, which results in failure of their permselectivity. Higher negative surface charge densities induce complete exclusion (desorption) of the Cl(-) co-ions, which imparts purely permselective behavior on the carbon micropores. The second fundamental effect discovered herein relates to the dominant role of anion desorption (as compared to cation adsorption), that is, overwhelming failure of permselectivity extends to high negative charge densities of the electrode in the presence of bulky tetraalkyl ammonium cations, which tend to be confined in the micropores of the carbon. The results obtained are important for advancement of high power density carbon-based supercapacitors, nanofiltration technologies with porous carbon membranes, and studies of ionic transport across biological membranes.
循环伏安法（CV）和电化学石英晶体微天平（EQCM）技术的联合应用揭示了在低表面电荷密度下，铵和低分子量四烷基铵阳离子的吸附以及氯离子阴离子在碳微孔内的解吸之间的复杂相互作用，这导致了它们的选择性失效。更高的负表面电荷密度会导致氯离子共离子的完全排斥（解吸），从而赋予碳微孔纯粹的选择性行为。本文发现的第二个基本效应与阴离子解吸（与阳离子吸附相比）的主导作用有关，也就是说，在存在大体积四烷基铵阳离子的情况下，选择性失效会扩展到电极的高负电荷密度，而这些阳离子往往会被限制在碳的微孔内。所得结果对于推进高功率密度基于碳的超级电容器、具有多孔碳膜的纳滤技术以及研究离子跨生物膜的传输具有重要意义。
