ILs-Based Multifunctional Compounds for Electrocatalysis and Biosensors

polyoxometalates (POMs), and even glucose oxidase (GOD) as the counter-anions (Fig. 4.14a, SWNT-IL-X) [56]. The properties of SWNT and the various anions were facilely and successfully delivered into the resulting compounds. For example, the rich redox activity was also successfully transferred into SWNT-IL-POM merely by a simple and facile anions exchange. The surface-confined SWNT-IL-POM shows three couples of well-defined redox waves at scan rates up to 2 V/s (Fig. 4.14b), which was presumably attributed from electron conduction of SWNT, ionic conduction of IL, and redox conduction of POM. It was unusuai for an often-seen compound in electrochemical systems. 

Moreover, due to the controllable wettability by counteranion exchange [56, 57], SWNT-IL-Br, which was both hydrophobic and hydrophilic, could assemble at the water/oil interface in a controllable manner, i.e., from monolayer to multilayers [58]. Thus, it enabled a novel SWNT-sandwiched water/oil interface for the electron transfer, one of the most fundamental chemical processes 

Results indicated that the ionic liquid-like unit on SWNTs, which did not depend on pH, would provide an extra and stronger ionic affinity between SWNTs and GOD so as to enhance the loading efficiency of GOD on SWNTs (Fig. 4.16). The direct electrochemistry of GOD was also achieved on PFIL wrapped polyvinylpyrrolidone (PVP)-graphene (Fig. 4.16a). Moreover, in these novel graphene-bionanocomposites, the specific substrate-enzyme bioactivity of GOD in the bionanocomposites was reserved, which could be utilized to build the electrochemical biosensor toward detection of glucose (Fig. 4.16b). 

Illustration of the preparation procedures of CNT-IL-Au Reprinted from Ref. [61], copyright 2008, with permission from Elsevier. 

Besides, ILs unit could be attached to the sidewall of CNTs by radical grafting, in which acid-oxidation pretreatment of CNTs could be avoided. Chen et al. reported that thermal-initiation free radical polymerization of the IL monomer 3-ethyl-l-vinylimidazolium tetrafluoroborate ([VEIM]BF4] on the CNT surface (Fig. 4.18a] [62]. Then under similar method, the Pt and PtRu nanoparticles with narrow size distribution (average diameter (1.3 0.4] nm for PtRu, (1.9 0.5] nm for Pt] are dispersed uniformly on the CNTs and show better performance in methanol electrooxidation than that without ILs units (Fig. 4.18b]. 

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