Structure-switching of an organothiol neutral carrier by gold nanoparticles decorated on SH-MWCNTs for ultra-trace voltammetric assay of Hg(ii) using a carbon paste electrode

Abstract

A simple strategy has been developed based on 1,2-bis[5,2-thiolmethyl-sulphide-1,3,4-oxadiazol-2-yl]ethane (BTMSOE) as a novel ion-carrier for construction of a voltammetric Hg(II)-CPE. AuNPs not only have strong inter-particle binding affinity (Au-Au), but also have strong tendency to form S-Au covalent bonds with -SH functional groups. In view of this fact, by self-assembling of AuNPs, the spatial configuration of the thiol-terminated BTMSOE compound was switched from podant to macrocycletype ligand. The macrocycle-type BTMSOE-AuNP compound was then immobilized by self-assembly on the super-conductive MWCNT substrate via a (3-mercaptopropyl) trimethoxysilane (MPTS) covalent linker. Under the optimized conditions, the oxidative current I p,a (mA) exhibited a linear dependence on Hg(II) ion concentration in the wide dynamic concentration ranges of 3.5 Â 10 À11 to 3.7 Â 10 À7 M and 1.2 Â 10 À6 to 1.0 Â 10 À4 M (R 2 ¼ 0.9947 and 0.9992, respectively). Moreover, the limit of detection of the proposed sensor was 1.7 Â 10 À12 mol L À1 (S/N ¼ 3) at a working optimal pH of 4.2 adjusted by ABS as an appropriate supporting electrolyte. These features, specifically the high sensitivity and exceptional selectivity, were positively compared with those of previously reported methods in the area of electrochemical Hg(II) detection. Eventually, the practical utility of the prepared MWCNTs/AuNPs/ BTMSOE-CPE was assessed for efficient determination of Hg(II) contents in aqueous environmental samples with different matrices such as tap and mineral water, tuna fish, human hair, and tobacco.

Electrochemical Reaction Assisted 2D π-Stacking of Benzene on a MWCNT Surface and its Unique Redox and Electrocatalytic Properties

“…A carbon nanotube (CNT) is one of the revolutionary discoveries in the 20th century. , The exceptional carbon molecular network structure and physical properties like high conductivity, high surface area, and mechanical strength of CNTs have been attracting scientists of different disciplines and researchers to utilize this material for extending its application fields. , Functionalization of CNT is a cutting-edge research topic in the material application field. In general, following methodologies are adopted for functionalization of CNTs: (i) covalent modification, , (ii) self-assembling, (iii) π–π bonding, (iv) encapsulation, , (v) chemical and electrochemical polymerization of organic monomers, , and (vi) nanocomposites. , In all of these modifications, a few monolayer thick target molecules have been adsorbed on the CNT surface. Herein, we first report a specific functionalization of multiwalled carbon nanotube (MWCNT) as benzene moiety π-stacks, designated as MWCNT@[BZ]-π-stack, prepared by the surface-confined electrochemical reaction of the benzene–water cluster ({BZ-H 2 O}) at 1.2 V vs Ag/AgCl in mild acidic conditions (pH 2 KCl–HCl), wherein the diameter of the CNT is increased over 10-fold.…”

“…3,4 Functionalization of CNT is a cuttingedge research topic in the material application field. In general, following methodologies are adopted for functionalization of CNTs: 5 (i) covalent modification, 6,7 (ii) self-assembling, 8 (iii) π−π bonding, 9 (iv) encapsulation, 10,11 (v) chemical and electrochemical polymerization of organic monomers, 12,13 and (vi) nanocomposites. 14,15 In all of these modifications, a few monolayer thick target molecules have been adsorbed on the CNT surface.…”