Mercury(II) immobilized on carbon nanotubes: Synthesis, characterization, and redox properties

Mercury(II)-modified carbon nanotubes can be readily prepared by reacting p urified/oxidized carbon nanotubes (CNTs) with a Hg(NO3)(2) aqueous solution . Two types of surface-confined Hg(II) species are formed and have been ide ntified as (CNT-COO)(2)Hg-II and (CNT-O)(2)Hg-II. These two complexes have a surface concentration ratio of about 30%:70%, on the basis of data obtain ed from high-resolution XPS spectra, Raman spectroscopy, and electrochemica l measurements. The electrochemical behavior of Hg(II)-modified CNTs adhere d to electrode surfaces in contact with CH3CN (electrolyte) strongly depend s on the nature of the working electrode used and the size of electrolyte c ation. Significant voltammetric changes also are observed after the additio n of water to the initially water-free acetonitrile electrolyte solution. A t a glassy carbon electrode and using NaClO4 as the electrolyte, a proposed mechanism is operative. However, at a gold-coated quartz-crystal electrode , Hg formed after reduction reacts with the Au to form Hg-Au alloy which ha s a very positive stripping peak potential value compared to that for the H g film formed on glassy carbon surfaces. The influence of the electrolyte c ation size on the reduction of Hg(II)-modified CNTs is attributed to the in tercalation of electrolyte cations.