Modified Thick-Film Graphite Electrodes: Morphology and Stripping Voltammetry

Abstract

This article reports on the results of the comparative analysis covering the interrelation between the surface morphology of thick-®lm graphite electrodes (TFGE's), which were modi®ed with mercury by reduction of mercury (II) ions from solutions (in situ) and solid compounds preliminary immobilized on the working surface of the electrodes (MTFGE's), and electrochemical and analytical characteristics of both analyte elements (Cu, Pb, Cd) and mercury. Conditions of the formation and destruction of ®lms of insoluble mercury compounds have been examined both during electrochemical regeneration of the electrode surface and during deposition of the mercury coating. The effect of these ®lms on electrochemical properties of MTFGE's has been discussed. Formation of an intermediate layer with anomalous electrochemical behavior was observed using only electrodes modi®ed with mercury in situ from the solution. Electrodes modi®ed preliminary with an insoluble mercury compound are free from this drawback. The methods of voltammetry and microscopy in situ (in real time) have been used.

Electrochemical Method for the Rapid on Site Screening of Cadmium and Lead in Soil and Water Samples

“…Quantifiable stripping peaks were obtained for all three analytes ( Figure 2). The broader and less well-defined Cu peak was considered due to the proximity of the Cu and Hg film oxidation potentials, irreversibility of the Cu 2+ reduction (Bradshaw & Scollary, 1997;Kadara et al, 2003) and the possible formation of insoluble Hg compounds, such as calomel, on the electrode surface due to the presence of Hg and chloride ions in the test solution (Jagner, Sahlin, & Renman, 1995;Nolan & Kounaves, 1999Zakharchuk, Saraeva, Borisova, & Brainina, 1999). This is reflected in the poorer correlation coefficient of 0.9970 achieved for Cu, as discussed below.…”

Mercury film electrodes: developments, trends and potentialities for electroanalysis

“…This latter method of plating compares favourably with in situ plating. 83 A method mainly used for silver substrates involves simple immersion of the electrode in liquid mercury to form the required mercury film; 84 this method can in principle be used with other amalgam-forming metal substates (e.g. Pt and Au).…”

Corrigendum: Realizing the Commercial Potential of Hierarchical Zeolites: New Opportunities in Catalytic Cracking

“…According to Zakharchuk et al. 26, under these conditions the Hg 0 nuclei remain immobile and do not coalesce into large droplets, remaining strongly bound to the surface structure. Additionally, the HCl solution is important to maintain constant the potential of the Ag pseudo reference.…”