Performance of platinum‐based spherical mercury microelectrodes in cyclic voltammetry and stripping analysis

Abstract

The performance of spherically shaped mercury microelectrodes. formed by electroreduction of mercury onto an inlaid platinum microdisk of radius Y , characterized by different deposit heights, 11, have been investigated for cyclic (CV) and anodic stripping (ASV) voltammetry.Electrodes with h / r ratio in the range 0.1-2 have been tested in solutions containing Pb" and CdZf in NaCl and NaC104 + HC104 as supporting electrolytes. For cyclic vodtammetry the results obtained indicated that the width at half height ( w , ,~) .the peak current (ip) and the charge of the anodic stripping peak (Q,) depend on the h / r parameter. Particular attention has been devoted to the relation between the charge of the cathodic process and thle anodic charge of the stripping peaks. It has been found that the experimental charge values involved in the cathodic and anodic scan agree within 3%, irrespective of the mercury thickness, indicating a complete stripping of the metals deposited in the mercury. For ASV the Pt-Cd intermetallic compounds have been found to influence the stripping peak of cadmium for electrodes with h / r < l and for concentrations of Cd" lower than 10-6M. By exploiting the known properties of the mercury microelectrodes in stripping analysiz,, an absolute method, based on the charge associated with the stripping peak, has been applied for determining the labile fraction of the above cations in a pore-water sample of the Venice lagoon.

Employment of Peak Area in the Determination of Metals Having Low Reversibility Degree of the Electrodic Process

“…Many authors use indifferently either the peak current or the peak area for measurements relevant to environmental problems [2], element speciation [3±5] or theoretical studies related to the employment of different electrodes [6,7]. In our previous communication [8] a critical comparison on the use of peak area and peak current emphasized that, in the case of reversible electrodic processes, the analytical metal determinations are equally possible employing both instrumental measurements with good precision and accuracy, and that the more evident advantage of using the peak area instead of the peak current is a lower limit of detection.…”

In Situ Scanning Electrochemical Microscopy (SECM) Detection of Metal Dissolution during Zinc Corrosion by Means of Mercury Sphere‐Cap Microelectrode Tips

“…Deposition of mercury onto the above-characterized platinum microdisks was carried out under potentiostatic control by setting the microelectrode potential at À0.10 V versus Ag/AgCl/KCl sat in Hg 2 A C H T U N G T R E N N U N G (NO 3 ) 2 (5 mm) + KNO 3 (0.1 m) acidified to pH 1 with HNO 3 . [37] The size of the mercury sphere caps thus produced was controlled by measuring the charge spent during the electrodeposition step from the corresponding chronoamperometric curve. The mercury microelectrode aspect ratio, described by the parameter H = h/a, that is, the ratio of the spherecap height (h) to the basal radius of the electrode (a) was obtained from the steady-state limiting current recorded in deaerated [RuA C H T U N G T R E N N U N G (NH 3 ) 6 Cl 3 ] (1 mm) + KCl (0.1 m) solution by using the method described in ref.…”

“…Mercury-coated metal microelectrodes [33] have been extensively used for anodic stripping voltammetry (ASV) of trace metal ions in aqueous solutions. [34][35][36][37][38][39][40] More recently, mercury microelectrodes have also been successfully employed as SECM tips to approach solid/solution interfaces to monitor various metal ions, including Zn 2 + , Cd 2 + , Pb 2 + , Cu 2 + , Mn 2 + , and Tl + . [41][42][43][44][45][46][47] Moreover, the functions to predict diffusioncontrolled steady-state currents [48] and approach curves at sphere-cap tips for both negative and positive feedback conditions are available.…”

Mercury Ion Monitoring in Mercury Plating Bath by Anodic Stripping Voltammetry

“…Platinum and glassy carbon are the main surfaces to make the thin Hg film since those do not easily form the alloy of mercury, amalgam [1][2][3][4]. The main application of the film is the determination of heavy metal ions in ppm or ppb level by anodic stripping voltammetry (ASV).…”