Determination of sulfide by cathodic stripping voltammetry of silver sulfide films at a rotating silver disk electrode

Abstract

The deposltlon and stripping behavlor of sllver sulflde films at the silver rotatlng dlsk electrode were Investigated. The effect of various factors-rotatlon rate, scan rate, deposltlon potential and time, and concentration of sulflde Ion-on the stripplng peak current and potential were studled. The electrode has been found to be an excellent electrode for cathodlc strlpplng voltammetry for the determlnatlon of submicro amounts of sulfide Ion. Furthermore, dlfferentlal pulse voltammetry significantly enhanced the slgnal/nolse ratlo, and a linear response was obtalned over the concentration range 10-8-10-5 mol dm-' of sulfide Ion in 0.2 mol dm-3 NaOH.We describe a procedure for trace determination of sulfide ion in solution based upon the cathodic stripping of electrodeposited Ag& This procedure evolved from studies of the formation of silver sulfide upon anodization of a silver electrode in sulfide-containing solutions and properties of the electrodeposited silver sulfide films at silver rotating disk electrodes (RDE) (1, 2).Although anodic stripping voltammetry (ASV) is a wellestablished technique for the determination of trace levels of metal ions in solution, the equivalent method for the determination of anions by cathodic stripping voltammetry (CSV) is less established. Most of the reported applications of CSV for anions which form sparingly soluble compounds with the electrode have been carried out at hanging mercury drop or mercury pool electrodes. The determination of trace quantities of halide ( 3 4 , sulfide (6-11), cyanide (12), cyanoferrate(I1) and -(III) (13) and selenide ions (14,15), and various thiols (16-21) by deposition of their insoluble mercury salts has been reported. Several extensive reviews (22-24) covering stripping analysis have appeared and the reviews by Brainina have extensive sections on CSV.Trace amounts of iodide were determined by CSV by Shah and Perone (25) as early as 1961. Although they used a silver electrode, it appears that little work with this electrode for CSV has been performed since.The solution containing the analyte is usually vigorously stirred during deposition (ASV) or film formation (CSV) to increase the efficiency of the deposition step. The stripping (ASV) step is usually carried out from a quiescent solution since stirring perturbs the mercury drop or pool electrode (26). Since the rotating electrode hydrodynamics are very well defined, increasing use has been made of thin-film mercury electrodes on rotating glassy carbon substrates. However, there is a significant lack of literature on the use of an RDE for anion determinations employing CSV.This paper reports on the deposition and stripping of silver sulfide films at a silver RDE and describes a procedure for the determination of submicro levels of sulfide. Linear potential scan or differential pulse voltammetry is employed during the reduction step stripping the Ag2S from the electrode surface.EXPERIMENTAL SECTION Reagents. Analytical grade sodium sulfide (Na2S-9H20, Mallinckrodt Inc.) and sodium hydroxide ...

CdS and ZnS Deposition on Ag(111) by Electrochemical Atomic Layer Epitaxy

“…5c coincide with the experimental as well as the calculated potential shifts of Ref. 23. This proves that the sulfur layers remaining after the anodic stripping of cadmium or zinc behave like bulk sulfur.…”

“…23. The cathodic stripping process of the sulfur deposited either on a stationary or on a rotating silver electrode was found not to be controlled by the diffusion of sulfide ions from the electrode surface but by other kinetics.…”

Ternary cadmium and zinc sulfides and selenides: electrodeposition by ECALE and electrochemical characterization

“…Another indication for the contemporary release of both cations is given by the successive cathodic stripping of S. In fact, once all of the metallic element has been stripped anodically, the remaining sulfur layers, except for the first, are reduced at more positive potentials than the first sulfur layer in contact with the silver substrate. The comparison with the cathodic stripping voltammetry of silver sulfide films described in [24] proves that the sulfur layers remaining after the anodic stripping of the cations behave like bulk sulfur. If part of the cations was not re-dissolved, or one of the two corresponding binary compounds still remained on the electrode, then the cathodic stripping curves should be shifted towards more negative potentials in a way symmetrical to the positive shift observed for the stripping curves of the cations.…”

Interactions of methylated adenine derivatives with the mercury electrode

“…1.1.3.9) is extremely interesting because many of its substrates are of analytical import. These include galactose, lactose, glycerin, dihydroxyacetone, and glyceraldehyde (1 7, 18). We have previously demonstrated how galactose oxidase can be reversibly turned on and off by oxidizing and reducing it, respectively, using a thin-layer electrochemical cell and a mediator titrant (19).…”