Cyanide ion-selective electrodes based on thin electroplated membranes of silver chalcogenides: Part I. Membrane preparation and characterization

Abstract

Cyanide-responsive ion-selective electrodes have been developed based on thin tellurium-doped silver selenide membranes electrodeposited on platinum substrates. The chemical composition of the electroplated film membranes could be expressed by the general formula Ag 2+δSe 1− x Te x (where 0.2 < δ < 0.8 and 0.2 ⩾ × ⩾ 0.1). These electrodes exhibit a linear response in cyanide solutions with concentrations ranging from 10 −2 to 10 −6 M, with a slope of the electrode function of about 90 mV (pCN) −1 (i.e., lower than the theoretically predicted double-Nernstian slope). These electrodes showed very stable behaviour during long-term investigation (several months). The conditions for the electrochemical preparation of cyanide-responsive silver chalcogenide membranes are discussed both from theoretical and practical points of view. X-ray diffraction, energy-dispersive x-ray fluorescence microanalysis (EDAX) and scanning electron microscopy (SEM) were used to examine the membrane composition, structure and surface morphology.