Enhanced Cathodic Preconcentration of As(0) at Au and Pt Electrodes for Anodic Stripping Voltammetry Analysis of As(III) and As(V)

Abstract

We report that the cathodic preconcentration of electron-insulating As(0) on Au and Pt electrodes can be enhanced by chemical reduction of As(III) and As(V) by electrogenerated H2, as studied by cyclic voltammetry. This finding is used for sensitive anodic stripping voltammetry (ASV) analysis of As(III) and/or As(V) at the Au electrode. About three As(0) monolayers were cathodically preconcentrated on the Pt electrode at −0.3 V (vs SCE) in 0.5 M aqueous H2SO4, as a result of both the chemical reduction of the solution-state As(III) near the electrode surface by the electrogenerated H2 and the direct electroreduction of As(III) on the highly catalytic surface Pt sites. Only one As(0) monolayer was electrodeposited at −0.2 V (vs SCE) on the Au electrode in 0.5 M aqueous H2SO4, but about two As(0) monolayers were deposited on the Au electrode at a more negative potential at which the mild evolution of H2 occurred. The electrogenerated H2 could also chemically reduce As(V), though the direct electroreduction ...