Facile synthesis of Co/rGO, Au/rGO, and CoAu/rGO nanocomposites for precise determination of Arsenic(III) in water systems

Abstract

Cobalt (Co), gold (Au), and cobalt-gold (CoAu) nanoparticles were deposited on reduced graphene oxide (rGO) by a facile and scalable procedure. The synthesised nanocomposites (Co/rGO, Au/rGO, and CoAu/rGO) were used as electrode materials for detecting trace amounts of arsenic (As(III)) ions in water samples. All three electrodes responded to the presence of As(III) in an acidic medium (different acids of the same concentration, then chosen acid at different concentrations). A detailed optimization of the conditions was continued with the CoAu/rGO electrode which showed the best response in terms of the best defined peak indicating the oxidation of As(0) to As(III) and the highest current. The electrode was tested in a wide range of concentrations (30–1000 µM), where two areas of linearity and limits of detection were obtained (for low- and high- concentrations). Moreover, this electrode showed the ability to detect As(III) ions in the presence of Cu(II), as an interference model as well as a satisfactory electrochemical response, in terms of a clear peak corresponding to the oxidation of As(0) to As(III) in a real sample.