In-situ synthesis of ZnO onto nanoporous gold microelectrode for the electrochemical sensing of arsenic(III) in near-neutral conditions

Abstract

The exploration of advanced electrochemical sensors towards highly toxic arsenic(III) has attracted growing interest in recent times. Herein, a ZnO decorated nanoporous Au (NPG) microelectrode was fabricated via a facile electrochemical alloying/dealloying method followed by thermal treatment, and developed for the electrochemical sensing of toxic As(III). Inspired by the electrochemical deposition of Zn and the formation of Au-Zn nanostructure on the surface of the Au microelectrode during the alloying/dealloying process, the in-situ evolution of the formed Au-Zn nanostructure to ZnO nanoparticles wrapped on the nanoporous Au surface was achieved. The ZnO/NPG microelectrode exhibited excellent electrochemical performance towards As(III) detection in near-neutral conditions (0.1 M phosphate buffer solution (PBS), pH: 5.0). A high sensitivity of 1.366 μA·ppb−1·cm−2 with a low limit of detection of 0.30 ppb (S/N = 3) was achieved at concentrations ranging from 1.0 ppb to 260 ppb. Moreover, the prepared ZnO/NPG microelectrode was successfully applied in the analysis of As(III) in tap and lake water samples with satisfactory recovery rates. The ZnO/NPG microelectrode presented exciting prospects for the electrochemical analysis of As(III) in near-neutral conditions.