Electrocatalytic reduction of chloroform at nanostructured silver electrodes

Abstract

In this work we report the comparison of the electrocatalytic properties of silver nanowire (NW) array, nanohemisphere (NHS) array, and silver rod (Ag-bulk) electrodes in an alkaline solution. The silver nanohemisphere (Ag-NHS) and nanowire (Ag-NW) array electrodes were fabricated by electrodeposition into nanoporous aluminum oxide (AAO) templates. The silver nanohemisphere array electrodes were synthesized by metal sputtering on the Al2O3/Al substrate having hemispherical nanopores followed by electrodeposition of Ag. To fabricate the AAO with hemispherical pores on Al substrate, repeated cycles of alternating anodization and pore widening treatment were performed. On the other hand, the silver nanowires electrodes were prepared by electrodeposition of Ag into the nanoporous AAO template. The electrocatalytic properties of synthesized nanostructured Ag electrodes toward electroreduction of chloroform were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). All experiments were carried out in an Ar-saturated 0.1M NaOH solution. A long-term response of Ag-NW and Ag-NHS electrodes to CHCl3 was investigated after 14 and 28days of storage in air. It was found that the storage time does not significantly affect the electrocatalytic performance of electrodes. To investigate the possible changes in the chemical composition and surface morphology of Ag NW array electrode caused by electrocatalytic reduction of chloroform during CV cycling, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used.