Free-standing Ni-Co alloy nanowire arrays: Efficient and robust catalysts toward urea electro-oxidation

Free-standing Ni-Co alloy nanowire arrays are synthesized via a modified template-assisted electrode-position method. The structure and composition analysis have been performed by employing X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The highly ordered nanowire arrays show a strong adherence to an alloy transition layer. Herein, the alloy nanowire arrays show higher electrocatalytic activity in terms of lower onset potential and higher peak current density compared to the sample synthesized by conventional deposition route for urea electro-oxidation. Moreover, the electrocatalytic activity can be facilely optimized by selecting the length of nanowire arrays (or the deposition time). The best sample deposited with a time of 600 s possesses an onset oxidation potential of 0.372 V (vs. Hg/HgO) and a peak current density of 322.82 mAcm(-2) in 1 M KOH and 0.33 M urea solutions. The sample also shows good stability and activity even after sonication treatment. The excellent electrocatalytic properties of urea oxidation are considered due to the one-dimensional free-standing nanoscale alloy structure, which can largely boost the active sites, facilitate charge transfer, and improve the duration of urea electro-oxidation. (C) 2018 Elsevier Ltd. All rights reserved.