Low Density Three-Dimensional Metal Foams as Significant Electrocatalysts toward Methanol Oxidation Reaction

Abstract

Transition metals have emerged as highly active catalysts for methanol oxidation reaction. The development of low-density metallic foams is exceedingly intriguing for various applications. Here, we report a systematic design of three-dimensional (3D) porous nanocomposites (foam) of transition metals like Cu and Ni with reduced graphite oxide (Cu–Ni@rGO) using simple self-propagation combustion method, where Cu–Ni foam structures are wrapped around reduced graphite oxide. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) show nanoporous structural morphology. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) show presence of different oxidation states of metal ions and phase formation, respectively. The electrochemical studies of Cu–Ni@rGO nanocomposites exhibit interesting methanol electrooxidation properties with exciting current density of 280 mA/cm 2, which further retain 95% of their activity even after 600 s. In addition, these, Cu–Ni@rGO structures also reveal negligible poisoning effects during methanol electrooxidation. More interestingly, Cu–Ni@rGO nanocomposites show remarkable electrochemical CO oxidation to form CO 2 and the evidence supports the Eley–Rideal mechanism of CO oxidation, where the presence of oxygen does not affect the oxidation process.