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

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 CO2 and the evidence supports the Eley-Rideal mechanism of CO oxidation, where the presence of oxygen does not affect the oxidation process.