Facile synthesis of porous (Co, Mn)3O4 nanowires free-standing on a Ni foam and their catalytic performance for H2O2 electroreduction

Porous (Co, Mn)(3)O-4 nanowires freely standing on a Ni foam are synthesized via a template-free growth method, followed by a thermal treatment in air. The nanowires are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. Their catalytic performance in H2O2 electroreduction is evaluated by linear scan voltammetry and chronoamperometry. Results show that a thermal treatment leads to the conversion of solid nanowires of MnCO3 + CoCO3 to porous nanowires of (Co, Mn)(3)O-4 via decomposition and reconfiguration, which is identified to be the catalytic active component for H2O2 electroreduction. Nanowires calcined at 300 degrees C exhibit the highest activity for H2O2 reduction and a current density of 329 mA cm(-2) is obtained in 3.0 mol dm(-3) KOH + 0.6 mol dm(-3) H2O2 at -0.4 V (vs. Ag/AgCl, KCl). The catalytic activity of (Co, Mn)(3)O-4 nanowires is almost twice than that of Co3O4 nanowires. The role of Mn in improving the catalytic activity is proposed and discussed.