Facile synthesis of porous (Co, Mn)3O4nanowires free-standing on a Ni foam and their catalytic performance for H2O2 electroreduction

Abstract

Porous (Co, Mn)₃O₄ 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)₃O₄via decomposition and reconfiguration, which is identified to be the catalytic active component for H₂O₂ electroreduction. Nanowires calcined at 300 °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)₃O₄ nanowires is almost twice than that of Co₃O₄ nanowires. The role of Mn in improving the catalytic activity is proposed and discussed.