Precious metal free Ni/Cu/Mo trimetallic nanocomposite supported on multi-walled carbon nanotubes as highly efficient and durable anode-catalyst for alkaline direct methanol fuel cells

Abstract

Direct methanol fuel cells (DMFCs) proved to be an auspicious choice in the applications of portable power electronics and energy transportation, apart from their high cost catalysts materials. To this end, we have developed precious metal free low-cost active anode materials for DMFCs. Three metals composite (Ni, Cu, and Mo) based electrocatalyst on a multi-walled carbon nanotubes (MWCNTs) support were prepared. The sequential wetness impregnation at different temperatures method combined with a freeze-drying procedure was used to dope the metals nanoparticles on the carbon nanotube. Their compositions and textures were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) detector, elemental mapping, transmission electron microscopy (TEM), high resolution TEM and inductively coupled plasma-mass spectroscopy (ICP-MS). The electrochemical behavior of the prepared electrocatalysts for methanol oxidation was investigated in alkaline media. Cyclic voltammetry (CV) measurements indicate that the catalyst containing 80% of Ni, 10% of Cu and 10% of Mo shows a better electrocatalytic activity than those of other composites in present work. Also the incorporated co-catalysts (Mo and Cu) contribute significantly to the electrocatalytic activity along with Ni via NiCu and NiMo interfaces. The effect of scan rate and methanol concentration was also studied to evaluate the adsorption and oxidation of methanol molecules on the surface of catalyst. The chronoamperometry (CA) was used to evaluate the stability and durability of the as-synthesized Ni/Cu/Mo@MWCNTs catalyst.