Methanol Electro-oxidation by Carbon Supported Cobalt and Nickel based Nanocomposites

摘要

Activated carbon supported Co and Ni based nanomaterials were prepared using NaBH4 as a reducing agent and examined with respect to electrocatalytic methanol oxidation. The surface morphology and composition of the synthesised materials were examined using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy- dispersive X-ray spectrometry (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) was employed to confirm the typical metallic electrochemical response of the carbon supported Co, Ni and Co1Ni1 based materials. The metal hydroxides/oxides species were found to be dominant and their combination with nanoparticles in the activated carbon support resulted in an excellent response towards methanol electro-oxidation. The nickel based catalysts (Ni/C and Co1Ni1/C) showed much better response compared to Co/C, but the presence of Co provides low onset potential, stability and cost effectiveness and is capable of providing anti-poisoning strength. The current response per mg of Ni for Co1Ni1/C (I_(0.65)= 3.9 A/mg Ni) catalyst is higher (1.44 times) than Ni/C (2.7 A/mg Ni), and signifies the importance of effective utilisation of surface composition along with the modification in surface structure due to the inclusion of Co in Co1Ni1/C. The Ni content was reduced to half (Co1Ni1/C) without compromising catalytic activity and the synthesised materials have the potential to act as electrocatalysts for methanol oxidation. These materials may also be a very good alternative in a binary/ternary composition with Pt in order to reduce precious platinum content, to provide stability and anti-poisoning ability all of which are highly desirable features.