Synergistic enhancement of the electro-oxidation of methanol at tailor-designed nanoparticle-based CoOx/MnOx/Pt ternary catalysts

The current study addresses the enhanced electroctrocatalytic activity of a nanoparticle-based ternary catalyst composed of Pt (nano-Pt), manganese oxide (nano-MnOx), and cobalt oxide (nano-CoOx) (all were assembled on a glassy carbon (GC) substrate) towards the direct methanol electro-oxidation reaction (MOR) in an alkaline medium. The electrocatalytic activity of the modified electrodes towards MOR depends on the loading level of nano-Pt, nano-MnOx, and nano-CoOx onto the GC electrode as well as the order of deposition of each component. Interestingly, the CoOx/MnOx/Pt/GC electrode (with nano-Pt firstly deposited onto the GC surface followed by nano-MnOx then nano-CoOx) shows the highest catalytic activity and stability towards MOR for a prolonged time of continuous electrolysis. This is revealed from the large increase (seven times) in the peak current of MOR at this electrode compared with that obtained at Pt/GC electrode. The influence of operating pH on the catalytic activity of the proposed catalyst is investigated. Several techniques including cyclic voltammetry, field-emission scanning electron microscopy and energy dispersive X-ray spectroscopy and X-ray diffraction are used to address the catalytic activity of the catalyst and to reveal its surface morphology and composition.