Noble-metal-free Cu-Co/f-MWCNT electrocatalyst for methanol and ethanol oxidation reactions

In this study, the design and preparation of a nanohybrid electrocatalyst; Cu-Co/f-MWCNT was presented. The fabrication of present nanohybrid based electrocatalyst was carried out in two steps: firstly, the copper and cobalt nanoparticles were immobilized on/in functional multi-walled carbon nanotubes (f-MWCNT) by chemical deposition, then the Cu-Co/f-MWCNT nanohybrid was used to modified the carbon paste electrode (CPE). The Cu-Co/f-MWCNT/CPE was comprehensively investigated and confirmed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, transmission electron microscopy and electrochemical techniques. The obtained results indicate a uniform distribution of Cu-Co nanoparticles on/in the f-MWCNT structure and the formation of a nanohybrid structure with a high specific surface area and favorable electrical conductivity. The fabricated electrocatalyst; Cu-Co/f-MWCNT/CPE showed excellent electrocatalytic activity for the oxidation of methanol and ethanol in alkaline medium. Linear sweep voltammetry experiments have revealed wide linear ranges for the oxidation of methanol (0.5 to 3.0 M) and ethanol (1.0 to 3.5 M) in this condition. The outstanding performance of this system is due to the synergistic effect between Cu-Co nanoparticles in the nanohybrid structure and the high conductivity of f-MWCNT, which leads to fast electron transfer and an increase in the number of activated sites on the modified electrode surface. These results make Cu-Co/f-MWCNT/CPE a promising candidate for application in direct alcohol fuel cells.