Facile Synthesis of Core/Shell-like NiCo2O4-Decorated MWCNTs and its Excellent Electrocatalytic Activity for Methanol Oxidation.

Tae-Hoon Ko,Byoung-Suhk Kim,Hak-Yong Kim,Kesavan Devarayan,Min-Kang Seo

doi:10.1038/srep20313

Abstract

The design and development of an economic and highly active non-precious electrocatalyst for methanol electrooxidation is challenging due to expensiveness of the precursors as well as processes and non-ecofriendliness. In this study, a facile preparation of core-shell-like NiCo2O4 decorated MWCNTs based on a dry synthesis technique was proposed. The synthesized NiCo2O4/MWCNTs were characterized by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and selected area energy dispersive spectrum. The bimetal oxide nanoparticles with an average size of 6 ± 2 nm were homogeneously distributed onto the surface of the MWCNTs to form a core-shell-like nanostructure. The NiCo2O4/MWCNTs exhibited excellent electrocatalytic activity for the oxidation of methanol in an alkaline solution. The NiCo2O4/MWCNTs exhibited remarkably higher current density of 327 mA/cm2 and a lower onset potential of 0.128 V in 1.0 M KOH with as high as 5.0 M methanol. The impressive electrocatalytic activity of the NiCo2O4/MWCNTs is promising for development of direct methanol fuel cell based on non-Pt catalysts.

Highlights

The design and development of an economic and highly active non-precious electrocatalyst for methanol electrooxidation is challenging due to expensiveness of the precursors as well as processes and non-ecofriendliness
The morphologies of the synthesized NiCo2O4/multiwall carbon nanotubes (MWCNT) were investigated by using FE-scanning electron microscopy (SEM) and TEM measurements
We report a new and easy synthetic route to prepare core-shell-like NiCo2O4/MWNTs via a dry synthesis method

Summary

Activity for Methanol Oxidation

Tae-Hoon Ko1,*, Kesavan Devarayan2,4,*, Min-Kang Seo[3], Hak-Yong Kim1,2 & Byoung-Suhk Kim[1,2]. The impressive electrocatalytic activity of the NiCo2O4/ MWCNTs is promising for development of direct methanol fuel cell based on non-Pt catalysts. NiCo2O4 exhibits excellent electrochemical activity due to higher electronic conductivity than either NiO or Co3O49,10 Several synthetic strategies, such as conventional hydrothermal[11,12,13,14,15], solvothermal[16,17,18], electrochemical synthesis[19,20] were for the preparation of Ni and Co-based bimetal oxide electrocatalysts with different morphologies. To the best of our knowledge NiCo2O4/MWCNT has not been synthesized via such a simple grinding method followed by low temperature annealing Further this is the first study to demonstrate the use of NiCo2O4/MWCNT as an electrocatalyst for direct methanol fuel cell. The electrochemical impedance spectroscopy (EIS) was recorded in the frequency range of 10 mHz to 100 kHz with a potential amplitude of 10 mV

Results and Discussion

Present study

Conclusions

Additional Information