Comparison of methanol oxidation reaction process for NiCo2O4/X (X = rGO, MWCNTs, HCNs) nanocatalyst

Abstract

Carbonaceous materials are well known for their extraordinary properties, such as availability, cheapness, and fantastic physical and electrochemical properties. Also, large surface area and high electrical conductivity make them the most proper candidates to use in the structure of catalysts. In this research, a binary transition metal oxide consisting of nickel and cobalt oxides in the form of NiCo 2 O 4 was synthesized by hydrothermal method, and then was hybridized with various carbon materials such as reduced graphene oxides (rGO), multiwalled carbon nanotubes, and hallow carbons to be used as catalyst for methanol oxidation. The physical structure of as-prepared catalysts was surveyed by XRD, SEM, and TEM analysis. Furthermore, the electrochemical capability of these catalysts was evaluated by methanol oxidation in an alkaline medium. The results showed that the hybrid of NiCo 2 O 4 with HCNs, MWCNTs, and rGO revealed oxidation peaks at 0.58, 0.57, and 0.58 V with the current density of 31, 37, and 63 mA/cm 2 at a scan rate of 20 mV/s in the optimal concentration of methanol. Besides, the stability of the catalysts after 100 consecutive CV cycles obtained 96 %, 97 %, and 99 %, respectively. Although the difference in the obtained values is low, the NiCo 2 O 4 /rGO showed the best performance in MOR. • NiCo 2 O 4 /X (X = rGO, MWCNTs, HCNs) were synthesized by hydrothermal method. • The ability of nanocatalysts in the MOR process was investigated. • NiCo2O4/rGO had more current density and cyclic stability than other catalysts.