Enhanced electrocatalytic performance of cobalt oxide nanocubes incorporating reduced graphene oxide as a modified platinum electrode for methanol oxidation

Abstract

Cobalt oxide nanocubes incorporated reduced graphene oxide prepared by hydrothermal method and used for the electrocatalytic oxidation of methanol. AbstractHerein, we report a facile hydrothermal method for the preparation of cobalt oxide nanocubes incorporated reduced graphene oxide (rGO-Co 3 O 4 nanocubes) for electrocatalytic oxidation of methanol. The synthesized rGO-Co 3 O 4 nanocubes were characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Raman techniques. The electrochemical behavior of rGO-Co 3 O 4 nanocubes modified electrode was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The electrocatalytic performances of rGO-Co 3 O 4 nanocube-modified electrodes with different wt. % of GO were investigated in relation to methanol oxidation in an alkaline medium. The rGO-Co 3 O 4 nanocubes modified electrode showed enhanced current density due to oxidation of methanol when compared to the bare Pt, rGO, and Co 3 O 4 nanocubes modified electrodes. The optimal GO content for an rGO-Co 3 O 4 nanocube-modified electrode to achieve a high electrocatalytic oxidation of methanol was 2 wt. %, and it showed an anodic peak current density of 362 µA/cm 2 . IntroductionThe constantly increasing energy demand due to the depletion of conventional fossil fuel reserves and the rapid growth of environmental issues have led to search for alternative power sources. 1,2 These include direct methanol fuel cells (DMFCs) as alternative green, environmentally friendly, and sustainable power sources that can directly convert the chemical energy of methanol into electrical energy. 3,4 A polycrystalline Pt electrode is the most commonly used electrode material in DMFCs. However, its high cost, rarity, low power density, and poor CO-poisoning tolerance significantly hinder their commercialization and practical application. 5,6 In order to reach a high power density and low production cost for DMFCs, well-designed and fabricated high-performance electrocatalysts with controlled compositions and morphologies have been emerged as a key point for realizing high device performance. 5,6 In this area, carbon-based nanomaterials, including activated carbon, carbon nanotubes (SWCNT, DWCNT, MWCNT), GO, and rGO have enormous potential to boost the performance of DMFCs. 3,7,8 Among these, graphene plays a crucial role in the fabrication of advanced composite/hybrid electrocatalysts for high performance DMFCs because of its unique physicochemical properties, including a high specific surface area, superior electronic conductivity, and excellent stability. 8-13 Several attempts have been made to apply metal and metal oxide nanomaterials incorporated graphene modified electrodes in DMFC applications to attain a high power density. 14,15 Metal oxide incorporated graphene composite gained tremendous attention because of their low-cost, facile synthesis, high electrocatalytic activity, and durability in DMFC application...

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