Abstract
In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.
Highlights
Direct methanol fuel cells (DMFCs) are very promising clean power sources for portable applications owing to their relatively high energy density, low operating temperatures and ease of handling of liquid fuel[15,16]
The results indicate that the Pt/S-Reduced graphene oxide (rGO) possesses a much higher electrocatalytic activity and better stability towards MOR of DMFCs, as compared with Pt on high surface area Vulcan carbon and on rGO (Pt/VC and Pt/rGO) electrocatalysts
The S-rGO aqueous suspension at a concentration around 0.01 mg mL−1 under neutral conditions has a zeta potential of − 62.4 mV, which is much lower than − 10.4 mV observed on rGO, indicating the success of the fuctionalization by taurine and the very good stability of the suspension[12,41]
Summary
Direct methanol fuel cells (DMFCs) are very promising clean power sources for portable applications owing to their relatively high energy density, low operating temperatures and ease of handling of liquid fuel[15,16]. Chung et al.[27] prepared Pt/graphene using a pulsed galvanostatic electrodeposition method and showed the improved electrocatalytic activity for MOR as compared with a commercial Pt/C catalyst, which was attributed to the synergistic effects between the Pt NPs and graphene sheets. The excellent electrocatalytic activity was ascribed to the porous honeycomb-like surface structure, large surface area and enhanced interactions between graphene and Pt NPs. Pt/graphene electrocatalysts were synthesized through a chemical reduction route using ethylene glycol as reducing agent and showed a high electrocatalytic activity for MOR29. We developed a facile method to synthesize sulfonic acid-grafted graphene oxide, S-rGO, as effective catalyst supports to prepare Pt/S-rGO electrocatalysts via a self-assembly route. The results indicate that the Pt/S-rGO possesses a much higher electrocatalytic activity and better stability towards MOR of DMFCs, as compared with Pt on high surface area Vulcan carbon and on rGO (Pt/VC and Pt/rGO) electrocatalysts
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