The influence of carbon spheres and graphene synthesized by thermal method as platinum-tin electrocatalyst supports to enhance the ethanol oxidation

Abstract

The direct ethanol fuel cell research for high efficiency and portable applications aims to enhance the electrochemical activity and lifetime of the electrocatalyst. Nonetheless, the major portion of electrocatalyst consists of support, 60 to 80% m/m. The physical–chemical properties of support material can directly influence electrochemical activity. This study compares different carbon allotropes as supports of Pt3Sn electrocatalyst, carbon black (C) and graphite (Gr) by commercial acquisition, and carbon spheres (CS) and graphene (G) prepared by our research group using hydrothermal synthesis and thermal expansion methods, respectively. Carbon black is the widely used support. Adopting it as a reference, in acid electrolyte, the forward oxidation current of CV decreases 97% (Pt3Sn/CS), 62% (Pt3Sn/G), and 78% (Pt3Sn/Gr). Nonetheless, in chronoamperometry (CA), Pt3Sn/G exhibited an increase of 48% in the final current compared with Pt3Sn/C, while Pt3Sn/CS current decreased 94% and Pt3Sn/Gr 67%. In alkaline electrolyte, Pt3Sn/G excels further among other materials once the ethanol oxidation current increases 60% in cyclic voltammetry (CV) and final current 36% higher by CA. The other allotropes decreased 99% (Pt3Sn/CS) and 54% (Pt3Sn/Gr) in cyclic voltammetry and exhibited a CA final current 84% (Pt3Sn/CS) and 12% (Pt3Sn/Gr) lower than Pt3Sn/C. Pt3Sn/G has high electrical conductivity and a large surface area which can contribute to enhancement of ethanol oxidation in activity sites. Therefore, the allotrope structure directly influences the electrochemical activity and that can be used to enhance the ethanol oxidation by electrocatalyst, where graphene supports the best improvement.