Few layers graphene-based electrocatalysts for ORR synthesized by electrochemical exfoliation methods

Abstract

Graphene-based materials were synthesized by electrochemical exfoliation method (cathodic method) starting from a graphite sheet. In the established methodology, an initial immersion in H2SO4 was applied, followed by cathodic expansion in potassium sulphate, where the effect of the applied voltage was studied. Finally, by ultrasound treatment, the exfoliation was achieved to produce a dispersion of few layer graphene material. Once the optimum procedure was established, Pt nanoparticles were incorporated using H2PtCl6.6H2O. This incorporation was studied at each stage of the graphene-based material synthesis to determine which was the most adequate to obtain the highest Pt dispersion and the best distribution of the Pt nanoparticles. In this sense, the incorporation of Pt in the graphene-based material colloidal dispersion by stirring for 3 h and sonication for 1 h, results in Pt nanoparticles with an average size of around 1 nm with an excellent distribution in the carbon material. The performance of this catalyst was compared with the commercial Pt/C electrocatalyst, showing a great oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) activity, exceeding it by far when comparing the mass-specific activity (A gPt−1) In addition, it presents excellent stability and selectivity toward the 4-electron pathway in ORR, which is the most energy-efficient, and using half of the platinum loading compared to the commercial material.