Non-precious Sn as alternative substitute metal in graphene-based catalysts for methanol electrooxidation

Monometallic and bimetallic Pt-based electrocatalysts were synthesized via a wet impregnation method using graphene (Gr) as the support and characterized by spectroscopic, imaging, and electrochemical means. The performance of a Pt/Gr catalyst was compared with that of PtRu/Gr and PtSn/Gr catalysts for the electrocatalytic oxidation of methanol. Although Pt monometallic catalysts exhibit sufficient electrocatalytic activity during methanol oxidation, degradation problems associated with surface poisoning processes by reaction side products limit their perspective for commercial use. Alloying Pt with other metals appears to be an effective method for producing highly active electrocatalysts for the same reaction. Physicochemical characterization reveals the incorporation of Sn atoms into the Pt lattice. We provide an in-depth investigation of graphene-based catalysts during the oxidation reaction of methanol, which is a promising fuel for direct alcohol fuel cells. In conjunction with the literature, our results demonstrate that the interaction between metal particles and carbon support is of paramount importance for electrode stability and catalytic performance. Critically, the electrocatalytic activity dependeds on the details of the electrode surface structure and electronic interaction - charge transfer between metal nanoparticles and graphene. It is also proposed that high specific surface area graphene support can facilitate methanol diffusion to the catalyst active sites leading to high electrochemical activity. This work also demonstrates that a low-cost metal, like Sn, can effectively replace Ru to prepare bimetallic Pt-based electrocatalysts for methanol oxidation. The electrocatalytic activity of the Pt-Sn catalyst was found to be similar to that of the Pt-Ru one.

Automated summary

Pt-based electrocatalysts, both monometallic and bimetallic, synthesized using graphene as the support, showed improved performance for the electrocatalytic oxidation of methanol. The interaction between metal particles and carbon support, as well as the surface structure and electronic interaction, played crucial roles in the electrocatalytic activity.