Superior anti-poisoning performance of graphenes versus carbon nanotubes as Pt catalysts supports for formate oxidation

Pt nanoparticles were prepared and deposited on carbon nanotubes (CNTs) and graphene nano-sheets (GNs) to obtain composites of Pt/CNTs and Pt/GNs, respectively. The morphologies of Pt particles for the two catalysts were observed using transmission electron microscopy (TEM). It showed that the average Pt sizes for Pt/CNTs and Pt/GNs are similar, meaning that the differences in the electrochemical performance of the two catalysts could be ascribed to support effects. Pt/CNTs and Pt/GNs were quantitatively compared by simultaneously analyzing their cyclic voltammetry (CV) and chronoamperometry (CA) data for formate oxidation, showing that Pt/GNs is evidently superior to Pt/CNTs in terms of anti-poisoning performance. CO stripping on the two catalysts indicated that the strength of CO adsorption on GNs-supported Pt is weaker than that for CNTs-supported Pt. The X-ray photoelectron spectroscopy (XPS) spectra showed that the binding energy of Pt 4f for Pt/GNs was higher than that for Pt/CNTs, indicating a stronger interaction of Pt with GNs than with CNTs and consequently a weaker adsorption of CO on GNs-supported Pt. We believe that this study can be used as a guide for future evaluation and screening of supports and/or anode catalysts for direct liquid fuel cells.