Boosting oxygen electrode kinetics by addition of cost-effective transition metals (Ni, Fe, Cu) to platinum on graphene nanoplatelets

Pt and Pt-M (M = Ni, Fe, Cu) nanoparticles supported on graphene nanoplatelets (GNPs) were synthesized by simultaneous supercritical carbon dioxide deposition method. Morphology analysis by TEM revealed the formation of metal nanoparticles of 2-3 nm size uniformly distributed over GNPs, while XPS was used to determine their oxidation states. Four materials were tested as electrocatalysts for ORR and OER in unitized regenerative fuel cells and rechargeable metal-air batteries. PtFe/GNPs exhibited favorable ORR kinetics in terms of the highest diffusion-limited current density, the lowest Tafel slope, and a high number of ex-changed electrons (n = 3.66), which might be attributed to its high double-layer capacitance and, thus, high electrochemically active surface area. Furthermore, this material performance was comparable to that of commercial Pt/C electrocatalyst containing double the amount of Pt. The same material showed the best performance toward OER as evidenced by the highest current density, the lowest value of exchange current density, and overpotential to reach a current density of 10 mA cm(-2), as well as the lowest Tafel slope. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, Pt and Pt-M (M = Ni, Fe, Cu) nanoparticles supported on graphene nanoplatelets (GNPs) were synthesized by simultaneous supercritical carbon dioxide deposition method. The morphology analysis revealed the formation of uniformly distributed metal nanoparticles on GNPs, and the XPS analysis determined their oxidation states. PtFe/GNPs exhibited favorable kinetics in both ORR and OER, and its performance was comparable to or even better than that of commercial Pt/C electrocatalyst.