Catalytic one-step synthesis of Pt-decorated few-layer graphenes

Abstract

This study presents the influence of the various reaction parameters (catalyst concentration, reaction temperature, hydrocarbon flow rate, and reaction time) on the one-step growth of few-layer graphenes decorated with metallic platinum (Pt) nanoparticles. The latter were synthesized over a Pt/MgO catalyst using radio-frequency catalytic chemical vapor deposition (CCVD) from methane. A mixture of nanotubes and graphenes in various ratios was produced depending on the synthesis conditions. The nanotubes have a few walls (generally 2 or 3, but the maximum number observed was 7) with diameters in the range of a few to several nanometers (D^max_ext ≈ 7 nm). The graphene structures have a few square-shaped layers with dimensions ranging between 80 and 100 nm, which are decorated with Pt nanoparticles (with 70% having diameters between 4 and 8 nm) both on the flat surfaces as well as on the edges. Our experimental findings demonstrate that it is relatively easy to obtain predominantly graphenes using the Pt/MgO (2 wt% Pt) catalyst system at 1000 °C, with a 100 mL min⁻¹ hydrocarbon flow rate and a reaction time of 30 minutes.