Nitrogen-Doped Graphene Aerogel Microspheres Used as Electrocatalyst Supports for Methanol Oxidation

Nitrogen-doped graphene aerogel microspheres (rGNAMs) are prepared by electrospraying the graphene oxide dispersion with pyrrole and an oxidation agent and then subjecting it to freeze-drying and thermal annealing. The rGNAMs possess a high surface area, an interconnected pore structure, and uniform N doping. The Pt nanoparticles (Pt NPs) are loaded into rGNAMs through a hydrothermal reduction reaction to obtain the Pt/rGNAM composite catalyst for methanol electrooxidation. The N-doping structure of rGNAMs can improve the loading ratio of Pt on the carrier, decrease the dimension of Pt NPs, homogenize the dispersion of Pt NPs, and increase the content of Pt(111) crystal planes. Consequently, the oxidation activity of Pt/rGNAMs to methanol is improved compared to that without N doping. The optimized Pt/rGNAM composites used as anode electrocatalysts display a remarkable mass activity of 840.11 mA mg–1 for methanol electrooxidation, which is about 4.9, 2.9, and 2.7 times higher than that of Pt/C, Pt/rGNAB (Pt/N-doped graphene aerogel bulk), and Pt/rGNAS (Pt/N-doped graphene aerogel millimeter spheres), respectively. Moreover, the Pt/rGNAMs also show superior long-term electrocatalytic stability. This work develops a new Pt/rGNAMs composite for potential application in fuel cells.