Controlled growth cerium oxide nanoparticles on reduced graphene oxide for oxygen catalytic reduction

In this paper, a facile and simple strategy was developed for in-situ growth cerium oxide nanoparticles on reduced graphene oxide (rGO) through thermal treatment of the Ce³⁺-doped graphene oxide(GO) under nitrogen atmosphere. Through regulation the thermal treatment temperature, the growth of cerium oxide nanocrystals can be easily controlled in accompany with the reduction of GO. The morphology and chemical composition of the as-synthesized CeO₂/rGO at different temperature are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The nanocomposites show electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline solution. Especially, the cerium oxide nanoparticles/rGO nanocomposites treated at 750 °C possess excellent electrocatalytic ability with a dominating four-electron pathway, high tolerance of methanol and long-term operation stability due to the well exfoliation of graphene and perfect crystalline structure of cerium oxide. Compared to the commercial Pt/C catalyst, the synergistic effect of the fast electron transport of rGO and the high electrocatalytic activity of cerium oxide nanocrystals makes the nanocomposites as advanced, non-precious electrocatalysts for ORR.