Non-precious metal nanoparticles supported on nitrogen-doped graphene as a promising catalyst for oxygen reduction reaction: Synthesis, characterization and electrocatalytic performance

Abstract

Nitrogen-doped graphene (NG) based non-precious metal catalysts is used as a catalyst for oxygen reduction reaction (ORR). Nanoflower-like NG with designed nitrogen types is directly synthesized using a low temperature solvothermal process and then Fe, Co and Fe–Co nanoparticles are precipitated onto the NG using a modified polyol method. The morphology of the NG is studied using scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The synthesized M/NG (M = Fe, Co, Fe–Co) electrocatalysts are characterized using transmission electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Electrochemical characterizations reveal that NG acts as a catalyst for ORR in an alkaline solution. The electrocatalytic properties of NG and M/NG catalysts are investigated for ORR in 0.1 M KOH. Cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy are used to measure electrocatalytic activity. M/NG catalysts exhibit higher electrocatalytic activity than NG and the highest activity is observed for the Co/NG electrode. Chronoamperometric results demonstrate that the Co/NG catalyst is more stable than commercial Pt/C for ORR in an alkaline solution.