A facile approach to tailoring electrocatalytic activities of imine-rich nitrogen-doped graphene for oxygen reduction reaction

Abstract

We report efficient modulation of the electrocatalytic activity of imine-rich nitrogen-doped graphene nanosheets (IRnGs) in the oxygen reduction reaction (ORR) by chemical functionalization. IRnGs are prepared by a simple acid-catalyzed dehydration reaction between graphene oxide and aniline derivatives. Various electron-donating and electron-withdrawing substituents are introduced in the para-position of aniline to afford diverse IRnG electrocatalysts. Cyclic voltammetry and rotating ring disk electrode measurements show that the electrocatalytic activity of IRnGs for ORR is highly sensitive to the electronic characteristics of functionalities present in their chemical structures. Thus, the above ORR activities are significantly improved by increasing the electron-withdrawing capability of substituents, since this promotes the beneficial polarization of electrocatalytically active imine bond ([sbnd]C[dbnd]N[sbnd]) in IRnGs. In addition, metal-free IRnGs electrocatalysts offer additional advantages of high selectivity, good long-term stability and excellent tolerance to methanol crossover for ORR in alkaline solution.