Nitrogen and fluorine dual-doped porous graphene-nanosheets as efficient metal-free electrocatalysts for hydrogen-evolution in acidic media

Abstract

Nitrogen and fluorine dual-doped porous graphene-nanosheets (NFPGNS) with pyridinic N doped rich configurations have been synthesized by a simple ion adsorption and chemical-etching method. Higher graphitization degree of NFPGNS was in favor of charge transfer and mass transfer. Moreover, higher surface areas and various pore structures of NFPGNS were found to be beneficial for the accessment of active sites. Therefore, efficient catalytic activity towards the hydrogen evolution reaction (HER) with the onset overpotential of only ∼150 mV and superior stability has been investigated on the NFPGNS electrocatalysts. Doping of F evidently promotes the catalytic activity of N containing carbon materials for the HER. Further density functional theory (DFT) calculations have revealed the heteroatoms multi-doping effect on NFPGNS that leads to a lowest Gibbs free energy and stronger strength of H adsorption, thereby favoring the HER catalytic activity.