Laser Shock Fabrication of Nitrogen Doped Inverse Spinel Fe3 O4/Carbon Nanosheet Film Electrodes towards Hydrogen Evolution Reactions in Alkaline Media

Abstract

The reliable and cost-effective production of high-performance film electrodes for hydrogen evolution reactions remains a challenge for the laser surface modification community. In this study, prior to a thermal imidization reaction, a small number of Fe3 O4 nanoparticles were vortexed into a poly(amic acid) (PAA) prepolymer, and the achieved flat composite film was then ablated by a 1064 nm fiber laser. After laser irradiation, the hierarchical architectures of carbon nanosheets decorated with Fe3 O4 nanoparticles were generated. Although pure polyimide (PI) film and laser carbonized PI film, as well as bare Fe3 O4, showcase poor intrinsic catalytic activity toward alkaline hydrogen evolution reactions, our laser-derived Fe3 O4/carbon nanosheet hybrid film demonstrated enhanced electrocatalytic activity and stability in 1 M KOH electrolyte; the overpotential(η10) reached 247 mV when the current density was 10 mA cm−2 with a slight current decay in the chronoamperometric examination of 12 h. Finally, we proposed that the substitution of N to O in Fe−O sites of trans spinel structured magnetite would be able to modulate the free energy of hydrogen adsorption (∆GH*) and accelerate water dissociation.