Fe/Ni-Doped Co5.47N Nanoparticles Integrated on Nitrogen-Doped Vertical Reduced Graphene Oxide Arrays for Overall Water Splitting in Wide pH Range

Abstract

It is necessary to rationally develop iron group metal nitrides with noble-metal-like electronic structures as catalysts for water splitting. Here we report a novel electrocatalyst consisting of Fe/Ni-doped Co5.47N Nanoparticles integrated with N-doped vertically reduced graphene oxide arrays (N-VrGO) (Fe, Ni-Co5.47N@N-rGO) for overall water splitting. The suitable amount of metal addition, the vertical structure of N-VrGO, and the synergistic effect of N in N-VrGO and N in Fe, Ni-Co5.47N result in the enhanced electrocatalytic performance of Fe, Ni-Co5.47N@N-VrGO-2 catalyst in a wide pH range. It has lower overpotentials for hydrogen evolution reactions (94 mV, 121 mV) and oxygen evolution reactions (234 mV, 318 mV) in 1 M KOH and 0.5 M H2SO4 electrolytes, respectively. The Fe, Ni-Co5.47N@N-VrGO-2 catalyst exhibits a good Faraday efficiency (about 90%) and outstanding stability (over 12 h). The synergistic effect of N in N-VrGO and N in Fe, Ni-Co5.47N promotes the electron rearrangement on the metal surface and further enhances the electrocatalytic performance of the catalyst. This work helps to better understand the synergistic interaction between iron group metal compounds and heteroatom-doped VrGO, and helps to more rationally select the substrates for iron group metal compounds.