Reactable ionic liquid in situ-induced synthesis of Fe3O4 nanoparticles modified N-doped hollow porous carbon microtubes for boosting multifunctional electrocatalytic activity

Abstract Oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are three paramount electrochemical processes for renewable energy conversion technologies consisting of fuel cells, metal-air batteries and water splitting devices. There remains a big challenge to fabricate low-cost and durable electrocatalysts with optimal catalytic performance for ORR, OER and HER. 3D hollow porous carbon based materials with attractive structural properties are usually constructed as promising candidates for electrocatalysis. Herein, we report a reactable ionic liquid (IL) in situ-induced synthesis of Fe3O4 nanoparticles decorated willow catkins derived N-doped 3D hollow porous carbon microtubes multifunctional electrocatalyst (Fe3O4/NCMTs-800(IL)). IL shows a huge advantage of control in synthesizing small size Fe3O4 nanoparticles, achieving uniform nanoparticles on hollow carbon microtubes owing to the interaction between the IL and carbon substrate. The Fe3O4/NCMTs-800(IL) electrocatalyst affords a positive half-wave potential for ORR, small overpotential for the OER and HER, and high stability for water splitting activity. The as-obtained electrocatalyst exhibits efficient and robust electrocatalytic performance can be ascribed to the special 3D porous structure and the synergistic effect of Fe3O4 and doped-N species. The approach indicates the great electrochemical energy applications for biomass and ionic liquids.