Synthesis of all-biomass-derived carbon nanofibers for dual-functional filtration membranes and oxygen evolution reaction electrocatalysts

Abstract

We report a facile and eco-friendly approach to the synthesis of carbon nanofibers (CNFs), using cornstalks as carbon precursors and pinewood-derived carbon powders with inherent rough surfaces as catalytic substrates during chemical vapor deposition. Then, we annealed the CNFs in the presence of ammonia to impart them nitrogen doping (NCNFs), large surface areas, hydrophilicity and underwater oleophobicity. As a result, the NCNF networks achieved via vacuum filtration could work as oil/dye dual-functional filtration membranes for simultaneous removal of crude oil droplets, methylene blue and reactive violet K-3R from water with high flux up to 4950 L m−2 h−1, high efficiency of 99.82% and excellent recyclability. Finally, cobalt oxide (CoxOy) nanoparticles were deposited on NCNFs to prepare CoxOy/NCNF composites, which exhibited higher electrocatalytic activity (overpotential at current density of 10 mA cm−2: 290 mV) and better durability towards the oxygen evolution reaction than the state-of-the-art precious iridium oxide catalysts. This may be attributable to nitrogen doping, synergistic effect between CoxOy and NCNFs, as well as the superior structural and compositional stability of the CoxOy/NCNF composites.