Ni nanoparticles embedded in multi-channel carbon nanofibers: Self-supporting electrodes for bifunctional catalysis of hydrogen and oxygen evolution reactions

Nitrogen-doped carbon nanofibers with multi-channels loaded with nanoscale nickel particles (Ni-MNCNF) were achieved by the combination of coaxial electrospinning and pyrolysis. Which was used as a self-supporting electrode for electrochemical hydrogen and oxygen evolution reactions. The multi-channels of the fiber facilitated the fast mass transfer as well as endowed it with more exposed active sites. In addition, nanoscale Ni crystals were dispersed evenly on the fiber walls due to the confinement effect of carbon materials. Furthermore, carbon nanofibers provided an excellent conductive network, which expedited the charge transfer rate and further enhanced catalytic activity. At a current density of 10 mA cm−2, the overpotentials for the hydrogen evolution reaction (HER) were only 65 mV and 203 mV in alkaline and acidic electrolytes, respectively, and the overpotential for the oxygen evolution reaction (OER) was 193 mV in an alkaline electrolyte, promoting its potential industrial applications and reducing the negative impact on the environment. This research presented a strategy for designing self-supporting transition metal-based catalysts with superior activity. •Multi-channel carbon nanofibers were synthesized as self-supporting electrodes.•Uniform distribution of nanoscale Ni crystals on fiber walls provided abundant active sites for electrocatalysis.•Ni-MNCNF exhibited superior bifunctional catalytic performance for both hydrogen and oxygen evolution reaction.