Highly dispersed Co4N nanoparticles coated by g-C3N4 nanotube: An active bifunctional electrocatalyst for oxygen reduction and oxygen evolution reaction

Developing a cost-effective, efficient, and facile prepared electrocatalyst for oxygen reduction (ORR) and evolution reaction (OER) is critical for a range of renewable energy technologies. Herein, we report unique Co4N nanoparticles loading on g-C3N4 nanotubes (Co4N@CNNT) bifunctional electrocatalyst for OER and ORR by an in-situ method. Highly dispersed Co4N nanoparticles as the active sites gather at the top of the g-C3N4 nanotube (CNNT), while the six-fold cavities from smooth CNNT with an outer diameter of 48 nm and an inner diameter of 22 nm act as anchor sites to preferentially coordinate with the active sites. Benefiting from the distinctive structure features, the intrinsic metallic Co4N@CNNT exhibits high electrocatalytic performances. Electrochemistry studies show that an onset potential of 0.94 V and a half-wave potential of 0.86 V of Co4N@CNNT are obtained that are superior to Pt/C catalyst. A low overpotential of 285 mV at an anodic current density of 10 mA cm-2 during the OER process is obtained that is superior to the IrO2 catalyst; and lower Tafel plot and good durability are also observed. Our findings provide a new strategy for the fabrication of an efficient bifunctional electrocatalyst for OER and ORR.