Lattice-compressed and N-doped Co nanoparticles to boost oxygen reduction reaction for zinc-air batteries

The development of high-activity non-noble metal catalysts for oxygen reduction reaction (ORR) is pretty necessary to popularize metal-air batteries. Controlling the surface strain of metal nanoparticles is one of the effective ways to boost their electrocatalytic activities by modifying the surface electronic structure. In this work, the N-doped carbon nanotube encapsulating lattice-compressed and N-doped Co nanoparticles (Co@NCNT) for ORR are prepared through the programmed carbonization with plasma etching treatment. The compressive strain on the Co (1 1 1) facet is regulated in individual nanoparticle through the plasma treatment. Moreover, the N-doped Co compound is found via the physical characterizations. In alkaline medium, the Co@NCNT exhibits more positive half-wave potential (0.866 V vs. RHE) and higher stability compared to the commercial 20% Pt/C (0.861 V vs. RHE). It also shows a competitive activity and superior stability for ORR in acid medium. The peak power density reaches 194.5 mW cm(-2) when the catalyst is used as the air cathode for zinc-air battery (ZAB). The excellent electrocatalytic performance of the Co@NCNT results from the synergistic effect of the N-doping and strain-tuning created by plasma. This work provides a facile method for synchronous large-scale synthesis and strain-tuning of catalytic materials without introducing adverse effects.