Dual plasma engineering of NiCoO(x) on defect-rich, nitrogen-doped, rambutan-like carbon for high-performance zinc-air batteries.

A dual-plasma engineering strategy is proposed to improve the inherent bifunctional oxygen electrocatalysis in zinc-air batteries (ZABs). Here, metal-organic framework (MOF)-derived rambutan-like (RL) carbon composites are first treated with N radio-frequency (RF) plasma to introduce abundant defects and nitrogen dopants, which significantly promote the adsorption and nucleation of NiCoO nanoparticles (NPs) by increasing binding energies and interfacial charge transfer at defect-rich N-doped carbon nanotube (NCNT) interfaces, as supported by density functional theory (DFT) calculations. Subsequent dielectric barrier discharge (DBD) plasma treatment further modulates the surface electronic structure by generating oxygen vacancies. DFT calculations show that these oxygen vacancies lower the reaction barriers for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), while the enrichment of higher-valence cations further promotes OER kinetics. The resulting DBD/NiCoO@p-RL catalyst delivers enhanced overall oxygen electrocatalytic performance, exhibiting an OER overpotential of 399 ± 8 mV at 20 mA cm and an ORR half-wave potential of 0.849 ± 0.007 V. When assembled into ZABs, it delivers peak power densities of 176.9 ± 1.2 mW cm in aqueous ZABs and 79.8 ± 0.7 mW cm in flexible all-solid-state ZABs, while maintaining long-term cycling and nearly invariant output potential under multiple bending states, highlighting plasma-driven defect and vacancy regulation as a powerful route to next-generation bifunctional oxygen electrocatalysts for ZABs.