Synergistic Engineering of Defects and Architecture in a Co@Co3O4@N-CNT Nanocage toward Li-Ion Batteries and HER

The design and synthesis of hollow and porous nanostructured electrode materials is an effective strategy to improve the electrochemical performance of lithium-ion batteries and the hydrogen evolution reaction (HER). Herein, we synthesize hollow and porous Co@Co3O4 nanoparticles embedded in N-doped CNTs (N-CNTs) with rich surface defects through a two-step calcination strategy. The formation mechanism is explored. The influence of oxygen vacancies regulated by the nanoscale Kirkendall effect on the electrochemical performance of the electrode is elucidated. The Co@Co3O4@ N-CNTs exhibit remarkable activity for catalyzing the HER with a low onset overpotential of 296 mV (a low Tafel slope of 116.2 mV dec-1), much better than Co3O4@N-CNTs (315 mV for overpotential and 124.2 mV dec-1 for Tafel slope). Significantly, the Co@Co3O4@N-CNTs deliver a high discharge capacity of 990 mA h g-1 after 600 cycles at 0.1 A g-1. Our nanostructure strategy can provide new insights into the strategy for high-rate and highly stable energy storage systems.

Automated summary

The design and synthesis of hollow and porous nanostructured electrode materials is an effective strategy to improve the electrochemical performance of lithium-ion batteries and the hydrogen evolution reaction (HER). The formation mechanism and the influence of oxygen vacancies regulated by the nanoscale Kirkendall effect on the electrochemical performance of the electrode are explored. The Co@Co3O4@N-CNTs exhibit remarkable activity for catalyzing the HER and deliver a high discharge capacity after 600 cycles, showcasing potential for high-rate and highly stable energy storage systems.