Ultrafine Co₃O₄ Nanoparticles within Nitrogen‐Doped Carbon Matrix Derived from Metal–Organic Complex for Boosting Lithium Storage and Oxygen Evolution Reaction

Transition metal oxides have recently received great attention for application in advanced lithium‐ion batteries (LIBs) and oxygen evolution reaction (OER). Herein, the ethylenediaminetetraacetic cobalt complex as a precursor to synthesize ultrafine Co 3 O 4 nanoparticles encapsulated into a nitrogen‐doped carbon matrix (NC) composites is presented. The as‐prepared Co 3 O 4 /NC‐350 obtained by pyrolysis at 350 °C demonstrates superior rate performance (372 mAh g −1 at 5.0 A g −1 ) and high cycling stability (92% capacity retention after 300 cycles at 1.0 A g −1 ) as anode for LIBs. When evaluated as an electrocatalyst for OER, the Co 3 O 4 /NC‐350 achieves an overpotential of 298 mV at a current density of 10 mA cm −2 . The NC‐encapsualted porous hierarchical structure assures fast and continuous electron transportation, high activity sites, and strong structural integrity. This works offers novel complex precursors for synthesizing transition metal–based electrodes for boosting electrochemical energy conversion and storage.