Fe-doped Co₃O₄ anchored on hollow carbon nanocages for efficient electrocatalytic oxygen evolution

In this work, a Fe-doped Co₃O₄ OER electrocatalyst supported by an N-doped hollow nanocage carbon framework (Fe-Co₃O₄/NC) was successfully prepared by anion exchange and annealing in an air atmosphere strategy. XRD and HRTEM characterizations confirm that Fe the incorporation of Fe into the lattice of Co₃O₄. XPS characterization clarifies that the valence state of Co increases after the introduction of Fe, which originates from the electrons transfer from Co²⁺/Co³⁺ to Fe³⁺ and is induced by the valence electron configuration of cations. It simulates Co sites in-situ derived into CoOOH active species during the OER process, which is confirmed by the HRTEM and XPS characterization after the OER stability test. Electrochemical performance tests show that the Fe-Co₃O₄/NC electrocatalyst only exhibits 275 mV overpotential to achieve a current density of 10 mA/cm² and stably maintains for 20 h at 100 mA/cm². Together with 20% Pt/C electrocatalyst, the composed two-electrode system only needs 2.041 V applied potential to achieve 100 mA/cm² for total water splitting in a self-made membrane electrode device, which has industrial application prospects.