Improving the oxygen evolution activity of Co3O4 by introducing Ce species derived from Ce-substituted ZIF-67

Efficient electrocatalysts based on abundant transition metals have emerged as important candidates for the oxygen evolution reaction (OER). Herein, significant improvement in OER performance has been achieved by using hierarchical nanostructured Ce–Co3O4 composites derived from Ce-substituted ZIF-67 precursors. Our results show that proper control of the introduced Ce amount and species could precisely tune the Co3+/Co2+ ratio and induce surface oxygen defects, further boosting the OER performance. Especially, the introduction of suitable Ce content (i.e., 6.44 wt% Ce) into the crystal structure and onto the surface of Co3O4 effectively facilitates the formation of Co3+ species and modifies the chemical binding energies, leading to much improved activity for OER with a 369 mV overpotential at 10 mA cm−2, a Tafel slope of 56 mV dec−1 and excellent long-term stability in 1.0 M KOH solution. These results demonstrate the efficient and feasible strategy for tailoring the electrocatalytic properties of metal oxides by Ce-doping and modification.