Efficient Electronic Transport in Partially Disordered Co₃O₄ Nanosheets for Electrocatalytic Oxygen Evolution Reaction

The design and synthesis of high-performance electrocatalysts for the oxygen evolution reaction (OER) are critical factors for the development of electrochemical energy storage and conversion systems. Here, a remarkable enhancement in OER activity is reported by introducing cerium into Co₃O₄. An electrode made of Co_3-xCe_xO₄ requires a much lower overpotential than that of Co₃O₄ nanosheets to reach a current density of 100 mA cm^-2, and it is stable for at least 100 h with high intrinsic activity. The structure becomes partially disordered after Ce doping, thus exposing more active sites. In situ Raman spectra reveals a polyhedral distortion of Co₃O₄ accompanying the oxygen evolution process. Moreover, the active cobalt (oxy)hydroxide phase in Co_3-xCe_xO₄ appears at lower bias as compared with Co₃O₄. It is proposed that the enhanced activity is ascribed to the structural disorder and electronic transport after the introduction of cerium.