Balancing Activity and Stability in Spinel Cobalt Oxides through Geometrical Sites Occupation towards Efficient Electrocatalytic Oxygen Evolution

Designing active and stable oxygen evolution reaction (OER) catalysts are vitally important to various energy conversion devices. Herein, we introduce elements Ni and Mn into (Co)(tet)(Co-2)(oct)O-4 nanosheets (NSs) at fixed geometrical sites, including Mn-oct, Ni-oct, and Ni-tet, to optimize the initial geometrical structure and modulate the CoCo2O4 surface from oxygen-excess to oxygen-deficiency. The pristine (Ni,Mn)-(Co)(tet)(Co-2)(oct)O-4 NSs shows excellent OER activity with an overpotential of 281.6 mV at a current density of 10 mA cm(-2). Moreover, without damaging their initial activity, the activated (Act)-(Ni,Mn)-(Co)(tet)(Co-2)(oct)O-4 NSs after surface reconstruction exhibit long-term stability of 100 h under 10 mA cm(-2), 50 mA cm(-2), or even 100 mA cm(-2). The optimal balance between electroactivity and stability leads to remarkable OER performances, providing a pivotal guideline for designing ideal electrocatalysts and inspiring more works to focus on the dynamic change of each occupation site component.

Automated summary

Designing active and stable oxygen evolution reaction catalysts is crucial for various energy conversion devices. By introducing Ni and Mn elements and optimizing the geometrical structure, the catalyst surface can be modulated from oxygen-excess to oxygen-deficiency, resulting in excellent OER activity and long-term stability.