Oxygen vacancy-based ultrathin Co3O4 nanosheets as a high-efficiency electrocatalyst for oxygen evolution reaction

Enhancing the catalytic activity of Co 3 O 4 electrocatalysts featuring abundant oxygen vacancies is required to enable their application in oxygen evolution reaction (OER). However, developing a harmless defect engineering strategy based on mild conditions to realize such an enhancement remains a challenge. Here, ultrathin Co 3 O 4 nanosheets with abundant oxygen vacancies were prepared through a simple two-step method comprising a hydrothermal process and pre-oxidation to study the catalytic activity of the nanosheets toward OER. The ultrathin sheet structure and the Co 3 O 4 nanosheets surface provide abundant active sites. The oxygen vacancy not only improves the catalyst activity, but also improves the electron transfer efficiency. These advantages make ultrathin Co 3 O 4 nanosheets with abundant oxygen vacancies an excellent electrocatalyst for oxygen evolution. In an alkaline medium , ultrathin Co 3 O 4 nanosheets exhibited excellent OER catalytic activity, with a small overpotential (367 mV for 10 mA/cm 2 ) and faster reaction kinetics (65 mV/dec).Moreover, the electrocatalyst still maintained 68% of its original catalytic activity after 24 h operation. This work provides an extensive and reliable method for the preparation of low-cost and highly efficient OER electrocatalysts.