Tunable Cationic Vacancies of Cobalt Oxides for Efficient Electrocatalysis in Li–O2 Batteries.

Vacancy engineering is one of the most effective strategies to introduce defects for improving electrocatalytic activities of cobalt oxides. Recent intensive research has been conducted to introduce oxygen vacancies for boosting Li–O2 battery performance. However, it is difficult to examine the efficiency of cationic vacancies due to their complicated preparation. Herein, a feasible method is demonstrated to introduce cationic vacancies into cobalt oxides via the thermal treatment of glycerolatocobalt (GlyCo) nanostructure. The formation of GlyCo composed of the repeating CoOCoO units provides the possibility to regulate the ratio between cobalt and oxygen, thus cobalt vacancies in cobalt oxides can be easily created by the thermal treatment. The presence of cobalt vacancies enables the regulation of electronic structure and charge‐transport properties of cobalt oxides with abundant defects on the basis of the experimental results and theoretical calculations, thus improving electrocatalytic activities. Therefore, the Li–O2 battery delivers superior electrochemical performance with large specific capacities of 13 331/12 040 mAh g−1, low overpotentials for the oxygen evolution reaction/oxygen reduction reaction of 1.15/0.23 V and good cycling stability. This work provides a favorable method to create metal vacancies for improving catalytic efficiency of advanced energy materials. [ABSTRACT FROM AUTHOR]