Atomic-Thick TiO2(B) Nanosheets Decorated with Ultrafine Co3O4 Nanocrystals As a Highly Efficient Catalyst for Lithium-Oxygen Battery.

Development of highly efficient catalysts based on transition metal oxides (TMOs) is desirable and remains a big challenge for lithium-oxygen (Li-O2) batteries. In the present work, atomic-thick TiO2(B) nanosheets decorated with ultrafine Co3O4 nanocrystals (Co3O4-TiO2(B)) were synthesized and utilized as cathode catalyst in Li-O2 batteries by designing a hybrid and inducing oxygen vacancies. The XPS characterization results suggested that the introduction of Co3O4 nanocrystals could induce numerous oxygen vacancies in the TiO2(B) nanosheets through Co doping in the hybrid catalyst. The subsequent electrochemical experiments indicated that the Li-O2 batteries with the prepared hybrid catalysts showed high specific capacity (11000 mAhg-1), and good cycling stability (200 cycles at a limited capacity of 1000 mAhg-1) with low polarization (above 2.7 V for discharge medium voltage and below 4.0 V for charge medium voltage within 80 cycles). Furthermore, a possible working mechanism was proposed for a better understanding of the high performance of Co3O4-TiO2(B) catalysts for the Li-O2 batteries. This work also provided new insights into designing efficient catalysts through interface engineering between 2D (two-dimensional) TMOs and 0D (zero-dimensional) TMOs for Li-O2 batteries or other catalysis-related fields.