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

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.