In Situ Fabricating Oxygen Vacancy-Rich TiO₂ Nanoparticles via Utilizing Thermodynamically Metastable Ti Atoms on Ti₃C₂Tx MXene Nanosheet Surface To Boost Electrocatalytic Activity for High-Performance Li–O₂ Batteries

Catalysts with high performance are urgently needed in order to accelerate the reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in lithium–oxygen (Li–O2) batteries. Herein, utilizing thermodynamically metastable Ti atoms on the Ti3C2Tx MXene nanosheet surface as the nucleation site, oxygen vacancy-rich TiO2 nanoparticles were in situ fabricated on Ti3C2Tx nanosheets (V-TiO2/Ti3C2Tx) and used as the oxygen electrode of Li–O2 batteries. Oxygen vacancy (Vo) can boost the migration rate of electrons and Li+ as well as act as the active sites for catalyzing the ORR and OER. Based on the above merits, V-TiO2/Ti3C2Tx-based Li–O2 battery shows improved performance including the ultralow overpotential of 0.21 V, high specific capacity of 11 487 mA h g–1 at a current density of 100 mA g–1, and excellent round-trip efficiency (93%). This work proposes an effective strategy for researching high-performance oxygen electrodes for Li–O2 batteries via introducing Vo-rich oxides on two-dimensional MXene.