Heterogeneous structured MoSe2–MoO3 quantum dots with enhanced sodium/potassium storage

Herein, quantum dot-assisted self-assembled MoSe2–MoO3 with a porous structure is synthesized via a MOF-directed strategy involving a thermal-induced reaction with Se. As an anode material for sodium ion batteries, due to inheriting the chemical activity of quantum dots and physical stability of the porous heterogeneous structure, it exhibits an outstanding electrochemical performance (i.e., 400 mA h g−1 after 500 cycles at a current density of 0.1 A g−1 with a capacity retention of 90% and 218.5 mA h g−1 after 2000 cycles at 3.0 A g−1 with a capacity retention of almost 100%) superior to that of MoSe2–MoO3 with different ratios and the traditional bulk MoSe2. Moreover, the improved potassium-ion storage of the anode is obtained (i.e., 308.7 mA h g−1 with a capacity retention of 97.9% after 300 cycles at 0.05 A g−1). This work paves the way for developing high-performance anode materials with a large reversible capacity and a long cycle-life for sodium/potassium ion batteries.