Heterostructured MoO₃@CoWO₄ nanobelts towards high electrochemical performances via oxygen vacancies generation

Heterostructured nanomaterials tend to have a high proportion of oxygen vacancies (V_O) due to the presence of heterogeneous interfaces. Herein, a new kind of heterostructured MoO₃@CoWO₄ nanobelts was successfully evaluated as fascinating cathode material. SEM and TEM analysis indicated that the MoO₃ nanobelts were fully blanketed with CoWO₄ nanodots. The generation of Vo species was confirmed by XPS and EPR data. By profiting both synergistic and Vo generation effects, MoO₃@CoWO₄ electrode displayed an excellent capacitance of 246 mAh·g^-1 (1966 F·g^-1at 0.5 A·g^-1) with high-rate capability of 174 mAh·g^-1 (1394 F·g^-1 at 30 A·g^-1) as well as superb stability of 94 % (over 15,000 cycles). Notably, all-solid-state device delivered a good energy value of 63.1 Wh·kg^-1 at 375 W·kg^-1. Interestingly, the supercapacitor device showed super-low self-discharge comportment of only 12.1 % during 24 h. Importantly, the generation of the V_O defects could control the ions diffusion process and lead a sharp decrease in the self-discharge process.