Self-sacrificing MOF-74 to amorphous CoMoS4 hollow tube with nanosheet surface for high stability supercapacitors

Designing high-performance electrodes and elucidating their energy storage mechanisms are crucial for supercapacitors. In this study, an in situ conversion method is firstly employed to transform CoCH (Co(CO3)0.5(OH)center dot 0.11 H2O) into Co-MOF-74 nanorods, which serves as a self-sacrificial template. Subsequently, the amorphous CoMoS4 hollow tube arrays with self-assembled nanosheet surfaces are obtained through MoO42- etching and S2exchange. Benefiting from the nanosheets-coated hollow tubular structure and amorphous characteristics, CoMoS4 exhibits a high areal capacitance of 7.01 F center dot cm- 2 at 2 mA center dot cm- 2 and 91.81 % retention after 5000 cycles. When further assembled into a hybrid supercapacitor, the CoMoS4//AC device exhibits excellent performance with the energy density of 0.684 mWh center dot cm- 2 at 1.876 mW center dot cm- 2 and 91.39 % retention after 10000 cycles. Furthermore, the mechanism study reveals that Mo- and S-doped amorphous CoOOH is a genuine energy storage material. This work provides valuable insights into the preparation of amorphous materials using the selfsacrificial template transformation method and the understand of their energy storage mechanisms.