Precise design and in situ synthesis of hollow Co 9 S 8 @CoNi-LDH heterostructure for high-performance supercapacitors.

Layered double hydroxides (LDHs) and metal sulfides (MSs) have been widely used as promising electrode materials for supercapacitors, and the rational architectural design of MS/LDH heterogeneous structures is critical to optimize large energy storage. Herein, a precisely designed hollow Co 9 S 8 nanotubes@CoNi-LDH nanosheet heterostructure on Ni foam, facilely prepared by an ingenious in situ strategy in this Co 9 S 8 nanoarray was first used as the self-sacrificing template and metal source to in situ synthesize Co-ZIF-67 polyhedron to form the Co 9 S 8 @ZIF-67 heterostructure, and then Co 9 S 8 @ZIF-67 was in situ etched successfully using Ni 2+ ions to form the final Co 9 S 8 @CoNi-LDH/NF core-shell nanoarray. This in situ synthetic strategy to fabricate the heterostructure is conducive to boosting the structural stability, modifying the electric structure and regulating the interfacial charge transfer. Due to the synergistic effect and tight heterogeneous interface, Co 9 S 8 @CoNi-LDH/NF displayed an outstanding capacitance of 9.65 F cm -2 at a current density of 2 mA cm -2 and excellent capacitance retention rate of 91.7% after 5000 cycles. In addition, the ASC device assembled with AC has an extremely high energy density of 1.0 mW h cm -2 at 2 mA cm -2 and maintains 96.9% capacitance retention after 5000 cycles. This work provides a skillful strategy for the precise design and in situ synthesis of MS/LDH heterostructures with fascinating features for electrochemical energy storage applications.