Functional interface optimizing Ni foam substrate for in situ construction of layered bimetallic ZnCo hydroxide for highly enhanced electrochemical performance

Ni foam (NF) is widely employed as a binder-free electrode substrate owing to its high porosity and excellent conductivity. However, its inherent limitations, such as low specific surface area and negligible intrinsic capacitance, constrain the overall electrochemical performance. To overcome these drawbacks, we developed a chemical modification strategy that combined in-situ Fe etching, Co doping and sulfur ion-exchange to regulate the NF. The resulting substrate, denoted as NC 2/3 F 4/3 -S 0.5 , features a honeycomb-like (Fe, Co)-doped Ni 3 S 2 array structure. This architecture simultaneously provides enlarged specific surface area and enhanced OH − adsorption capacity, thereby contributing to a significantly improved electrochemical active surface area and intrinsic capacitance. Consequently, NC 2/3 F 4/3 -S 0.5 serves as an ideal scaffold for the subsequent electrodeposition of ZnCo-layered double hydroxide (ZnCo-LDH), enabling the construction of an integrated, binder-free ZnCo-LDH/NC 2/3 F 4/3 -S 0.5 electrode. Owing to the synergistic effect between NC 2/3 F 4/3 -S 0.5 and redox-active ZnCo-LDH, the optimized electrode delivered a remarkable areal capacitance of 13.68 F/cm 2 at 3 mA/cm 2 . Furthermore, a hybrid supercapacitor (HSC) assembled with this positive electrode and an activated carbon negative electrode achieved a high energy density of 350 μWh/cm 2 at a power density of 2270 μW/cm 2 . This work not only provides a highly efficient ZnCo-LDH/NC 2/3 F 4/3 -S 0.5 binder-free electrode but also demonstrates the critical role of synergistic effect between a multinary sulfide scaffold and a layered double hydroxide for advanced supercapacitors.