Interfacial Electronic Engineering in NiCo₂S₄@NiAl‑LDH Core-Shell Nanoarrays for Advanced Supercapacitor Electrodes

The rational design of heterostructured electrode materials with optimized interfacial charge transport and reaction kinetics is pivotal for advancing supercapacitor performance. Herein, we report a hierarchical core-shell nanoarray composed of conductive NiCo₂S₄ (NCS) nanoneedles as the core and NiAl‑layered double hydroxide (NALDH) nanosheets as the shell, directly grown on nickel foam. The NCS@NALDH electrode delivers an outstanding specific capacity of 244.8 mAh g^-1 (1762.4 F g^-1) at 2 A g^-1, superior rate capability (72.5% retention at 10 A g^-1), and remarkable cycling stability (91.4% capacity retention after 5000 cycles). Kinetics analysis identifies a surface-dominated charge storage mechanism with a significantly enhanced capacitive contribution. Combined experimental characterizations and theory calculations elucidate that a strong interfacial coupling triggers electron transfer from NALDH to NCS, creating a built‑in electric field and rendering the NALDH surface electron‑deficient. This electronic structure modulation optimizes the adsorption energy of OH^- intermediates and facilitates charge transfer, thereby fundamentally boosting the redox kinetics. This work demonstrates an effective strategy of interfacial electronic engineering through heterostructure construction and subtle composition tuning for developing high‑performance energy storage electrodes.