Mechanistic insights into d-band center engineering and interfacial charge transfer in ternary heterostructures for...

Herein, we demonstrate a strategically orchestrated synthesis of a hierarchical NiCo-LDH/CuS/Cu(OH)₂ ternary heterostructure for high-performance supercapacitors. This unique core-shell architecture, constructed via in-situ sulfidation and subsequent electrodeposition, leverages synergistic enhancement mechanisms: the conductive CuS interlayer establishes superb electrical connectivity and a built-in electric field for accelerated charge transfer, while vertically aligned NiCo-LDH nanoflakes provide abundant active sites for efficient Faradaic reactions. The optimized electrode delivers an ultrahigh areal capacitance of 22.2 F cm^-2 with outstanding rate capability, and the assembled device achieves a remarkable energy density of 0.295 mWh cm^-2, excellent cycling durability, superior charge retention with suppressed self-discharge (0.33 V after 120 h), and an ultralow leakage current of 0.69 μA. Complementary DFT calculations reveal that the ternary heterostructure exhibits enhanced density of states near the Fermi level, modulated d-band centers identifying Co and Ni as primary OH^- adsorption sites, pronounced interfacial charge redistribution confirming built-in electric fields, and a significantly higher OH^- adsorption energy, collectively elucidating the electronic origins of the superior conductivity, charge transfer kinetics, and reaction thermodynamics.