Synergistic Surface Reconstruction and Interface Engineering in Bimetallic Selenides: Advancing Renewable Energy Storage and Oxygen Evolution

Designing a bimetallic selenide-based heterostructure that possesses high catalytic efficiency, high capacity, and rate capability remains challenging due to constraints imposed by slow reaction kinetics, inadequate electrode utilization, and significant volume deformation. In this study, we successfully engineer a heterostructure comprising carbon nanotubes intertwined with sea urchin-like Bi₂Se₃@NiSe₂ nanostructures having high electronic conductivity, high specific capacity, sufficiently exposed active sites, and favorable charge carrier migration. The interface engineering of the multilevel Bi₂Se₃@NiSe₂ nanostructure on the carbon nanotube (CNT) framework synergistically reduces energetic barriers and accelerates oxygen evolution kinetics as well as promotes faster Faradaic reactions to enhance charge storage. As a consequence, the as-designed flexible supercapacitor device (Bi₂Se₃@NiSe₂-CNT/CTs//AC-CNT/CTs) attains a peak energy density of 75.93 Wh kg^-1 and a maximum power density of 15.12 kW kg^-1, demonstrating remarkable durability (94.35% capacitance retention) after 40k cycles. The higher density of states near the Fermi level in the Bi₂Se₃@NiSe₂ hybrid enhances electronic conductivity and charge carrier mobility, coupled with efficient OH^- adsorption (ΔE_a = -4.352 eV@Bi site, ΔE_a = -4.932 eV@Ni site), thereby trapping more electrolyte ions and promoting faster redox reactions. Additionally, the induced electronic interactions between core selenides and surface-generated thin layers of hydroxide/oxide synergistically accelerate the reaction kinetics in terms of a lower overpotential (199 mV@20 mA cm^-2), a lower Tafel slope (59.2 mV dec^-1), and a higher electrochemical surface area (1460.0 cm²) toward oxygen evolution. The proposed study on the construction of dual redox-active site heterostructures is expected to create avenues for advancing renewable energy systems.