ZnO-activated NiCo-LDH/MoS2 heterostructure for high-capacity supercapattery devices and efficient oxygen evolution

초록

The development of multifunctional electrode materials that combine superior charge-storage capability with effective electrocatalytic performance remains critical for advanced energy-storage and water-splitting systems. In this work, a ternary NiCo-LDH/MoS2@ZnO hybrid composite was constructed via a hydrothermal co-assembly strategy and investigated for its bifunctional electrochemical utility in asymmetric supercapattery assemblies and alkaline OER applications. The NiCo-LDH component supplied abundant Faradaic redox-active Ni/Co sites, MoS2 provided layered ion-diffusion pathways, and ZnO improved interfacial contact and structural reinforcement within the hybrid architecture. Characterization of the material's structure and surface morphology established the development of a crystalline, porous heterostructure with an interconnected network of improved surface accessibility and a notably lower charge-transfer resistance than that observed for each individual component. Electrochemical testing in a three-electrode cell showed that the NiCo-LDH/MoS2@ZnO electrode achieved specific capacities of 1832 C g- 1 from CV measurements at 10 mV/s and 2743 C g- 1 from GCD tests at 2.0 A g- 1. An asymmetric NiCo-LDH/MoS2@ZnO//activated carbon device delivered specific capacity of 376 C g- 1 at 10 mV/s and 452 C g- 1 at 2.0 A g- 1. Furthermore, the device achieved an energy density of 86.2 Wh kg- 1 at a power density of 1800 W kg- 1, together with 84.4% capacity retention and 92.8% Coulombic efficiency after 5000 charge-discharge cycles. Analysis of the electrochemical kinetics disclosed a dual charge-storage character, wherein battery-type diffusion-governed Faradaic contributions and surface-kinetics-regulated capacitive responses operate simultaneously. Under alkaline OER conditions in 1.0 M KOH, achieving the benchmark current density of 10 mA cm- 2 demanded an overpotential of only 235.7 mV, while the corresponding Tafel slope was determined to be 74.82 mV dec- 1. This enhanced electrochemical response is attributed to the synergistic interaction among NiCo-LDH, MoS2, and ZnO, which enhances active-site exposure, ion transport, and interfacial charge-transfer kinetics. Collectively, these outcomes position NiCo-LDH/MoS2@ZnO as a promising multifunctional electrode platform suitable for deployment in advanced hybrid supercapattery assemblies and alkaline OER electrocatalytic devices.

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