Rationally designed NiMn LDH@NiCo₂O₄core-shell structures for high energy density supercapacitor and enzyme-free...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing bifunctional electrodes for supercapacitors and sensors is crucial but challenging.
• Existing electrodes often lack multifunctionality and possess simple structures, limiting their applications.
• Heterostructure design is a promising strategy to enhance electrochemical performance.

Purpose of the Study:

• To synthesize and characterize a novel bifunctional electrode material for supercapacitor and enzyme-free glucose sensing applications.
• To investigate the electrochemical performance of a core-shell NiMn layered double hydroxide (LDH)@NiCo2O4 heterostructure grown on carbon cloth (CC).
• To explore the synergistic effects of multi-metal composition and core-shell architecture on electrode performance.

Main Methods:

• In situ growth of NiCo2O4 nanowires as the core and NiMn LDH as the shell on carbon cloth (CC) to form a NiMn LDH@NiCo2O4/CC heterostructure.
• Systematic electrochemical characterization including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.
• Assembly of an asymmetric supercapacitor using the developed electrode and evaluation of its energy and power density, and cycle stability.
• Application of the electrode as an enzyme-free glucose sensor to assess sensitivity, detection range, and limit of detection.

Main Results:

• The NiMn LDH@NiCo2O4/CC core-shell electrode exhibited superior specific capacitance (2.40 F cm-2) and rate capability (76.22% at 20 mA cm-2) compared to single-component electrodes.
• An asymmetric supercapacitor assembled with this electrode demonstrated a high energy density (47.74 Wh kg-1 at 175 W kg-1) and excellent cycle stability (93.48% after 6000 cycles).
• As an enzyme-free glucose sensor, the electrode achieved high sensitivity (2139 μA mM-1 cm-2), a wide detection range, and a low detection limit (210 nM) with good anti-interference capabilities.

Conclusions:

• The rationally designed core-shell heterostructure significantly enhances electrochemical performance through improved electronic interaction and increased active surface area.
• The synergistic effect between NiCo2O4 and NiMn LDH is critical for achieving high-efficiency bifunctional electrode performance.
• This study highlights the potential of multi-metal synergy and advanced nanostructure engineering for developing next-generation energy storage and sensing devices.