Photo-supercapacitors based on nanoscaled ZnO.

Area of Science:

• Materials Science
• Energy Storage
• Nanotechnology

Background:

• Zinc oxide (ZnO) is a versatile semiconductor with potential in energy storage devices.
• Photo-supercapacitors (P-SCs) offer enhanced performance under illumination.
• Understanding the influence of material morphology and defects is crucial for optimizing P-SC performance.

Purpose of the Study:

• To synthesize ZnO powders in nanowire (NW) and nanoflower (NF) morphologies.
• To evaluate the performance of P-SCs fabricated using these ZnO morphologies.
• To investigate the correlation between ZnO defect structures and P-SC performance.

Main Methods:

• Hydrothermal synthesis of ZnO nanowires and nanoflowers.
• Fabrication of P-SC devices using drop-casting on various substrates.
• Characterization using electron paramagnetic resonance, photoluminescence, and transmission electron microscopy.

Main Results:

• ZnO nanowire-based P-SCs exhibited a 3x increase in Coulombic efficiency under UV light, while nanoflower-based P-SCs showed a 1.7x increase.
• Nanowire morphology showed superior performance due to lower core defect density compared to nanoflowers.
• NF-based P-SCs achieved a promising energy density of 78.1 mWh kg⁻¹, with excellent capacitance retention (~100% over 3000 cycles).

Conclusions:

• ZnO morphology significantly impacts P-SC performance, with nanowires outperforming nanoflowers due to reduced defects.
• The developed P-SCs are stable, adaptable for large-area applications, and suitable for next-generation energy storage.
• These findings highlight the potential of ZnO nanostructures for efficient light-harvesting energy storage systems.