Synthesis of Multiporous Carbons from the Water Caltrop Shell for High-Performance Supercapacitors.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Chemistry

Background:

• Agricultural waste valorization is crucial for sustainable materials development.
• Developing high-performance electrode materials for energy storage is an ongoing challenge.
• Water caltrop shell (WCS) is an abundant agricultural byproduct with potential for carbon material synthesis.

Purpose of the Study:

• To develop an economic, sustainable, and green method for synthesizing multiporous carbons from WCS.
• To investigate the structural properties and tunable porosity of the synthesized carbons.
• To evaluate the electrochemical performance of WCS-derived multiporous carbons for supercapacitor applications.

Main Methods:

• Carbonization of WCS using a top-lit-updraft method to produce microporous biochar.
• Solvent-free physical blending of biochar with ZnO or CaCO3 nanoparticles and KOH as activating agents.
• High-temperature activation (900 °C) to create multiporous carbons with tunable micropore/mesopore ratios.

Main Results:

• Synthesized WCS multiporous carbons exhibit high surface areas (1175-1537 m² g⁻¹).
• Achieved carbon yield up to 50% with tunable micropore/mesopore surface area ratios.
• Electrodes demonstrated high specific capacitance (128 F g⁻¹ with ZnO, 102 F g⁻¹ with CaCO3) and good rate capability in supercapacitors.

Conclusions:

• The developed method offers an eco-friendly route to high-value multiporous carbons from agricultural waste.
• WCS-derived multiporous carbons are promising electrode materials for high-performance supercapacitors.
• Tunable porosity and high surface area contribute to excellent electrochemical energy storage capabilities.