Curvature enhanced NH₂-MIL-53(Al) electrode for boosting ion diffusion and capacitive deionization defluorination.

Area of Science:

• Materials Science
• Environmental Engineering
• Electrochemistry

Background:

• Traditional capacitive deionization (CDI) materials struggle with low fluorine adsorption capacity (FAC) due to limitations in specific surface area and chemical composition.
• Modulating local electric field strength (LEF) by altering material curvature presents a promising strategy for enhanced ion storage.

Purpose of the Study:

• To investigate the direct relationship between material curvature and CDI performance.
• To develop a novel method for preparing electrode materials with varying curvatures but similar specific surface areas.

Main Methods:

• A modulator-based curvature modulation method was used to synthesize three NH2-MIL-53(Al) electrode morphologies with distinct curvatures.
• The fluoride removal capacity, rate, and cycle stability of these materials were evaluated using CDI.

Main Results:

• The urchin-like electrode (NCMOF-3) with high surface curvature demonstrated an ultra-high fluoride removal capacity (61.29 mgNaF g-1) and a fast removal rate.
• The material exhibited excellent charging/discharging cycle stability over 10,000 cycles, outperforming previously reported MOF electrodes.
• Higher surface curvature correlated with increased ion distribution concentration and enhanced local electric field enhancement (LEFE).

Conclusions:

• Material surface curvature directly impacts CDI performance, offering a new design paradigm beyond specific surface area optimization.
• High surface curvature enhances LEFE, leading to increased ion storage capacity and diffusion rates in CDI.
• This study provides novel design insights for next-generation CDI materials through curvature structure engineering.