Selective silver recovery through single-pyrrolic nitrogen engineered carbon electrodes: A capacitive deionization...

Area of Science:

• Materials Science
• Environmental Science
• Electrochemistry

Background:

• Capacitive deionization (CDI) is a promising technology for water purification.
• Designing high-performance electrode materials is crucial for enhancing CDI efficiency.
• Understanding the role of dopants, like nitrogen, at an atomic level is key for material optimization.

Purpose of the Study:

• To investigate the specific role of single pyrrolic nitrogen in carbon materials for capacitive silver ion (Ag⁺) removal.
• To synthesize and characterize a single pyrrolic nitrogen-doped carbon material (SPNCM) for CDI applications.
• To provide atomic-level insights into the adsorption and charge transfer mechanisms.

Main Methods:

• Synthesis of SPNCM using a defluorination-mediated pyrolysis strategy.
• Electrochemical testing of SPNCM for Ag⁺ adsorption in AgNO₃ solutions.
• Evaluation of selectivity in mixed heavy metal solutions and cycling stability.
• Multiscale simulations and experimental validation.

Main Results:

• SPNCM achieved a high Ag⁺ adsorption capacity of 1538.8 mg/g with 99.63% removal efficiency at 2500 mg/L AgNO₃ and 0.8 V.
• The electrode demonstrated excellent Ag⁺ selectivity (ρ_M^Ag>15) in mixed heavy metal solutions.
• Capacity retention reached 95.05% after 25 adsorption-desorption cycles.
• Pyrrolic-N acted as an ideal site for Ag⁺ adsorption and charge transfer.

Conclusions:

• Single pyrrolic nitrogen significantly enhances Ag⁺ adsorption and charge transfer in carbon materials for CDI.
• SPNCM shows high efficiency, selectivity, and stability, indicating its potential for industrial wastewater treatment.
• This study provides fundamental insights for the rational design of nitrogen-doped carbon electrodes for CDI.