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

Elucidating the role of single pyrrolic nitrogen in carbon materials for capacitive deionization (CDI) enables precise design of high-performance electrode materials. We synthesized single pyrrolic nitrogen-doped carbon material (SPNCM) using a defluorination-mediated pyrolysis strategy to investigate its role in capacitive Ag⁺ removal. In 2500 mg/L AgNO₃ solution at 0.8 V, the SPNCM electrode achieved an exceptional Ag⁺ adsorption capacity of 1538.8 mg/g with 99.63 % removal efficiency. The electrode maintained outstanding Ag⁺ selectivity (ρ_M^Ag>15) in mixed heavy metal solutions, demonstrating feasibility for industrial wastewater extraction. After 25 adsorption-desorption cycles in mixed solutions, capacity retention reached 95.05 %. Multiscale simulations and experiments reveal that the pyrrolic-N five-membered ring acts as a dual ideal site for efficient Ag⁺ adsorption and rapid charge transfer due to its short bond length and high electron localization. This work provides atomic-level insights for optimizing nitrogen-doped carbon-based CDI materials.