Coordination Confined Silver-Organic Framework for High Performance Electrochemical Deionization

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Engineering

Background:

• Silver (Ag) is a promising anode material for capacitive deionization (CDI) due to its high theoretical capacity and selectivity for chloride ions (Cl^-).
• Conventional Ag electrodes suffer from poor cycling performance due to volume changes during conversion reactions and Ag agglomeration.
• Developing stable and highly dispersed Ag-based electrodes is crucial for efficient CDI.

Purpose of the Study:

• To develop a novel Ag-based metal-organic framework (Ag-MOF) for CDI anodes.
• To overcome the limitations of conventional Ag electrodes, such as poor cycling stability and agglomeration.
• To enhance the utilization of active sites and interfacial stability of Ag in CDI.

Main Methods:

• Construction of Ag-MOF using organic linker confinement strategy and MOF chemistry.
• Electrochemical performance evaluation for Cl^- removal in CDI.
• Characterization using density functional theory (DFT) calculations, ex situ XRD, ex situ Raman, and XPS to elucidate the capture mechanism.

Main Results:

• Ag-MOF demonstrated a high Cl^- removal capacity of 121.52 mg g^-1 at 20 mA g^-1 in 500 mg L^-1 NaCl solution.
• Achieved a high Ag utilization rate of 60.54% and excellent capacity retention of 96.93% after 100 cycles.
• Uniform dispersion of Ag at the molecular level within the MOF structure enhanced active site utilization and interfacial stability.

Conclusions:

• The organic linker confinement strategy in Ag-MOF effectively addresses the limitations of conventional Ag electrodes for CDI.
• Ag-MOF presents a high-performance conversion electrode for efficient and stable Cl^- removal in capacitive deionization.
• This electrode design provides valuable insights for developing advanced materials for water purification.