Significant stability enhancement of Ag@carbon electrode based on physical confinement of carbon nanocage and its application in capacitive deionization

Selective dechlorination is the key to solving the pollution problem of saline wastewater and achieving resource recovery, which is a major challenge for existing treatment methods. The recent development of capacitive deionization (CDI) based on the Ag@carbon electrode exhibits highly selective Cl- removal; however, its industrialization still poses a significant challenge due to the agglomeration and subsequent falling of Ag nanoparticles in the electrochemical field. In this work, we proposed a new physical confinement strategy based on carbon nanocage that can suppress the migration and agglomeration behavior of Ag nanoparticles. Firstly, a controllable construction of porous carbon nanocages on the surface of Ag nanoparticles was realized by the Ag+/H2O2 synergistic oxidation -carbonization process, significantly inhibiting the migration and agglomeration of Ag nanoparticles in the Ag@carbon electrode. The Cl- removal capacity fluctuated around 110.0 mg & sdot;g- 1 in 100 CDI cycles, exhibiting an excellent stability. Meanwhile, the high Cl-/SO42- selectivity coefficient (89.0) promised the efficiently selective separation of Cl- ions from saline wastewater. In particular, the migration and agglomeration of Ag species in the carbon matrix was mainly attributed to the mutual attraction-recrystallization of Ag nanoparticles in the electrochemical field. Consequently, our study provides significant support for the industrial application of Ag@carbon electrodes and fundamentally solves the problem of saline wastewater pollution.