A review on capacitive deionization: Recent advances in Prussian blue analogues and carbon materials based electrodes

Capacitive Deionization (CDI) is a promising technology with great potential for water purification and desalination, particularly in areas facing energy and water scarcity issues. CDI operates at extremely low voltages ranging from 1 to 1.6 V, making it an energy-efficient technology that can be powered by portable sources such as batteries and supercapacitors. Additionally, CDI is a cost-effective and scalable solution that generates less waste. This review provides a comprehensive overview of recent advances in CDI. The review focuses on theoretical modeling, an important aspect of CDI that helps elucidate the underlying principles and mechanisms affecting the CDI process. Mathematical models based on electrochemistry, fluid dynamics, and ion transport principles have been developed to simulate the processes within the CDI system. These models facilitate a deeper understanding of phenomena such as ion adsorption, electric potential distribution, and fluid flow patterns. Furthermore, the review discusses the potential of Prussian blue analogues (PBAs) as emerging materials for CDI applications, including synthesis methods and structural properties. CDI electrodes made of carbon materials such as activated carbon, carbon aerogel, and carbon nanotubes are compared with PBAs. Finally, the review addresses the challenges and future perspectives of utilizing carbon materials and PBAs in CDI.