A Review on Recent Progress in Metal-Organic Frameworks for Capacitive Deionization

The escalating challenge of supplying freshwater stems from an alarming rise in water consumption driven by population growth and increased economic activity. With worsening freshwater scarcity, water pollution, and 80% of wastewater worldwide containing high TDS, heavy metals, and inorganic and organic contaminants, the need to obtain freshwater from nonfreshwater sources is essential. Capacitive deionization (CDI) is an emerging, promising electrochemical technique that offers robustness, cost-effectiveness, and high efficiency. CDI is a cost- and energy-efficient alternative for applications such as desalination and the elimination of heavy or radioactive metals. This review discusses the general concepts of CDI, including different cell designs, adsorption and desorption cycles, and evaluation parameters, to provide a foundation. Later, we describe the potential of metal-organic frameworks (MOFs) as electrode materials for CDI, the recently reported modifications and developments in MOF-based electrode materials, their CDI performance, and the underlying mechanisms for desalination and ion capture. This review concludes with future perspectives for further developments in the field of capacitive deionization.