Faradaic and Nonfaradaic Electrode Innovations on Brackish Water Reduction by Capacitive Deionization: A Critical Review

Capacitive Deionization (CDI) has become a viable and energy-efficient desalination process nowadays. Conventional electrodes for CDI application possessed low ion adsorption capability. Recent advancements focus on faradaic electrodes, which exploit redox reactions to produce improved ion storage through pseudocapacitive and intercalation effects. Advanced materials offer improved desalination efficiency, operating adaptability, and charge storage properties. Advanced CDI electrode efficiency improved due to faradaic ion storage, such as cathodic oxygen reduction and intercalation reactions which resulted through the development of electrode functionality and design. This review thoroughly examines recent developments in capacitive and faradaic materials-based electrodes for CDI, focusing on material synthesis and performance optimization. The review outlines limitations such as parameter optimization, electrode deterioration, and integration into scalable CDI systems. Emerging materials offer effective desalination efficacy by tackling these limitations. This review critically analyzes the drawbacks of traditional carbon-based CDI electrodes and their physiochemical advancements, and assesses their economic viability.