Nitrogen-doped nanostructured carbons: A new material horizon for water desalination by capacitive deionization

Capacitive deionization (CDI) is regarded as a novel, low-cost, and environmentally friendly technique that plays a critical role in desalination and water treatment. Although much progress has been achieved, the development of better CDI technologies, especially through the design and synthesis of various porous carbonaceous materials with enhanced CDI performance, continues to attract increasing interest within the scientific fraternity. Considering that previous traditional porous carbons might suffer from deficient salt adsorption capacity, the nitrogenization of porous carbons, which brings new opportunities for CDI applications, has emerged as an effective strategy to modify the surface characteristics of porous carbons and ultimately improve their CDI performance. This review summarizes the recent significant breakthroughs on the construction of NCs, including in situ doping and post-treatment strategies, and their practices in the field of CDI to impart a comprehensive understanding of the strategic evolution of the synthetic approaches to nitrogen-doped carbons (NCs) with remarkable CDI characteristics. We present an exhaustive analysis of newly synthesized NCs and the impact of their compositional and structural features on their CDI performance; further, we highlight a special emphasis on the possible role of nitrogen dopants in the CDI process. In addition to elucidating the state-of-the-art CDI applications, we address the remaining challenges, and finally, the possible direction for the use of NCs for CDI is described to provide some useful clues for future developments in this promising field.