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Capacitive Deionization (CDI), a burgeoning desalination technology, effectively removes ionic species from aqueous solutions. One-dimensional (1D) electrospinning nanomaterial electrodes present unique opportunities for the enhancement of CDI performance, resulting in increased salt removal capacities and energy-efficient desalination for high-salinity streams. The review begins by elaborating on electrospinning principles, along with parameter considerations influencing said technology. We discuss post-electrospinning treatments such as carbonization, hydrothermal methods, and surface modifications, explicating their resultant impact on the structural, compositional, and morphological attributes of the nanocomposite fabrics synthesized through electrospinning. Progressing further, the analysis categorizes CDI cell architectures and introduces performance assessment metrics for CDI. Moreover, it presents an exploration of the multifarious applications of electrospinning nanomaterials in diverse industrial sectors. These applications incorporate the removal of heavy metals, resource recovery, and water disinfection processes. The potential benefits in these areas appear promising, signifying the requirement for further research toward optimizing the design of electrospinning nanomaterial electrodes to suit these specific purposes more effectively. Lastly, we delineate the existing challenges and potential research avenues, aiming to provide strategic guidance for future inquiries. The evolution of electrospinning nanomaterial electrode technologies could shed light on the emerging CDI research frontier and engender further environmental exploration. [Display omitted] • This paper reviews the growths in 1D electrospinning nanomaterials for CDI. • The post-electrospinning treatments of advanced electrode are discussed in depth. • The versatile applications of capacitive deionization are discussed extensively. • It provides a new perspective for the progress of 1D electrospinning electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • This paper reviews the growths in freestanding pseudocapacitive electrode for CDI. • The preparation methods of advanced freestanding electrode are discussed in depth. • The research progress of electrode materials in different dimensions is elaborated. • The versatile applications of capacitive deionization are discussed extensively. • Provides a new perspective for the progress of freestanding electrode in the future. The development of advanced freestanding pseudocapacitive electrode materials with controlled topography, structural complexity, and improved desalination performance has garnered significant interest in recent years, particularly as water scarcity becomes increasingly prevalent. In this paper, we present a comprehensive review of recent advancements in the rational design of freestanding electrodes for hybrid capacitive deionization (CDI) to enhance their desalination capacity, stability, and selectivity. The review begins by summarizing advanced electrode materials that have been fabricated using different methods to boost CDI performance. Various novel synthetic strategies are discussed, highlighting their effectiveness in improving electrode capacitance, increasing active site density, and optimizing pore structure. The focus then shifts to categorizing electrode materials into low-dimensional and 3D hierarchical porous structures to boost their electrochemical and CDI properties. Furthermore, the review discusses the applicability of CDI in versatile industrial processes, including heavy metal removal, resource recovery, water softening, and water disinfection. The potential of CDI in these applications is promising, and further research is needed to optimize the design of freestanding electrodes for these specific purposes. Finally, the review concludes with a summary and outlook, providing comments on current scientific and technical challenges and future developments. With the advancement of advanced freestanding electrode materials, it is anticipated that this review will shed light on the emerging field of hybrid CDI in environmental research and stimulate further research in this area. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible free-standing hierarchical SnS 2 @NC hybrid electrode was fabricated. • The hollow structure alleviates volume expansion and facilitates ion diffusion. • A high electrosorption capacity and a rapid salt adsorption rate were achieved. • Work function-driven interfacial electron transfer accelerates reaction kinetics. Constructing pseudocapacitive electrodes with high specific capacities is indispensable for increasing the large-scale application of capacitive deionization (CDI). However, the insufficient CDI rate and cycling performance of pseudocapacitive-based electrodes have led to a decline in their use due to the corresponding volumetric expansion and contraction that occurs during long-term CDI processes. Herein, hierarchical porous SnS 2 nanoflakes are encapsulated inside an N -doped carbon (NC) matrix to achieve efficient CDI. Benefiting from the synergistic properties of the pseudocapacitive SnS 2 nanoflakes and few-layered N -doped carbon, the heterogeneous interface simultaneously provides more available vigorous sites and demonstrates rapid charge-transfer kinetics, resulting in a superior desalination capability (49.86 mg g−1 at 1.2 V), rapid desalination rate (1.66 mg g−1 min−1) and better cyclic stability. Computational research reveals a work function-induced surface charge redistribution of the SnS 2 @NC heterojunction, which can lead to an auspicious surface electronic structure that reduces the adsorption energy to improve the diffusion kinetics toward sodium adsorption. This work contributes to providing a thoughtful understanding of the interface engineering between transition metal dichalcogenides and NC to construct high-performance CDI electrode materials for further industrialization. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) technology, renowned for its operational simplicity, energetic efficiency, and cost-effectiveness, has gained prominence as a powerful solution for water desalination and decontamination. With time, the predominance of CDI has evolved from mere saline reduction in brackish water to targeted removal of hazardous impurities. In particular, fluoride, an ion with substantial health repercussions, has been identified as a key eradication target. In this context, the advent of potent and cost-friendly methods for eradicating fluoride from water becomes crucial-a requisite that CDI technology is promisingly equipped to fulfill. Herein, this article presents a comprehensive review of recent advancements in the design and synthesis of nuanced materials characterized by tailored morphology, structural complexity, and enhanced fluoride elimination performance. As a departure from previous reviews, this piece commences by delineating the merits and limitations of conventional fluoride purging methods. Thereafter, the discussion is steered toward the burgeoning field of advanced pseudocapacitive electrode materials for fluoride expulsion, crafted using a variety of organic and inorganic active substances. These range from carbon material, hydroxyapatite, layered metal oxide, and to metal-organic frameworks (and their derivatives) as well as conducting polymers. The inherent morphological and structural attributes of these materials significantly dictate their ultimate efficacy in fluoride removal. The review also delves into some of the prevailing scientific challenges and opportunities linked to fluoride purging applications. With the intent of grabbing the attention of scholars worldwide for the design and synthesis of high-utility materials for fluoride extraction, this article aims to pave the way for future explorations in this critical research area. [Display omitted] • The paper reviews the growths in CDI electrode toward fluoride elimination. • Merits and shortcomings of conventional methods for fluoride elimination. • Fundamentals understanding of CDI technology is elaborated. • Challenges and future outlook for fluoride elimination applications are discussed. [ABSTRACT FROM AUTHOR]

As water scarcity intensifies, the quest for developing sophisticated electrode materials with adjustable configurations, complex structures, and developed desalination performance garners important interest. Prussian Blue (PB) and its analogs (PBAs), owing to their cost-effectiveness, uncomplicated synthesis, innate open framework, and modifiable composition, have elicited considerable recognition. Herein, the paper provides a comprehensive overview and analysis of the advances made in capacitive deionization electrodes based on PB and PBAs. It commences by detailing the synthesis techniques, post-treatment processes, and derivatives of standard PBs and PBAs. Subsequent sections propose strategies to minimize auxiliary reactions in electrochemical processes, encompassing structural design, protective coatings, substitution, and the confinement effect. Subsequently, emphasis is placed on structures that have potential as electrode materials in applications such as desalination, heavy metal removal, resource recovery, and water softening. A summary of current achievements in the field is provided, alongside a critique of prevailing limitations and emergent challenges. As advancements in electrode materials continue to unfold, it aims to stimulate innovative ideas for utilizing PB and PBAs in environmental research, thereby catalyzing additional investigation into the desalination area. [Display omitted] • The preparation methods of advanced PB/PBAs electrode are discussed in depth. • The versatile applications of PB/PBAs electrode are discussed extensively. • The future orientation development of PB/PBAs in CDI is provided. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible hierarchical NiCo 2 O 4 @CNFs membrane electrode was fabricated for CDI. • The hollow structure alleviates volume expansion and facilitates ion diffusion. • A high electrosorption capacity and a rapid salt adsorption rate were achieved. Crafting an ideal capacitive deionization (CDI) cathode presents a significant challenge, owing to the myriad requisites it must fulfill. These entail a high specific capacitance, commendable conductivity, stability, and the counteraction of the shortcomings inherent in additive/binder electrodes. Realizing all these attributes from a single-component material, however, is a daunting task. In this investigation, we present our findings on the in-situ cultivation of ultrathin NiCo 2 O 4 nanoneedle arrays on freestanding electrospinning nitrogen-enriched carbon nanofibers devised to tackle these hurdles. The resultant material boasts remarkable features that not only alleviate tension triggered by phase transition but also accentuate electric conductivity. Electrochemical evaluations authenticate the effectiveness of structural modulation, reflected through a markedly augmented specific capacitance, superior stability, and diminished electrochemical resistance. Furthermore, the assembled pliable, asymmetric CDI cell incorporating electrospinning carbon nanofiber showcases superior desalination capabilities (38.86 mg g−1 at 1.2 V), a swift desalination rate (0.65 mg g−1 min−1), and improved cycle stability. This work finding contribute valuable interpretations towards proficiently designing and developing advanced CDI electrode materials capable of meeting the stringent requisites for high specific capacitance, good conductivity, and stability. It further propels progress towards industrialization, thereby expediting the realization of practical applications. [ABSTRACT FROM AUTHOR]

Abundant endeavors have been undertaken to explore high-quality and inexpensive materials for capacitive deionization desalination. However, one major problem is the sluggish adsorption rate and inferior adsorption performance of these materials in practical applications. Herein, nitrogen-doped carbon nanofiber-reinforced hierarchical hollow iron oxide nanorods grown on electrospinning carbon nanofibers (denoted Fe 2 O 3 @CNFs) were rationally designed and synthesized for high-efficiency capacitive deionization. Such composition and distinctive hierarchical porous structure prevent agglomeration of Fe 2 O 3 nanorods, boosting the ionic/electronic transport through the synergistic effect between the Fe 2 O 3 nanorods and N-doped carbon nanofibers. When employed as a cathode for capacitive deionization without adding any polymeric binder or conductive additives, this material exhibits a high adsorption capacity of 114.97 mg/g and a rapid salt adsorption rate (7.79 mg/g min). Moreover, the sodium storage mechanism was revealed through ex situ XRD, EDX mapping and ex situ XPS. Density functional theory (DFT) calculations reveal that the electrons are redistributed at the heterojunction interface, refining the electrochemical activity. This work is anticipated to afford an innovative path for the development of porous transition metal oxide-based fibers with outstanding effectiveness and stability toward environmental research of high-performance capacitive deionization. [Display omitted] • A free-standing hierarchical hollow Fe 2 O 3 @CNFs hybrid electrode was fabricated. • A high electrosorption capacity and a rapid salt adsorption rate were achieved. • The hollow structure alleviates volume expansion and facilitates ion diffusion. • The faradic reaction and electroadsorption coupling removal mechanism was proven. • DFT were implemented to provide in-depth insights into the storage mechanism. [ABSTRACT FROM AUTHOR]