Carbon electrodes for capacitive deionization

Huang, Zheng‐Hong; Yang, Zhiyu; Kang, Feiyu; Inagaki, Michio

doi:10.1039/c6ta06733f

Cited by 311 publications

(156 citation statements)

References 166 publications

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“…Our results show that capacitive performance in CDI cells with all pristine carbon electrodes and air‐saturated solution is mainly constrained by reactions (1) and (2) at any realistic operating potential. Moreover, even if materials were developed with high overpotentials towards these reactions in order to widen the non‐faradaic performance window, a cell may not necessarily operate 100 % efficiently; surface chemistry, electrode E PZC ’s, co‐ion repulsion, and pseudocapacitance also play key roles in the net absorption of salt …”

Section: Resultsmentioning

confidence: 61%

Quasi‐Steady‐State Polarization Reveals the Interplay of Capacitive and Faradaic Processes in Capacitive Deionization

et al. 2017

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We employ slow cyclic voltammetry to study the quasi‐steady‐state capacitive deionization (CDI) of aerated 10 mM NaCl from Vcell=−0.2 to 2 V. The method allows for the deconvolution of capacitive and faradaic processes, which are significant even at low voltage, in conjunction with pH, conductivity, dissolved oxygen (DO), and electrode potential measurements. The pH at three locations and effluent DO data identify asymmetric electrosorption in the cell configured with pristine activated carbon electrodes, where charge is irreversibly consumed to produce H+/OH− instead of reversibly adsorbing Cl−/Na+. Implementing a reference electrode resolves ion adsorption as a function of the individual potential at each electrode. Near‐electrode pH probes reveal pH environments that diverge by up to 8 units during cell polarization and allow more accurate calculation of faradaic redox potentials in a flow‐by CDI cell. In the aerated NaCl solution that will be relevant to industrial‐scale water treatment, we find that DO reduction occurs to a greater degree than Na+ adsorption at the cathode until DO removal becomes mass transfer limited at <−0.2 V vs. SHE. Two cell architectures – flow‐by and flow‐through – corroborate our findings. Finally, we reconcile all measurements to generate a map displaying how the potential is partitioned amongst the capacitive and faradaic processes occurring during CDI operation over a 2.2 V window.

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Section: Resultsmentioning

confidence: 61%

Quasi‐Steady‐State Polarization Reveals the Interplay of Capacitive and Faradaic Processes in Capacitive Deionization

et al. 2017

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“…A myriad of studies aimed at enhancing these properties has culminated in three broad categories of materials: traditional carbon, advanced carbon, and pseudocapacitive. Traditional carbon materials encompass activated carbon, activated carbon cloth, carbon aerogel, and mesoporous carbon electrodes, 13,[88][89][90][91] whereas we classify advanced carbon electrodes as those which incorporate graphene, carbon nanotubes, or other carbon-based nanomaterials. [92][93][94] Pseudocapacitive electrode materials are defined by their use of ion intercalation as a method for ion removal-either as the sole mechanism or in conjunction with EDL-based ion capture.…”

Section: Electro-driven Desalination: Capacitive Deionizationmentioning

confidence: 99%

The relative insignificance of advanced materials in enhancing the energy efficiency of desalination technologies

Patel

Ritt

Deshmukh

et al. 2020

Energy Environ. Sci.

221

151

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“…Most work on CDI uses electrodes with ion storage in materials based on carbon (activated carbon, carbon nanotubes, graphene, etc.) where ions are stored in the electrical double layer (EDLs) along the carbon surface [4].…”

Section: Introductionmentioning

confidence: 99%

Theory of Water Desalination with Intercalation Materials

et al. 2018

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We present porous electrode theory for capacitive deionization (CDI) with electrodes containing nanoparticles that consist of a redox-active intercalation material. A geometry of a desalination cell is considered which consists of two porous electrodes, two flow channels and an anion-exchange membrane, and we use Nernst-Planck theory to describe ion transport in the aqueous phase in all these layers. A single-salt solution is considered, with unequal diffusion coefficients for anions and cations. Similar to previous models for CDI and electrodialysis, we solve the dynamic two-dimensional equations by assuming that flow of water, and thus the advection of ions, is zero in the electrode, and in the flow channel only occurs in the direction along the electrode and membrane. In all layers, diffusion and migration are only considered in the direction perpendicular to the flow of water. Electronic as well as ionic transport limitations within the nanoparticles are neglected, and instead the Frumkin isotherm (or regular solution model) is used to describe local chemical equilibrium of cations between the nanoparticles and the adjacent electrolyte, as a function of the electrode potential. Our model describes the dynamics of key parameters of the CDI process with intercalation electrodes, such as effluent salt concentration, the distribution of intercalated ions, cell voltage, and energy consumption.

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Carbon electrodes for capacitive deionization

Abstract: Carbon materials for electrodes of capacitive deionization (CDI) process are reviewed.

Cited by 311 publications

References 166 publications

Quasi‐Steady‐State Polarization Reveals the Interplay of Capacitive and Faradaic Processes in Capacitive Deionization

Quasi‐Steady‐State Polarization Reveals the Interplay of Capacitive and Faradaic Processes in Capacitive Deionization

The relative insignificance of advanced materials in enhancing the energy efficiency of desalination technologies

Theory of Water Desalination with Intercalation Materials

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