Construction of 2D-2D heterojunctions of VN nanosheets within Ti3C2 nanosheets for improved flow-electrode capacitive deionization performance

A study of the effect of carbon characteristics on capacitive deionization (CDI) performance

Can capacitive deionization outperform reverse osmosis for brackish water desalination?

MXenes, as a novel two-dimensional lamellar material, has attracted much attention. However, MXenes lamellar are prone to collapse and stacking under hydrogen bonding and interlayer van der Waals forces, which affects their electrochemical and capacitive deionization performance. A three-dimensional Ni-1,3,5-benzenetricarboxylate/Ti3C2Tx (Ni-BTC/Ti3C2Tx) composite electrode material was developed to enhance the electrochemical and capacitive deionization performance. The uniformly decorated Ni-BTC can prevent MXenes from aggregation and provide a large specific surface area and rich pore structure. As a substrate supporting Ni-BTC, MXenes can effectively disperse the growth of Ni-BTC and enhance the ion transport rate. In addition, the unique three-dimensional structure of Ni-BTC/Ti3C2Tx provides horizontal charge transfer paths like two-dimensional nanosheets and has unique vertical charge transfer paths between nanosheets. Therefore, the Ni-BTC/Ti3C2Tx exhibits an exceptional chromium(VI) removal rate of 94.1%. The electrosorption capacity of the Ni-BTC/Ti3C2Tx for chromium(VI) is 124.5 mg g−1, much higher than that of the pure Ti3C2Tx (55.5 mg g−1). The superior CDI efficiency accomplished through the Ni-BTC/Ti3C2Tx electrode is due to the unique three-dimensional network structure and synergistic effect of the pseudocapacitance generated by the unique assembly of Ni-BTC and Ti3C2Tx. Ni-BTC/Ti3C2Tx is a promising CDI electrode material that can be used for capacitive deionization.

Optimized desalination performance of high voltage flow-electrode capacitive deionization by adding carbon black in flow-electrode

Improving capacitive deionization performance by using O2 plasma modified carbon black

Nitrogen-doped porous carbons with high surface area for capacitive deionization

Anion-/cationic compounds enhance the dispersion of flow electrodes to obtain high capacitive deionization performance

Analysis of the desalting performance of flow-electrode capacitive deionization under short-circuited closed cycle operation

Capacitive deionization (CDI) using a flow-electrode primarily composed of porous materials and an aqueous electrolyte, exhibits continuous deionization and a high desalting efficiency. The development of flow-electrodes with high capacitance and low resistance is essential for achieving an efficient flow-electrode capacitive deionization (FCDI) system with low energy consumption. For this purpose, studies on conductive additives (CAs) that do not clog the flow-channel must be conducted. Here, we evaluated the desalting performance of flow-electrodes with spherical and plate-type conductive additives having sizes between 1 and 10 μm and possessing powder conductivities similar to or higher than nano-sized carbon black, which is often used as the CA in solid fixed electrodes in conventional CDI systems. We confirmed that plate-shaped CAs reduced resistance near the pores and enhanced the desalting performance of the flow-electrodes in FCDI systems. The positive effect of such plate-shaped CAs appears to originate from efficient charge percolation between the ACs via the electrical conductive direction of the graphite and the alignment of the exposed graphite edges to the pumping direction of the flow-electrode. Finally, we verified that the flow-electrode with the newly discovered micro-sized CA could be operated without clogging the flow-channel in FCDI and showed an improved desalting performance of around 1.5 times compared the flow-electrode without the micro-sized CA for extended periods of time.

Nitrogenization of porous carbon provides an effective methodology to promote capacitive deionization (CDI) performance. Exploring a new class of nitrogen-doped porous carbons from waste biomass over commercially available activated carbons is of significant interest in CDI. In this contribution, we present the preparation of nitrogen-doped porous carbon microtubes (N-CMTs) by pyrolyzing willow catkins, a naturally abundant biomass with urea as the nitrogen source. Due to the naturally occurring hollow microtube structure and the high nitrogen content, the as-prepared N-CMTs show an enhanced desalination performance compared to undoped samples. A high deionization capacity of 16.78 mg g−1 predicted by Langmuir isotherm and a stable cycling performance over ten cycles are observed. The result advocates the importance and significance of naturally developed architectures and chemistry for practical CDI application.

Enhancing capacitive deionization performance with charged structural polysaccharide electrode binders

Design and optimization of electrode materials plays the pivotal role on the performance of capacitive deionization (CDI). Activated carbon (AC) has been a workhorse material for electrode fabrication in capacitive technologies. Several modification methods have been reported with enhanced activity and versatility attributes. Undeniably, tuning and tailoring AC properties have opened avenues for broadening the scope of applications, by meeting necessary features of electrodes for a given CDI cell configuration. This review traces the beneficial and also detrimental effects from various modifiers on AC electrodes with respect to CDI performance. Furthermore, a comprehensive classification of CDI cells based on different architectural aspects with a comparative performance is presented. On this basis, the tradeoff between physical, chemical, electrochemical properties in the course of electrode modification and the interdependence between electrode design and CDI cell configuration are discussed with disclosing some prospective guidelines on AC electrode design. It is important to evaluate the electrode materials and modifications in the way of practical including not only the electrode design, but also the cell architecture and operational parameters. This review aims to raise the attention on the rational electrode design by taking into account all necessary features of electrode in a given cell configuration.

A novel liquid binder, which is called AA in this paper, was synthesized with acrylic acid and azodiisobutyronitrile to prepare electrodes from activated carbon (AC, ACE) for capacitive deionization (CDI). The ACE prepared with AA (ACE-AA) was carbonized to improve its CDI performance. As a result, its wettability was significantly improved, and the specific capacitance was increased by a factor of 8. The optimization showed that electrodes with a mass fraction of AC of 35 wt% had the best CDI performance. Compared with ACEs prepared with phenolic resin (PR), polytetrafluoroethylene (PTFE) and epoxy resin (ER), electrodes prepared using AA binder showed improved flexibility, durability, wettability, and desalination ratio. Therefore, the ACE-AA seems to be a very promising carbon electrode for CDI.

Equivalent film-electrode model for flow-electrode capacitive deionization: Experimental validation and performance analysis

The polymeric conformational effect on capacitive deionization performance of graphene oxide/polypyrrole composite electrode