Desalination is a sustainable process that removes sodium and chloride ions from seawater. Herein, we demonstrate a faradaic mechanism to promote the capacity of capacitive deionization in highly concentrated salt water via an electrochemical deionization device. In this system, ion removal is achieved by the faradaic mechanism via a constant current operation mode, which is improved based on the constant voltage operation mode used in the conventional CDI operation. Benefiting from the high capacity and excellent rate performance of Prussian blue as an active electrochemical reaction material, the designed unit has revealed a superior removal capacity with an ultrafast ion removal rate. A high removal capacity of 101.7 mg g has been obtained with proper flow rate and current density. To further improve the performance of the EDI, a reduced graphene oxide with nanopores and Prussian blue composite has been synthesized. The PB@NPG has demonstrated a high salt removal capacity of 120.0 mg g at 1 C with an energy consumption of 6.76 kT per ion removed, which is much lower than most CDI methods. A particularly high rate performance of 0.5430 mg g s has been achieved at 40 C. The faradaic mechanism promoted EDI has provided a new insight into the design and selection of host materials for highly concentrated salt water desalination.

Recent research on materials for capacitive deionization (CDI) has shown that intercalation materials have salt removal capacities (>40 mg g −1 ) much higher than those of carbon materials (∼15 mg g −1 ). However, little work has been done to elucidate the relationship between the microstructure of an intercalation material and its desalination performance. Herein, we report the desalination performances of various crystalline forms of MnO 2 in a hybrid CDI setup without the use of ion-exchange membranes. MnO 2 materials used in our experiments were either poorly crystalline or crystalline forms of 1D hollandite α-MnO 2 , 2D birnessite δ-MnO 2 , and 3D spinel λ-MnO 2 . X-ray photoelectron spectroscopy performed on electrochemically cycled MnO 2 showed redox changes associated with intercalation processes in crystalline MnO 2 , whereas poorly crystalline MnO 2 showed no such changes. It was further shown that surface adsorption is dominant in poorly crystalline MnO 2 and that poorly crystalline forms of α-MnO 2 and δ-MnO 2 exhibited the highest salt removal capacities of 0.17 and 0.16 mmol g −1 (9.93 and 9.35 mg g −1 ), respectively. These performances are comparable to state-of-the-art carbon materials and are remarkable considering the low surface areas (<400 m 2 g −1 ) of MnO 2 materials.

Aqueous zinc ion batteries (AZIBs) have recently sparked an enormous surge of research attentions, due to their eco-friendliness, low-production cost, and exceptional electrochemical performance. Nonetheless, initial exploration mainly focused on...

No abstract

Porous carbons derived from bimetallic metal–organic frameworks exhibit tunable properties by controlling the ratio of metal ions (Zn and Co) in the precursors. With the optimal ratio of Zn/Co = 3 in the precursors, the porous carbons possess a superior electrosorption capacity of 45.6 mg g−1.