Porous NaTi₂(PO₄)₃ Nanoparticles Encapsulated in Nitrogen-Doped Carbon Matrix for High-Performance Capacitive Deionization

Abstract

Capacitive deionization (CDI) is an emerging and promising technique for the deionization of brackish water due to its low energy consumption, low cost, and high environmental safety. However, its low desalination capacity limits its commercial applications. Herein, a unique nanostructure consisting of NaTi 2 (PO 4 ) 3 (NTP) nanoparticles uniformly encapsulated in a nitrogen-doped carbon matrix was prepared by a sol−gel method.The carbon matrix provides a highly conductive layer for NTP and ensures the highly efficient insertion/extraction of cations. The charge-storage mechanism dominated by pseudocapacitance allows the NTP-0.5/C−N composite to achieve a large salt adsorption capacity (31.22 mg g −1 ) and an ultrafast salt adsorption rate (6.08 mg g −1 min −1 ) in a 500 mg L −1 NaCl solution at 1.4 V. Remarkably, it also shows an excellent salt adsorption performance of 98.74 mg g −1 in a 3000 mg L −1 NaCl solution in a membrane capacitive deionization system.

Spinel Nickel Ferrite on Metal–Organic Framework-Derived Porous Carbon as a Robust Faradaic Electrode for Enhanced Flow Capacitive Deionization

“…The SAC of NiFe 2 O 4 @PC-500 was increased from 6.7 to 19.7 mg/g within a potential range of 0.4–1.2 V. With an increase in the applied potential from 0.4 to 1.4 V, the average salt removal rate (ASRR) was increased from 0.84 to 3.34 μmol cm –2 min –1 . Typically, at higher potentials, the level of migration of oppositely charged ions toward the electrode increases by creating a large electrostatic force, leading to an improved ion adsorption efficiency. , However, a steep decline in desalination performance was observed with an applied potential of >1.2 V, inferring the development of several complex parasitic reactions of water electrolysis, oxygen reduction, and oxidation of carbon . It was noted that with a potential of >1.2 V, energy consumption was enhanced continuously.…”

“…Typically, at higher potentials, the level of migration of oppositely charged ions toward the electrode increases by creating a large electrostatic force, leading to an improved ion adsorption efficiency. 37,38 However, a steep decline in desalination performance was observed with an applied potential of >1.2 V, inferring the development of several complex parasitic reactions of water electrolysis, oxygen reduction, and oxidation of carbon. 39 It was noted that with a potential of >1.2 V, energy consumption was enhanced continuously.…”

Prussian Blue/Carbon Nanofiber Amalgamated Conductive Scaffolds for Capacitive Deionization

“…Therefore, the various cathode materials (intercalated electrode materials) for sodium-ion batteries have been explored as CDI electrodes. Different from the EDL capacitance mechanism of carbon materials, the mechanism of intercalation materials is to store cations through the insertion/deinsertion of ions in the lattice, so the cathode materials of sodium-ion batteries have received more attention than carbon materials. − Intercalation materials include sodium manganese oxide (NMO), , manganese dioxide (MnO 2 ), − sodium superionic conductors (NASICON), − Prussian blue analogues (PBAs), − transition-metal dichalcogenide (TMDC), , and MXene. − For most of the above intercalation materials, the synthesis requires multistep and special conditions, which limits commercial applications. Meanwhile, PB nanoparticles are one of the most excellent candidates due to their spacious three-dimensional ion diffusion channels, easily scalable synthesis method, and available low-cost raw materials …”