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

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 NaTi2(PO4)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.