Fabrication of polyvinylidene fluoride-derived porous carbon heterostructure with inserted carbon nanotube via phase-inversion coupled with annealing for capacitive deionization application.

As a promising desalination technology, capacitive deionization (CDI) has great potential to guarantee freshwater supply. It is urgently needed to explore novel electrode materials with excellent desalination performance. Herein, the PVDF-derived porous carbon heterostructure with inserted carbon nanotube (PPC/CNT) was prepared via phase-inversion coupled with annealing strategy and applied as electrode material for CDI desalination. The resultant PPC/CNT possesses the combined structural advantages of PPC and CNT, such as high specific surface, mesoporous structure and improved conductivity. By virtue of these remarkable properties, PPC/CNT exhibites an excellent electrosorption capacity of 15.1 mg/g in 500 mg/L NaCl, while that of PPC electrode is 10.3 mg/g. Specially, the charge efficiency of PPC/CNT electrode is 1.39 times higher as compared to PPC, which is largely responsible for the improvement of electrosorption capacity. Besides, PPC/CNT electrode demonstrated good cycle stability over 10 electrosorption-desorption cycles. Thus, PPC/CNT electrode presents promising prospects as CDI electrode for water desalination. This work may shed new light on the rational design of porous carbon heterostructures with suitable host matrix and improved conductivity, subsequently developing the CDI performance.